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
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


  • 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

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.

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. 

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

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

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.

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

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.

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).

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.

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.

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