Thursday, December 27, 2012

Endovascular Management of TIPS-related Hepatic Encephalopathy

Hepatic encephalopathy is a common complication that occurs after creation of a TIPS shunt. It is typically managed conservatively with modifications in diet and medication. In patients who do not respond to conservative management, liver transplantation may be an option. Some endovascular techniques aimed at reducing the amount of blood shunted away from the liver may also be employed.
  • shunt occlusion via embolic agents
    • has risk of variceal rebleeding
    • sudden changes in hemodynamics (cardiac output, hypotension, metabolic acidosis) can be fatal
    • reversible shunt occlusion using short term balloon occlusion of the TIPS can prevent complications from variceal rebleeding (occlusive balloon can be deflated if life threatening bleeding occurs and thus TIPS can be reopened)
  • shunt reduction
    • using constrained stents to reduce the lumen of the shunt
    • makes it difficult to regulate blood flow through the shunt, especially around the constrained portions
      • adjunct embolization of the dead space around the shunt can be performed
      • use of constrained covered stent grafts has allowed better control of flow through the shunt while reducing its lumen
  • retrograde embolization of a splenorenal shunt with ethanolamine oleate
    • can only be done when a spontaneous splenorenal shunt is present
    • maintains patency of TIPS
    • severe renal dysfunction and pulmonary edema are among some of the side effects of ethanolamine usage
REFERENCES
Madoff DC, Wallace MJ, Ahrar K, et al. TIPS-related hepatic encephalopathy: management options with novel endovascular techniques. Radiographics 2004;24:21-36.

Wednesday, December 26, 2012

Hibernomas


  • rare, benign tumor composed of brown (immature) fat
  • slow growing, painless soft tissue mass
  • 4 subtypes: typical, myxoid, lipoma-like, spindle cell
  • 3rd-4th decade of life
  • slight female predominance
  • US: well circumscribed, hyperechoic, hypervascular
  • CT: intermuscular mass with density between that of fat and muscle
  • MR: appearance varies based on subtype; branching vessels are often seen; T1WI - usually hyperintense to muscle but hypointense to subcutaneous fat, prominent septa; T2WI - variable
  • NM: moderate uptake on blood pool images in bone scintigraphy
  • PET: increased FDG uptake 
  • Angiography: hypervascular, intense blush, arteriovenous shunting; do not do a core biopsy
  • treatment: surgical resection

REFERENCES
Murphey MD, Carroll JF, Flemming DF, et al. Benign musculoskeletal lipomatous lesions. Radiographics 2004;24:1433-66.

Monday, December 24, 2012

Pyelonephritis Mimic



The above CECT images are from a patient who presented to the ER with a recurrent history of left flank pain. A cursory look shows regions of decreased parenchymal enhancement in the left kidney with inflammatory changes of the left perinephric fat which may favor a diagnosis of pyelonephritis. However, there is subtle retroperitoneal adenopathy (left paraaortic and surrounding the left renal artery). Biopsy revealed primary Ewing's sarcoma of the left kidney.

Thursday, December 20, 2012

Mesenteric Hematoma Revisited



The above CECT images show hazy stranding of the mesentery in a patient with blunt abdominal trauma. Findings are consistent with a mesenteric hematoma, previously discussed here.

Tuesday, December 18, 2012

Imaging the Pancreas


Pancreatic adenocarcinoma carries a poor prognosis. CT is a fine modality for imaging the pancreas and determining the nonresectability of a mass. Pancreatic imaging protocols tend to be biphasic with image acquisition performed in the pancreatic parenchymal and portal venous phases. The pancreatic parenchymal phase involves a scanning delay of 40-70 seconds while the portal venous phase is imaged at a delay of 60-70 seconds. Arterial phase imaging should be reserved for patients requiring CT angiography to evaluate for tumor resectability.


REFERENCES
McNulty NJ, Francis IR, Platt JF, et al. Multi-detector row helical CT of the pancreas: effect of contrast enhanced multiphasic imaging on enhancement of the pancreas, peripancreatic vasculature, and pancreatic adenocarcinoma. Radiology 2001;220:97-102.

Monday, December 17, 2012

Hyperdense MCA Sign



The hyperdense MCA sign refers to high attenuation of a segment of the MCA located in the Sylvian fissure indicating presence of a thromboembolus.  The images again demonstrate a dense right MCA with territorial infarction. 

REFERENCES
Shetty SK. The MCA dot sign. Radiology 2006;24:315-8.

Friday, December 14, 2012

Dialysis Catheter Placement

The Kidney Disease Outcomes Quality Initiative (K/DOQI) outlines vascular access management for hemodialysis patients. Of these guidelines, the following should be taken into consideration by interventional radiologists involved in the placing catheters for access in hemodialysis patients

  1. patient evaluation including history of prior central venous catheters, pacemakers, prior vascular access failure, coagulation disorders, valvular heart disease
  2. tunneled catheters should be placed when dialysis access is needed for greater than 3 weeks
  3. right internal jugular vein access is preferred with the tip of the catheter in the right atrium
  4. catheter related infections should be managed as follows:
    • catheter site infection with negative blood cultures - treat with topical antibiotics; do not remove catheter unless there is no response to topical treatment in which case catheter should be exchanged over a wire to preserve venous access
    • bacteremia - treat with systemic antibiotics appropriate for cultured organism; if patient is clinically unstable remove the catheter; if the patient is clinically stable the catheter should only be removed if the patient is symptomatic (fever, elevated WBC) after 36 hours of treatment with antibiotics

REFERENCES
Patel AA, Tuite CM, Trerotola SA. K/DOQI Guidelines: what should an interventionalist know? Semin Intervent Radiol 2004;21(2):119-24.

Thursday, December 13, 2012

Traumatic Fracture of an Axillofemoral Bypass Graft




A man presented to the emergency room after a motor vehicle accident. CECT showed an axillofemoral bypass graft (red arrow) that was fractured due to blunt trauma (last image) with an expanding anterior abdominal wall hematoma and active extravasation of contrast (higher density in second and third images).

Wednesday, December 12, 2012

Teardrop Bladder


A contrast-filled bladder that has a teardrop shape (also referred to as pear-shaped) indicates circumferential extrinsic compression. The differential diagnosis includes:
  • presence of pelvic fluid
    • hematoma
    • lymphocele
    • urinoma
    • abscess
  • pelvic lipomatosis
    • usually seen in black males with hypertension
  • iliopsoas muscle hypertrophy
  • retroperitoneal fibrosis
  • lymphoma
  • vascular dilatation
    • aneurysm
    • collateral vessel development

REFERENCES
Ambos MA, Bosniak MA, Lefleur RS, et al. The pear-shaped bladder. Radiology 1977;122:85-8.
Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics 2004;24:S247-80.

Tuesday, December 11, 2012

Retroperitoneal Liposarcoma



A rare lesion of the retroperitoneum, liposarcomas are usually very large at presentation and tend to displace adjacent structures as in the above image (bowel is displaced to the right abdomen). The lesions demonstrate fat attenuation on CT, high signal on T1WI, low signal on T2WI, and dark signal on fat suppression sequences. Calcification or ossification within the lesion usually indicates poor prognosis. Since lipomas generally do not occur in the retroperitoneum, liposarcoma should be considered when a retroperitoneal fat containing lesion is seen.


REFERENCES
Craig WD, Fanburg-Smith JC, Henry LR, et al. Fat-containing lesions of the retroperitoneum: radiologic-pathologic correlation. Radiographics 2009;29:261-90.

Monday, December 10, 2012

Periosteal Versus Parosteal Osteosarcoma

Periosteal Osteosarcoma
  • femur, tibia
  • diaphyseal
  • chondroid neoplasm - has high water content
    • lower attenuation than muscle on CT
    • high signal intensity on T2WI
  • broad based soft tissue mass attached to cortex
  • cortical thickening and scalloping
  • periosteal reaction
  • marrow involvement is rare

Parosteal Osteosarcoma
  • femur - usually posterior distal aspect
  • metaphyseal
  • growth tends to be circumferential to bone's surface 
  • cleavage plane separates lesion from the cortex
  • dense osteoid matrix
  • usually has marrow involvement
  • low signal on T1WI and T2WI
    • higher grade lesions may be high signal on T2WI

REFERENCES
Jelinek JS, Murphey MD, Kransdorf MJ, et al. Parosteal osteosarcoma: value of MR imaging and CT in the prediction of histologic grade. Radiology 1996;201:837-42.
Murphey MD, Jelinek JS, Temple HT, et al. Imaging of periosteal osteosarcoma: radiologic-pathologic correlates. Radiology 2004;233:129-38.

Friday, December 7, 2012

Lipomatous Hypertrophy of the Interatrial Septum Revisted



A companion case of lipomatous hypertrophy of the interatrial septum previously discussed here. This lesion can mimic fat containing neoplasms including myxomas, rhabdomyomas, rhabdomyosarcomas, and liposarcomas.


REFERENCES
Fan CM, Fischman AJ, Kwek BH, et al. Lipomatous hypertrophy of the interatrial septum: increased uptake on FDG PET. AJR Am J Roentgenol 2005;184:339-42.

Thursday, December 6, 2012

The Flat Cava Sign Revisited



Recently discussed here, these images show a flattened IVC (better seen on second image, red arrow) in a patient with ischemic small bowel. 

Wednesday, December 5, 2012

SMA syndrome



Superior mesenteric artery syndrome (SMA syndrome) refers to compression of the third portion of the duodenum between the aorta and SMA. The images above show classic CECT findings: there is dilation of the stomach, first and second portions of the duodenum (first image), with narrowing of the duodenum as it crosses the spine (second image) and collapse of the distal duodenum (third image).


REFERENCES
Agrawal GA, Johnson PT, Fishman EK. Multidetector row CT of superior mesenteric artery syndrome. J Clin Gastroenterol 2007;41(1):62-5.

Tuesday, December 4, 2012

Endovascular Management of Placenta Accreta


The placenta accreta spectrum involves abnormal placental implantation. Placenta accreta is implantation of the chorionic villi in the myometrium while increta and percreta refer to implantation through the myometrium and in the serosa respectively. The incidence of placenta accreta is one in 2500 deliveries. Prior history of cesarean section and advanced maternal age are considered risk factors. Placenta accreta is associated with massive blood loss during delivery which could be fatal.

Techniques to minimize intraoperative blood loss focus on reducing arterial flow to the uterus and include extraluminal ligation of the pelvic arteries or endovascular occlusion of the iliac arteries with or without embolization.

Endovascular iliac artery occlusion is performed prior to planned cesarean section and involves puncture of the bilateral femoral arteries with placement of balloon catheters in each internal iliac artery, preferably in its anterior trunk. After the umbilical cord is clamped, the balloons are inflated and remain so until skin closure, occluding the internal iliac arteries and reducing blood flow to the uterus. If endovascular balloon occlusion is not successful at controlling intraoperative hemorrhage, embolization with gelatin sponge particles can be performed. The latter is associated with greater radiation doses to the fetus.

To present date, there are few studies (each with small sample sizes) showing the efficacy of endovascular balloon occlusion techniques in the perioperative management of placenta accreta. However, the existing data demonstrates it to be a safe technique to prevent blood loss in these patients.


REFERENCES
Tan CH, Tay KH, Sheah K, et al. Perioperative endovascular internal iliac artery occlusion balloon placement in the management of placenta accreta. AJR Am J Roentgenol 2007;189:1158-63.

Monday, December 3, 2012

Open Globe Injury



CT signs of open globe injury include change in globe contour and volume, scleral discontinuity, intraocular air, and intraocular foreign body. 

NECT images above show contour deformity of the left globe with high density in the posterior chamber compatible with vitreous hemorrhage. CECT obtained several hours later (third image) shows loss of volume of the left globe. The patient was found to have a ruptured globe after sustaining a penetrating injury.

REFERENCES
Kubal WS. Imaging of orbital trauma. Radiographics 2008;28:1729-39.

Thursday, November 29, 2012

Idiopathic Orbital Inflammatory Syndrome



Orbital inflammatory syndrome (OIS), also known as orbital pseudotumor, is a diagnosis of exclusion when evaluating proptosis. The typical presentation is unilateral, painful proptosis. It is categorized based on region of involvement in the orbit as either diffuse, anterior, lacrimal, myositic, and apical. 

On CECT an enhancing orbital mass is seen.  The mass is hypointense on T1WI and iso- to hyperintense on T2WI. Irregular contrast enhancement is seen with gadolinium. 

The above image demonstrates an enhancing left orbital apical pseudotumor causing proptosis. This should be differentiated from the imaging appearance of Graves Ophthalmopathy


REFERENCES 
Chaudhry IA, Shamsi FA, Arat YO, et al. Orbital pseudotumor: distinct diagnostic features and management. Middle East Afr J Ophthalmol 2008; 15(1):17-27.
LeBedis CA, Sakai Osamu. Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting. Radiographics 2008;28:1741-53.

Wednesday, November 28, 2012

Thoracic Involvement in Amebiasis


  • Amebiasis is an infection due to the protozoan Entamoeba histolytica
  • Most common manifestation is liver abscesses
  • Thoracic involvement is either through direct extension from the liver (most common) or via hematogenous spread
  • Pleural effusions are common, may be an empyema if the effusion is due to a ruptured hepatic abscess
  • Pneumonia with formation of hepatobronchial or bronchobiliary fistula
  • Pericarditis is more common when the left hepatic lobe is involved and can cause cardiac tamponade
  • Invasion of the IVC may cause pulmonary emboli

REFERENCES
Martinez S, Restrepo CS, Carrillo JA, et al. Thoracic manifestations of tropical parasitic infections: a pictorial review. Radiographics 2005;25:135-55.

Tuesday, November 27, 2012

Omental Infarction




The normal appearance of the greater omentum on CT studies is a band of fatty tissue containing vessels that lies anterior to the transverse colon. Omental infarction represents an interruption of the omental arterial supply.  The CT findings of omental infarction are a heterogeneous fatty mass located between the anterior abdominal wall and the colon. Typically, omental infarction occurs in the right abdomen, as in the above case, although in patients with prior abdominal surgery the location is variable.  Associated peri colonic inflammatory changes may be seen.


REFERENCES
Pereira JM, Sirlin CB, Pinto PS, et al. Disproportionate fat standing: a helpful CT sign in patients with acute abdominal pain. Radiographics 2004;24:703-15.

Friday, November 23, 2012

Graves Ophthalmopathy


Graves ophthalmopathy is the most common cause of exophthalmos in adults. The classic imaging finding is enlargement of the extraocular muscles with sparing of their tendinous insertions. These findings tend to be bilateral and symmetric. The above image demonstrates bilateral orbital proptosis and subtle enlargement of the medial and lateral recti muscles bilaterally with sparing of their tendons.

The can be differentiated from orbital pseudotumor which is a cause of unilateral orbital proptosis. In orbital pseudotumor, the extraocular muscles and their tendons are enlarged.


REFERENCES
LeBedis CA and Sakai O. Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting. Radiographics 2008;28:1741-53.

Wednesday, November 21, 2012

Serous Atrophy of Bone Marrow

Diffuse serous atrophy of bone marrow occurs in anorexia nervosa, chronic renal insufficiency, thyroid disease, tuberculosis, HIV, and cachexia related to malignancy. It refers to depletion of red and yellow marrow, absence of marrow fat, and accumulation of hyaluronic acid in the marrow spaces. The increased free water content leads to prolonged T1 and T2 relaxation times. T1W images show intermediate marrow signal while T2W images show very high signal intensity. The typical progression of serous atrophy is from the distal extremities to the proximal extremities and axial skeleton.


REFERENCES
Vande Berg BC, Malghem J, Devuyst O, et al. Anorexia nervosa: correlation between MR appearance of bone marrow and severity of disease. Radiology 1994;193:859-64.

Tuesday, November 20, 2012

Splenic Injury in Blunt Abdominal Trauma



The spleen is the most frequently injured organ in blunt abdominal trauma. Injuries can range from subcapsular hematoma to splenic fracture. On imaging studies a subcapsular hematoma will compress the lateral margin of the spleen. A laceration appears as a hypodense linear cleft through the splenic parenchyma. A fracture is a laceration that extends through the splenic hilum, isolating a fragment of splenic tissue.

The above CECT demonstrates a large subcapsular splenic hematoma causing compression and medial deviation of the spleen. A focus of high density within this hematoma represents active contrast extravasation. Angiogram of the splenic artery shows a blush of contrast near the inferior splenic pole which was successfully embolized with Gelfoam.


REFERENCES
Roberts JL, Dalen K, Bosanko CM, et al. CT in abdominal and pelvic trauma. Radiographics 1993;13:735-52.

Monday, November 19, 2012

The Flat Cava Sign

Flattening of the IVC is most commonly described in patients with abdominal trauma leading to hypovolemia and hypoperfusion of the bowel ("shock bowel."). The IVC is considered "flattened" if its AP diameter is less than 9 mm at the level of the renal veins. Associated imaging findings of the "hypovolemia complex" include decreased caliber of the abdominal aorta, increased enhancement of the bowel mucosa, and prolonged intense enhancement of the adrenal glands.

In pediatric patients the constellation of findings seen with post traumatic shock is called the "hypoperfusion complex." Imaging findings include fluid-filled, dilated bowel; increased enhanced of the bowel wall, mesentery, kidneys, pancreas, adrenal glands, aorta, and IVC; decreased caliber of the aorta and IVC. Presence of these findings indicates a poor prognosis.


REFERENCES
Eisenstat RE, Whitford AC, Lane MJ, et al. The "Flat Cava" sign revisited: What is its significance in patients without trauma? AJR Am J Roentgenol 2002;178(1):21-5.
O'Hara SM, Donnelly LF. Intense contrast enhancement of the adrenal glands: another abdominal CT finding  associated with hypoperfusion complex in children. AJR Am J Roentgenol 1999;173(4):995-7.

Friday, November 16, 2012

Meniscal Flounce Revisited



Previously discussed here, meniscal flounce is a normal variant characterized by a single fold along the free edge of a meniscus. By definition it exists in the absence of a meniscal tear. While usually seen in the medial meniscus, the above images demonstrate the finding on the lateral meniscus. 


REFERENCES
Park JS, Kyung NR, Yoon KH. Meniscal flounce on knee MRI: correlation with meniscal locations after positional changes. AJR Am J Roentgenol 2006;187:364-70.
Yu JS, Cosgarea AJ, Kaeding CC. Meniscal flounce MR imaging. Radiology 1997;203:513-5.

Thursday, November 15, 2012

Post Thrombotic Syndrome


Post thrombotic syndrome (PTS) is a late complication of deep venous thrombosis (DVT) characterized by chronic pain, heaviness, and leg swelling in the effected limb. On physical exam edema, telangectasia, and hyperpigmentation may be seen and in severe cases venous ulceration may develop. The pathophysiology is felt to be an interplay between the presence of an acute thrombus and attempts at vein recanalization leading to valvular incompetence in the weeks following a DVT. This leads to venous hypertension which causes edema and ulceration.

Traditionally, conservative management with compression stockings has been the mainstay of therapy in most patients. Newer endovascular techniques such as iliocaval stenting are becoming more popular especially due to poor patient compliance with traditional therapy. 

Endovascular thrombolysis is evolving as a therapy for DVTs with the hope of preventing the development of PTS. Some of the first endovascular methods were catheter directed thrombolysis (CDT) and percutaneous mechanical thrombectomy (PMT) which were determined to have safety limitations precluding their widespread use. Yet a newer technique called pharmacomechanical catheter directed thrombolysis combines CDT and PMT and is currently being studied in the ATTRACT clinical trial. In this method, intravenous thrombolytic agents are administered and combined with mechanical maceration of clot which further disperses the fibrinolytic drug and accelerates thrombolysis. This helps dissolve clot fragments which would otherwise embolize to the lungs. 

The use of endovascular DVT therapy as first line treatment may improve patient outcomes by prevention of development of PTS.


REFERENCES
Kahn SS. The post-thrombotic syndrome: the forbidden morbidity of deep venous thrombosis. J Thromb Thrombolysis 2006;21(1):41-8.
Vedantham S. Deep venous thrombosis: the opportunity at hand. AJR Am J Roentgenol 2009;193(4):922-7.

Wednesday, November 14, 2012

Enlarged Parietal Foramina




Enlarged parietal foramina are considered a benign normal variant in calvarial ossification. They are associated with anomalies of cerebral venous development, variations in occipital cortical infolding, scalp defects, and cleft palate. Although sometimes palpable, these defects are usually discovered incidentally. For patients with prominent foramina, cerebral vascular imaging may be considered for work up of aforementioned anomalies.


REFERENCES
Fink AM and Maixner W. Enlarged parietal foramina: MR imaging features in the fetus and neonate. AJNR 2006;27:1379-81.
Reddy AT, Hedlund GL, Percy AK. Enlarged parietal foramina: association with cerebral venous and cortical anomalies. Neurology 2000;54(5):1175-8.

Tuesday, November 13, 2012

Red Bone Marrow Reconversion

Bone marrow is primarily red (composed of hematopoietic elements) at birth and converts to yellow with skeletal maturation. The two types of marrow differ in their composition: red marrow is approximately 40% water and 40% microscopic fat, while yellow marrow is approximately 80% fat. This lends to the differing MR imaging appearances of red and yellow marrows.

Reversal of a normal marrow conversion pattern (marrow reconversion) can occur with various stressors. Specifically, reconversion occurs in healthy individuals with changing metabolic demands, for example those enlisting in an athletic training program or altitude climbers. Slightly different is the idea of marrow repopulation which happens in patients with a chronic illness such as sickle cell disease or thalassemia. A third cause of increased red marrow in adults is marrow stimulation which occurs in patients who are receiving red cell and/or granulocyte stimulating factors.

The differential diagnosis for increased red marrow in adults includes marrow deposition disease (Gaucher's), myelofibrosis, leukemia and lymphoma.


REFERENCES
Poulton TB, Murphy WD, Durek JL, et al. Bone marrow reconversion in adults who are smokers: MR imaging findings. AJR Am J Roentgenol 1993;161(6):1271-21.
Zajick DC Jr, Morrison WB, Schweitzer ME, et al. Benign and malignant processes: normal values and differentiation with chemical shift MR imaging in vertebral bodies. Radiology 2005;237(2):590-6.

Monday, November 12, 2012

Penetrating Neck Injuries



Penetrating neck injuries are usually evaluated in zones. 
  • Zone I: 
    • extends from the sternal notch to the cricoid cartilage
    • contents - branches of the inominate artery and brachiocephalic veins, branches of subclavian arteries and veins, common carotid and vertebral arteries, trachea, esophagus, thyroid
  • Zone II:
    • extends from the cricoid cartilage to the angle of the mandible
    • contents - common, internal, and external carotid arteries, larynx, upper esophagus, pharynx
    • most commonly surgically explored
  • Zone III: 
    • extends from the angle of the mandible to the base of the skull
    • contents - internal cartoid, vertebral, and branches of the external carotid arteries, internal jugular vein, pharynx
Due to the various vascular structures in each of the zones, CTA is often used to evaluate neck trauma. 

The above images are from a patient with bilateral penetrating neck injuries (note the subcutaneous and intramuscular emphysema). The second image shows the bifurcation of the left common carotid artery (arrowhead). In more cephlad images, the left internal carotid artery is not opacified (arrowhead, third image). Surgical exploration demonstrated a Zone II injury to the left common carotid artery as well as to the left internal jugular vein.


REFERENCES
Nunez DB, Torres-Leon M, Munera F. Vascular injuries of the neck and thoracic inlet: helical CT-angiographic correlation. Radiographics 2004;24:1087-98.
Steenburg SD, Sliker CW, Shanmuganathan K, et al. Imaging evaluation of penetrating neck injuries. Radiographics 2010;30:869-86.

Thursday, November 8, 2012

Lady Windermere Syndrome



An 88 year old Caucasian woman presents to the ER with hemoptysis. CT scan reveals bronchiectasis in the medial segment of the right middle lobe with scattered peripheral nodules. Findings are typical for  Mycobacterium avium intracellulare complex (MAIC). This is an atypical mycobacterial infection seen in elderly females. It is thought that the imaging findings may be due to chronic suppression of a cough leading to retained secretions in the dependent portions of the ventral lung fields.


REFERENCES
Rossi SE, Franquet T, Volpacchio M, et al. Tree-in-bud pattern at thin-section CT of the lungs: radiologic-pathologic overview. Radiographics 2005;25:789-801.

Wednesday, November 7, 2012

Gastrointestinal Manifestations of Behcet Disease


Behcet disease (BD) is an idiopathic vasculitis affecting multiple organs. Involvement of the GI tract is seen in up to 50% of cases. Specific GI tract manifestations include:

  • ulceration: most common finding
    • localized - usually in the ileocecal region
    • diffuse - usually in the colon
    • ulcers are deep, often penetrating to the serosal layer 
    • recur at surgical anastamotic sites
  • thickened mucosal folds in the small bowel
  • increased incidence of fistulas and perforations
    • microperforations are common due to deep, penetrating nature of ulcers

REFERENCES
Chae EJ, Do KH, Seo JB, et al. Radiologic and clinical findings of Behcet disease: comprehensive review of multisystemic involvement. Radiographics 2008;28:e31.
Chung SY, Ha HK, Kim JH, et al. Findings of Behcet syndrome involving the gastrointestinal tract. Radiographics 2001;21:911-24.

Tuesday, November 6, 2012

Lower Extremity Arterial Trauma



A middle aged male presented with a femur fracture sustained after a tree fell on his leg. After closed reduction of the fracture, peripheral pulses were absent. Diagnostic conventional angiogram demonstrated a dissection of the distal superficial femoral artery at the level of the fracture with no distal reconstitution of the popliteal artery.

Imaging recommendations:
  • perform CT angiography in patients who are stable and have suspected (but not confirmed) arterial injury
    • faster than conventional angiography
    • limitations include poor timing of contrast bolus, streak and motion artifact
  • conventional angiography in patients with strong indication of arterial injury
    • prolongs ischemic time 
    • radiologic intervention is possible and preferred over surgical exploration.


REFERENCES
Miller-Thomas MM, West OC, Cohen AM. Diagnosing traumatic arterial injury in the extremities with CT angiography: pearls and pitfalls. Radiographics 2005;25:S133-42.
Rieger M, Mallouhi A, Tauscher T, et al. Traumatic arterial injuries of the extremities: initial evaluation with MDCT angiography. AJR Am J Roentgenol 2006;186(3):656-64.

Monday, November 5, 2012

Menetrier Disease


  • rare, idiopathic hypertrophic gastropathy
  • patients usually present with epigastric pain and hypoalbuminemia (from loss of albumin into the gastric lumen)
  • bimodal age distribution
    • childhood form thought to be linked to cytomegalovirus infection
  • diagnosis is made by combination of endoscopic and radiologic findings
    • Upper GI series: thickened, lobulated folds in the gastric fundus which trap barium; hypersecretion may dilute barium which may prevent mucosal coating
    • CECT: thickening of mucosa and submucosa which projects into the gastric lumen
  • differential diagnosis
    • Zollinger Ellison Syndrome - rugal fold thickening is not as pronounced, gastric ulcers, pancreatic involvement
    • Gastritis - thickened folds usually in the antrum, H. pylori positive
    • Lymphoma - thickened folds due to soft tissue masses not due to edema

REFERENCES
Friedman J, Platnick J, Farruggia S, et al. Menetrier Disease. Radiographics 2009;29:297-301.
Kanne JP, 

Friday, November 2, 2012

Gonadal Vein Thrombosis


Gonadal vein thrombosis can be a cause of acute pelvic pain. It is most commonly seen in post partum females but may also present in patients after pelvic surgery, pelvic trauma, and pelvic inflammatory disease. There is a predilection for this finding on the right side as retrograde flow through the left gonadal vein prevents stasis. 

On CECT, an enlarged gonadal vein that parallels the course of the psoas muscles with an enhancing wall and an intraluminal filling defect will be seen. Perivenous inflammatory changes may be seen. The patient above is post cesarean section. A filling defect is seen in the right gonadal vein (adjacent to the IVC) consistent with thombosis.


REFERENCES
Bennett GL, Slywotzky CM, Giovanniello G. Gynecologic causes of acute pelvic pain: spectrum of CT findings. Radiographics 2002;22:785-801.

Thursday, November 1, 2012

AV Fistula Planning

In patients with end stage renal disease (ESRD), the ideal venous access for hemodialysis should fulfill three requirements: 1. indefinite life, 2. high flow, 3. no complications such as thrombosis or aneurysm formation. The native arteriovenous (AV) fistula comes closest to fulfilling these requirements and is the best option for venous access. 

In planning for creation of an AV fistula several factors have to be taken into considerations including the patient's vascular history. Patients who have had prior central venous catheters, pacemakers may be poor candidates for AV fistula creation because these procedures are associated with venous stenosis.


REFERENCES
Patel AA, Tuite CM, and Trerotola SO. K/DOQI guidelines: what should an interventionalist know? Semin Intervent Radiol 2004;21(2):119-24.

Wednesday, October 31, 2012

Splenic Sequestration



Splenic sequestration is seen in patients with sickle cell disease. It is due to trapping of red blood cells in the spleen's tortuous microcirculation. During sequestration the spleen is enlarged. On CECT studies (as above), peripheral low attenuation with high attenuation of the hilum is seen. MR imaging may demonstrate patchy areas of abnormal signal intensity on both T1 and T2 weighted images. On T1WI, a hyperintense region with peripheral low intensity will be seen in subacute hemorrhage.


REFERENCES
Lonergan GJ, Cline DB, and Abbondanzo SL. Sickle cell anemia. Radiographics 2001;21:971-94.
Rabushka LS, Kawashima A, and Fishman EK. Imaging of the spleen: CT with supplemental MR examination. Radiographics 1994;14:307-32.

Tuesday, October 30, 2012

The Hurricane Sign


SPECT studies are often used with myocardial perfusion studies for evaluation of ischemia. Long acquisition times for SPECT images increase susceptibility to artifacts, especially those caused by patient motion. The hurricane sign refers to an artifact caused by lateral patient motion during image acquisition. On the short axis views a circular object with spirals extending from the 12:00 and 6:00 positions causing discontinuity in the ventricular walls is seen. This pattern does not correspond with normal coronary artery anatomy.


REFERENCES
Burrell S and MacDonald A. Artifacts and pitfalls in myocardial perfusion imaging. J Nucl Med Technol 2006;34:193-211.
Sorrell V, Figueroa B, Hansen CL. The "hurricane sign": evidence of patient motion artifact on cardiac single photon emission computed tomographic imaging. J Nucl Cardiol 1996;3:86-8.

Monday, October 29, 2012

Emphysematous Pyelonephritis


Emphysematous pyelonephritis (EP) is a life threatening condition with a high overall mortality rate. About 90% of patients presenting with EP have uncontrolled diabetes mellitus. Urinary collecting system obstruction may also be present. E coli is the most common infecting organism. 

Typical US findings are shown above: the renal parenchyma appears echogenic with "dirty" shadowing. CT can confirm the presence of gas.

There is classification of EP into two types based on its CT appearance. Type 1 is characterized by diffuse replacement of the renal parenchyma with gas, without presence of discrete fluid collections. Type 2 EP demonstrates scattered foci of gas with associated regions of fluid attenuation. Type 1 EP carries a worse prognosis and is a surgical emergency.


REFERENCES
Craig WD, Wagner BJ, and Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics 2008;28:255-76.
Grayson DE, Abbott RM, Levy AD, et al. Emphysematous infections of the abdomen and pelvis: a pictorial review. Radiographics 2002;22:543-61.

Friday, October 26, 2012

Benign Neoplasms of the Spleen

  1. Splenic cysts
    • true cyst - has endothelial lining
      • epidermoid
      • parasitic
    • pseudocyst - lacks endothelial  lining 
      • post traumatic - most common
    • both are well defined masses, attentuation similar to water on CT, do not enhance with contrast administration, high signal on T2WI
  2. Hemangioma
    • most common benign neoplasm
    • US: small cystic masses, may show flow on color Doppler
    • CT: hypodense on NCECT, post contrast images show early centripetal nodular enhancement with delayed uniform enhancement
    • MR: hypointense on T1WI, hyperintense on T2WI
    • diffuse hemangiomatosis
      • Klippel-Trenaunay-Weber
      • Kasabach-Merritt-like
      • Beckwith-Weidemann
  3. Hamartoma
    • associated with tuberous sclerosis
    • heterogeneously hyperintense relative to spleen on T2WI
    • diffuse enhancement in early post contrast phase that becomes more uniform on delayed images
  4. Lymphangioma
    • US: well defined, hypoechoic mass, internal septations, may have echogenic debris
    • CT: splenomegaly, single or multiple hypodense masses, may have peripheral calcifications, no enhancement post contrast
    • MR: hypointense T1WI, hyperintense T2WI

REFERENCES
Elsayes KM, Narra VR, Mukundan G, et al. MR imaging of the spleen: spectrum of abnormalities. Radiographics 2005;25:967-82.
Urrutia M, Mergo PJ, Ros LH, et al. Cystic masses of the spleen: radiologic-pathologic correlation. Radiographics 1996;16:107-29.

Thursday, October 25, 2012

Mesenteric Panniculitis


Mesenteric panniculitis is characterized by increased attenuation of an inflamed mesentery with a thin surrounding pseudocapsule. Note the "halo sign" representing spared fat around the mesenteric vessels.

Wednesday, October 24, 2012

Littoral Cell Angioma of the Spleen

  • rare, primary splenic neoplasm
    • littoral cells line the red pulp sinuses in the spleen
  • CECT: 
    • enlarged spleen with innumerable hypoattenuating masses
    • no calcifications
    • no lymphadenopathy
    • no hepatomegaly
  • US:
    • diffuse, coarse, heterogenous echotexture of the spleen
  • Differential diagnosis
    • neoplasms
      • hemangiomas - appear similar but rarely have diffuse involvement, may calcify
        • hemangiomatosis - diffuse splenic hemangioma with same enhancement pattern as hepatic hemangioma
      • lymphoma - look for extra-splenic lymphadenopathy
      • metastatic disease - ovary, breast, endometrium, melanoma
    • granulomatous disease
      • sarcoidosis - increased echogenicity of spleen, + adenopathy
      • TB - look for chest involvement
    • infection
      • disseminated fungal disease
      • septic emboli
      • Kaposi's sarcoma


REFERENCES
Kinoshita LL, Yee J, and Nash SR. Littoral cell angioma of the spleen: imaging features. AJR Am J Roentgenol 2000;174(2):467-9.
Levy AD, Abbott AM, and Abbondanzo SL. Littoral cell angioma of the spleen: CT features with clinicopathologic comparison. Radiology 2004;230:485-90.


Tuesday, October 23, 2012

Portal Vein Varix


Varix of the portal vein is a rare congenital anomaly of unknown origin and refers to focal dilatation of the portal vein. It is sometimes improperly referred to as an aneurysm of the portal vein. The varix is usually asymptomatic and tends to be an incidental finding.

The above images are from a patient who presented with right sided flank pain and was presumed to have renal colic. NCECT demonstrates a portal vein varix with luminal high density consistent with thrombosis.


REFERENCES
Lee WK, Chang SD, Duddalwar VA, et al. Imaging assessment of congenital and acquired abnormalities of the portal venous system. Radiographics 2011;31:905-26. 

Monday, October 22, 2012

Intramedullary Marrow Hyperplasia in Sickle Cell Anemia

Red marrow is present in the fetal skeleton and converts to yellow marrow after birth. In sickle cell anemia (SCA) destruction of RBCs causes anemia which prevents the conversion of red marrow to yellow marrow. The persistent red marrow is seen in all bones of patients with SCA and has pathologic and radiologic consequences. Red marrow stimulation leads to widening of the medullary spaces and cortical thinning which can cause pathologic fractures. Coarse trabeculation and osteopenia may also be seen. Persistent red marrow presents as low signal intensity in osseous structures on T1WI. On skull radiographs the widening of the diploic spaces is a manifestation of bone marrow expansion. The hair on end appearance of the skull is secondary to coarse trabeculation from new bone formation. In the spine, cortical thinning results in biconcave deformities of the vertebral bodies sometimes referred to as the fish-mouth appearance.


REFERENCES
Ejindu VC, Hine AL, Mashayekhi M, et al. Musculoskeletal manifestations of sickle cell disease. Radiographics 2007;27:1005-21.


Friday, October 19, 2012

Secretory Calcifications


Calcifications frequently appear on mammograms and need to be classified as benign or malignant. One  benign pattern is that of secretory calcifications. These calcifications (red arrows above) are smooth, linear or rounded, and radiate towards the nipple (long axis pointed towards the nipple). A branching pattern may be seen. The calcifications may have a radiolucent center indicating the noncalcified ductal lumen. Secretory calcifications are often bilateral and symmetric in distribution. 

The blue arrows show a region of smaller, clustered calcifications which were found to be malignant.


REFERENCES
Sickles EA. Breast calcifications: mammographic evaluation. Radiology 1986;160;289-93.

Thursday, October 18, 2012

Fibrosing Mediastinitis

Fibrosing mediastinitis (FM) is due to abnormal proliferation of collagen and fibrous tissue in the mediastinum. It can present either focally or diffusely with the latter type involving multiple mediastinal compartments. Causes are either idiopathic or secondary to granulomatous infection (Histoplasmosis in the United States). 

FM is the most common benign cause of SVC obstruction. Imaging findings include a hilar or mediastinal mass causing mediastinal widening. The right paratracheal region is the most common location for occurrence of a mass. Focal FM tends to have calcified masses whereas calcification is less common in diffuse FM. 

Differential considerations include:
  • lymphoma
  • bronchogenic carcinoma - usually older patient, doesn't calcify


REFERENCES
Rossi SE, McAdams HP, Rosado-de-Christenson ML, et al. Fibrosing mediastinitis. Radiographics 2001;21:737-57.

Wednesday, October 17, 2012

Dyke Davidoff Masson Syndrome


Dyke Davidoff Masson Syndrome (DDMS) is a neurodegenerative disorder likely due to cerebral injury in utero or early in life. The main finding is cerebral hemiatrophy. Associated findings include ipsilateral compensatory calvarial thickening, enlarged frontal sinus, elevation of the petrous ridge and sphenoid wing.

The above images are from a young boy who presented with a history of seizures. There is asymmetric atrophy of the left cerebral hemisphere. Bone window examination demonstrates enlargement of the left frontal sinus.


REFERENCES
Grossman RI, Yousem DM. Neuroradiology, the requisites. Mosby Inc. (2003)

Tuesday, October 16, 2012

Congenital Midline Nasofrontal Masses

Midline nasofrontal masses are due to faulty regression of the midface dural diverticulum during embryologic development. The differential diagnosis includes:

  • Epidermoid and dermoid cysts
    • dermoid  
      • ectoderm + skin appendages
      • usually midline and tend to occur at the glabella
    • epidermoid
      • ectoderm without skin appendages
      • usually paramidine
  • Nasal gliomas
    • not a neoplasm
    • cerebral heterotopia
    • can be intranasal (lateral nasal wall, middle turbinate, nasal septum) or extranasal (usually at glabella, +/- overlying skin telangectasia)
    • T1WI - isointense/hypointense to gray matter
    • T2WI - hyperintense to gray matter
  • Encephaloceles
    • herniation of intracranial content through a skull defect with a persistent connection to the subarachnoid space
    • high prevalence of associated intracranial abnormalities
      • intracranial cysts, callosal agenesis, interhemispheric lipomas, facial clefts, schizencephaly
    • usually isointense to gray matter on all MR sequences 
      • may be hyperintense on T2WI due to gliosis


REFERENCES
Lowe LH, Booth TN, Joglar JM, et al. Midface anomalies in children. Radiographics 2000;20:907-22.

Monday, October 15, 2012

Gallstone Ileus

video

The above clip demonstrates multiple calculi and air within the gall bladder, dilatation of distal loops of small bowel with relative collapse of the large bowel, and a large gallstone in the distal ileum. Tracing the distal common bile duct reveals a biliary-enteric fistula.

Friday, October 12, 2012

Trapped Periosteum in Physeal Injuries

Physeal injuries are common in the pediatric population and are usually classified by the Salter Harris system. One of the complications of physeal fractures is trapped periosteum. This can render a fracture as irreducible which may result in premature physeal closure. Trapped periosteum is important to recognize on imaging because it requires open reduction to prevent growth disturbances. 

On radiographs and CT with mulitplanar reconstruction, peristent physeal widening > 3mm after closed reduction is suggestive of trapped periosteum. The MRI findings of trapped periosteum have not been adequately described in the literature. A few reports seem to concur that on proton density weighted fat-suppressed images trapped periosteum appears as a low signal band insinuating at the physis. 


REFERENCES
Barmada A, Gaynor T, Mubarak SJ. Premature physeal closure following distal tibia physeal fractures: a new radiographic predictor. J Pediatr Orthop 2003;23:733-9.
Whan A, Breidahl W, Janes G. MRI of trapped periosteum in a proximal tibial physeal injury of a pediatric patient. AJR Am J Roentgenol 2003;181:1397-9.

Thursday, October 11, 2012

Subtalar Dislocation



The above images demonstrate a medial subtalar dislocation (the foot and calcaneus are medially displaced). The mechanism of this injury is usually due to a fall from a height or a severe twisting injury as in the basketball player above who landed on an inverted foot.

Prompt reduction of this injury is necessary because associated damage to the tibial nerve, and posterior tibial artery and veins may be present and long term sequelae of neurovascular injury should be avoided.


REFERENCES
Lawrence SJ and Singhal M. Open hindfoot injuries. J Am Acad Orthop Surg 2007;15(6):367-76.

Wednesday, October 10, 2012

Sclerotherapy for Treatment of Anuerysmal Bone Cysts

Aneurysmal bone cysts (ABCs) are benign expansile lytic bone lesions of unknown origin that occur in the pediatric population. Characteristics of ABCs were previously discussed here.

Typically, the treatment of ABCs involves resection and curettage with or without bone grafting. However, there is a high recurrence rate reported with this treatment method with some studies reporting up to a recurrence rate of greater than 50%.

Surgical resection of ABCs is less favored as an extensive resection may be necessary and may immobilize the patient for a prolonged period. Furthermore, as ABCs are highly vascular lesions, surgical procedures carry the risk of significant blood loss.

Radiotherapy was previously used to treat ABCs but has since been abandoned due to studies demonstrating malignant transformation of the lesions and development of secondary tumors.

The traditional interventional radiology technique of embolization has been used effectively in the treatment of some ABCs. Preoperative selective embolization of the feeding vessel is used to reduce intraoperative blood loss as well as to treat lesions that are surgically inaccessible. Challenges of this therapy include risk of particle embolization to the vertebrobasilar and spinal arterial systems resulting in ischemia to vital structures. Additionally, not all ABCs have a feeding vessel that can be selectively embolized. 

More recently, studies have shown intralesional sclerotherapy to be an effective treatment for ABCs. Sclerosing agents act by damaging the endothelial lining which leads to activation of the coagulation cascade and thrombotic vascular occlusion. Agents that have been used for sclerotherapy include ethanol based solutions, methylprednisone, calcitonin, and doxycycline. Patients usually require several injections of the agent. Post procedure imaging typically shows sclerosis of the lesion with long term complete ossification. Patients have reported a relief of symptoms and low recurrence rates have been reported. This data suggests that image guided sclerotherapy of ABCs may be a safe, minimally invasive method of treating these lesions. 



REFERENCES
Rai AT and Collins JJ. Percutaneous treatment of pediatric aneurysmal bone cyst at C1: a minimally invasive alternative: a case report. AJNR Am J Neuroradiol 2005;26:30-3.
Rastogi S, Varshney MK, Trikha V, et al. Treatment of aneurysmal bone cysts with percutaneous sclerotherapy using polidocanol. J Bone Joint Surg [Br] 2006;88-B:1212-6.


Tuesday, October 9, 2012

Epiploic Appendagitis



Epiploic appendages are peritoneal outpouchings attached to the serosal surface of the colon that contain fat and blood vessels. They occur anywhere from the cecum to the sigmoid, are largest in the sigmoid, and are generally only visible when they are inflamed (i.e. if surrounded by ascites). Torsion of an epiploic appendage or thrombosis of its central vein causes epiploic appendagitis. 

Patients typically present with acute abdominal pain, usually in the left lower quadrant which often leads to its being mistaken for acute diverticulitis (it may be mistaken for acute appendicitis if a cecal epiploic appendage is involved).

CECT will demonstrate an ovoid, fat containing mass adjacent to the anterior colonic wall. Surrounding inflammatory changes are typically seen. A hyperattenuating ring around the mass may be seen. The central dot sign - presence of central high attenuation representing the thrombosed vein - is seen in a minority of cases. Reactive thickening of the adjacent colon may be seen.

The above images are from a patient who presented to the emergency room and was worked up for acute diverticulitis. No colonic diverticula were seen. Instead, in the left lower quadrant there is an ovoid, fat containing mass with inflammatory changes and the central dot sign (arrow). The findings are compatible with epiploic appendagitis.


REFERENCES
Rao PM and Novelline RA. Primary epiploic appendagitis. Radiology 1999;210:145-8.
Singh AK, Gervais DA, Hahn PF, et al. Acute epiploic eppendagitis. Radiographics 2005;25:1521-34.