False Perpetuations: Ovarian Torsion, Doppler Ultrasound, and CT

Contrast-enhanced CT (top) and gray-scale US (bottom) in the same patient, both modalities demonstrating right ovarian torsion. Note the enlarged and heterogenous right ovary, peripheral follicles, and ascites

• False Perpetuation: After a normal CT for lower abdominal or pelvic pain, an ultrasound with color Doppler is necessary to "rule out ovarian torsion"

• Ovarian/adnexal torsion is caused by complete or partial rotation of the ovarian pedicle on its long axis. This results in lymphatic and venous congestion, inturn limiting arterial inflow
• Torsion of both the ovary and fallopian tube occurs more often than that of either structure alone
• Occurs more frequently on the right

• Findings on Ultrasound
• Enlarged ovary
• Eccentric mass (usually a cyst) serving as a lead point
• Round/'full' ovary with a central 'ground glass' appeaerance
• Peripheral follicles
• The presence of (or decrease in) arterial/venous flow predicts a better outcome
• The absense of ovarian flow suggests necrosis
• Even if there is ovarian flow on Doppler imaging, there can still be torsion
• One study (J Ultrasound Med 2001; 20:1083-1089) evaulated the use of Doppler in pathologic proven cases of ovarian/adnexal torsion and found:
• No arterial or venous flow in 40% of cases
• No venous flow, decreased arterial flow in 7% cases
• No arterial flow, decreased venous flow in 33% cases
• Decreased arterial and venous flow in 13% cases
• Normal arterial and venous flow in 7% cases
• A meta-analysis (Eur J Pediatr Surg 2015; 25:82-86) looked at different modalities in diagnosing ovarian torsion in pediatric patients. Regarding morphologic and Doppler criteria on ultrasound for the diagnosis of ovarian torsion, this study found:
• Morphologic features: 92% sensitive and 96% specific
• Some of the morphologic features reviewed:
• Enlarged heterogenous ovary (compared to contralateral normal ovary)
• Ovarian volume 12x larger than contralateral volume, or 75 mL absolute ovarian volume
• Ovarian diameter 2.3x larger than contralteral diameter
• Multiple peripheral cortical follicles with transudative fluid
• Whirlpool-sign
• Cystic mass, particularly > 5cm in diameter
• Doppler: 55% sensitive and 87% specific
• Thus, the diagnosis of ovarian torsion is made or excluded based on grayscale appearance, not the Doppler findings

• Regarding CT and ovarian torsion
• One study (Abdom Imaging 2015; 40:3206-3213) retrospectively evaluated the utility of Doppler ultrasound in the assessment of ovarian torsion following a negative contrast-enhanced CT (the ultrasound and CT were performed within a 24 hour period) found:
• Of the 48 cases with ovarian enlargement (defined as greater than 5 cm), 11 had torsion
• Of the 235 cases without ovarian enlargment, 0 had torsion
• Other CT findings assessed:
• Presense of free fluid
• Uterine deviation
• Fallopian tube thickening
• Smooth wall thickening of a cystic mass
• Ovarian fat stranding
• Twisted Pedicle
• Abnormal ovarian enhancement
• The most common ultrasound finding associated with ovarian torsion was ovarian enlargement (either due to the enlarged ovary itself or a mass functioning as a lead point)
• A completely negative CT was never associated with a Doppler ultrasound suspicious for ovarian torsion (negative predictive value of 100%)
• There is no utility in the addition of a Doppler Ultrasound (specifically for the evaluation of ovarian torsion) following a negative contrast-enhanced CT of the abdomen and pelvis
• Ovarian size should be used as a dominant feature in the exclusion of ovarian torsion on both CT and US

*This blog was inspired by and based on a workshop given at the Society of Abdominal Radiology 2018 annual meeting by Dr. Maitray D. Patel of Mayo Clinic Arizona

Persistent Sciatic Artery

Axial and coronal CT images with intravenous contrast demonstrate a left persistent sciatic artery (long arrows) coursing through the greater sciatic notch and deep to the gluteus maximus muscle. Note the asymmetrically diminutive left external iliac artery (short arrows)

• A persistent sciatic artery (PSA) is a rare vascular anomaly in which the internal iliac artery courses through the greater sciatic notch and in to the thigh
• During embryonic development, the sciatic artery usually involutes as the femoral artery develops
• Recognition of an unusually enlarged internal iliac artery and a diminutive external iliac artery are some clues in diagnosing a PSA
• The PSA course runs close to the sciatic nerve, and can run within the nerve sheath in some cases
• Distally, the PSA runs deep to the gluteus maximus muscle, coursing along the adductor magnus muscle
• Reported in up to 0.03-0.06% of the population and can be bilateral in 20% of cases
• PSA is considered complete when it is the dominant blood supply to the popliteal artery and incomplete with the femoral artery is the dominant blood supply to the popliteal artery
• 5 types have been described:
• type 1 is a complete PSA with a normal femoral artery
• type 2 is a complete PSA with a incompletely developed femoral artery
• type 3 is a incomplete PSA (only the cephalic portion is present) and normal femoral artery
• type 4 is a incomplete PSA (only the caudal portion is present) and normal femoral artery
• type 5 is when the PSA arises from the median sacral artery
• Majority (80%) become symptomatic at some point presenting with intermittent claudication, ischemia, pulsatile mass or neurologic symptoms
• Susceptible to repetitive trauma from sitting and hip flexion/extension
• Results in premature atherosclerosis and aneurysm formation
• Aneurysm found in 48%, and stenosis and occlusion of the PSA in 7% and 9%, respectively

References:

1. Mcquaid M, Gavant ML. Posttraumatic pseudoaneurysm of a persistent sciatic artery. AJR Am J Roentgenol. 1995;164 (6): 1514-5. 
2. Pillet J, Albaret P, Toulemonde JL, Cronier P, Raimbeau G, Chevalier JM. Tronc arteriel ischiopoplite, persistance de l’artere axiale. Bull Assoc Anat 1980;64:109e22.
3. Pillet J, Cronier P, Mercier Ph, Chevalier JM. The ischio popliteal arterial trunk: a report of two cases. Anat Clin 1982; 3:329e31. 
4. Gauffre S, Lasjaunias P, Zerah M. Sciatic artery: a case, review of literature and attempt of systematization. Surg Radiol Anat 1994;16(1):105e9.
5. Bower EB, Smullens SN, Parke WW. Clinical aspect of persis- tent sciatic artery: report of two cases and review of the literature. Surgery 1977;81(5):588e95.

Dilated Cisterna Chyli: A Potential Mimicker of Lymphadenopathy

  

Axial (top) and coronal (bottom) contrast-enhanced CT images
demonstrate a retrocrural fluid-filled tubular structure with imperceptible walls
 (black arrows), the classic imaging features of a cisterna chyli

Coronal T2-weighted MRI shows the tubular cystic structure of the cisterna chili
and it's continuity with the thoracic duct (white arrow)

• The cistern chyli is a dilated lymphatic sac ommonly located in the right retrocrural region, at the level of L1-L2, extending 5-7 cm in CC dimension. It classically receives draining lymph from two lumbar trunks and an intestinal trunk, and continues cephalad as the thoracic duct

• Can enhance on delayed MRI >5 min

• Has an average size of 7.4 mm in the AP dimension, although some authors consider it dilated when ≥6 mm

• Dilatation can be secondary to lymphatic damage from prior gastroesophageal or retroperitoneal surgery, uncompensated cirrhosis, hypoalbuminemia, lymphangioleiomyomatosis, elevated central venous pressure, and biliary obstruction

• Size changes can vary depending on phase of respiration, hydration, and lower thoracic duct peristalsis

• Important to know of this entity because it can mimic retrocrural lymphadenopathy in the oncologic setting

• Mulitplanar reformations and MRI can help demontrsate the tubular cystic nature of the cistern chyli and its continuity with the thoracic duct 

References 

1. Rosenberger A, Abrams HL (1971) Radiology of the thoracic duct.Am J Roentgenol Radium Ther Nucl Med 111:807–820
2. Pinto PS, Sirlin CB, Andrade-Barreto OA, et al. (2004) Cisternachyli at routine abdominal MR imaging: a normal anatomicstructure in the retrocrural space. Radiographics 24(3):809–817 
3. Smith TR, Grigoropoulos J (2002) The cisterna chili: incidence and characteristics on CT. Clin Imaging 26:18–22
4. Arrive ́ L, Azizi L, Lewin M, et al. (2007) MR lymphography ofabdominal and retroperitoneal lymphatic vessels. AJR189(5):1051–1058
5. Gollub MJ, Castellino RA (1996) The cisterna chyli: a potentialmimic of retrocrural lymphadenopathy on CT scans. Radiology199(2):477–480 

Re

Keloids and Hypertrophic Scars

T1 axial post-contrast MRI of a keloid or hypertrophic scar formation along the margins of a myocutaneous flap. The enhancement can fool you into thinking that there is recurrent tumor, but the linear pattern along the flap margin is the clue that this is related to the scar.

Keloids and hypertrophic scars are fibroblastic proliferations of the dermis. Their morphologic and pathologic features overlap. They are associated with trauma, infection, and connective tissue diseases. They do not spontaneously regress and tend to recur after surgical excision, so surgery is often combined with topical corticosteroid injection or, less commonly, radiation therapy.

In contrast to hypertrophic scars, keloids tend to grow beyond the margins of the injury site, have keloid collagen, and are less likely to stain for smooth muscle actin. Keloids have a higher recurrence rate than hypertrophic scars.

Keloids are hypocellular and are composed of dense collagen. The abundance of type I collagen results in low T2 signal. Keloids occur most frequently in patients aged 15–45 years. People of African and Chinese origin have a higher predilection for keloids. The face, shoulders, forearms, and hands are most commonly affected. They tend to occur where there is increased skin tension

References

Dinauer PA, Brixey CJ, Moncur JT, Fanburg-Smith JC, Murphey MD. Pathologic and MR imaging features of benign fibrous soft-tissue tumors in adults. Radiographics. 2007 Jan-Feb;27(1):173-87.

Ventriculus Terminalis

The ventriculus terminalis (also known as the terminal ventricle and the fifth ventricle) is a rarely identified cerebrospinal fluid cavity within the conus medullaris. The ventriculus terminalis does not communicate with the subarachnoid space or the central canal of the spinal cord, and may actually be an embryonal remnant of the primitive central canal, leading some to refer to it a sinus terminalis instead.

They are occasionally associated with caudal regression of the spinal cord, Chiari type I malformation, lipomyelomeningoceles, and lumbosacral "lipomas." Some authors believe that all of us have some sort of cystic CSF space at the conus medullaris, but that it's simply larger [and detectable on imaging] in some people and tends to regress (but not completely resolve) over time.

The characteristic imaging features are more commonly seen in children: Cystic lesion of the conus medullaris without spinal cord signal abnormality. In adults, ventriculus terminalis is more likely to have septations and be associated with spinal cord edema, kyphotic deformity and spinal arteriovenous malformations.

Rarely, ventriculus terminalis can enlarge in the presence of meningeal hemorrhage or deformities of the vertebral canal. An enlarged or symptomatic ventriculus terminalis can be treated by cyst fenestration with or without shunting to the subarachnoid space, pleural cavity, or peritoneal cavity.

References

• Kernohan JW. The ventriculus terminalis: its growth and development. J Comp Neurol 1924;38:107–125.
• Suh SH, Chung TS, Lee SK, Cho YE, Kim KS. Ventriculus terminalis in adults: unusual magnetic resonance imaging features and review of the literature. Korean J Radiol. 2012 Sep-Oct;13(5):557-63.
• Woodley-Cook J, Konieczny M, Spears J. The Slowly Enlarging Ventriculus Terminalis. Pol J Radiol. 2016 Nov 7;81:529-531.

The Cervical Split: A Pseudofracture

A horizontal line projecting over a cervical vertebral body on lateral radiographs can simulate a fracture or a butterfly vertebral body. This pseudofracture, the so-called cervical split, can result from the lucency between contiguous uncovertebral osteophytes, or, as in the case above, cervical scoliosis resulting in projection of the facet joint over the vertebral body.

A cervical split due to uncovertebral joint osteophyte formation is said to be always accompanied by disc space narrowing.

References

• Goldberg RP, Vine HS, Sacks BA, Ellison HP. The cervical split: a pseudofracture. Skeletal Radiol. 1982 Jan;7(4):267-72.
• Patinharayil G1, Han CW, Marthya A, Meethall KC, Surendran S, Rudrappa GH. Butterfly vertebra: an uncommon congenital spinal anomaly. Spine (Phila Pa 1976). 2008 Nov 15;33(24):E926-8.

Chronic Subperiosteal Iliac Hematoma

Subperiosteal iliac hematoma is caused by traumatic avulsion of the periosteum in children and young adults. The loose attachment of periosteum in young patients allows it to be displaced by hematoma in trauma. In the chronic phase, it is typically incidentally discovered by radiologists.

In the chronic phase, it presents as a lens-shaped ossified process on the internal aspect of the iliac wing with a ghost cortex (dotted line in the image above). It may or may not have the well-defined central lesion we have in this case.

References

Guillin R, Moser T, Koob M, Khoury V, Chapuis M, Ropars M, Cardinal E. Subperiosteal hematoma of the iliac bone: imaging features of acute and chronic stages with emphasis on pathophysiology. Skeletal Radiol. 2012 Jun;41(6):667-75.

Mimicker: Inguinal Mesh Plug

Left inguinal mesh plug with a lobular contour

Left inguinal mesh plug. Note conical morphology on this coronal MPR.

• Depending on the inguinal hernia repair method chosen, a mesh plug can be used for reinforcement. One such method uses a polypropylene (Prolene) plug
• The post-operative appearance of an inguinal mesh plug can masquerade as an inguinal mass or lymphadenopathy

Imaging Findings

• On CT, mesh plugs can have a slightly nodular or smooth outline. The density is similar to sightly lower than muscle. Mesh plugs have also been reported as a ring-like density with central fat attenuation, potentially mimicking epiploic appendicitis if on the left
• On MRI, mesh plugs are typically T1 hypointense and demonstrate variable T2 weighted signal
• Due to a granulomatous reaction, mesh plugs can be FDG avid

Helpful hints in preventing misdiagnosis

• Mutliplanar reformations can be useful in demonstrating the conical morphology of the mesh plug, although they can appear ovoid 
• Postsurgical changes including skin thickening and suceptabliity artifact can also be helpful imaging features

References

The British Journal of Radiology, 77 (2004), 261–265
J Comput Assist Tomagr. 2008Jul-Aug;32(4):529-32.
American Journal of Roentgenology. 2010;195: 701-706.

Suspected Type I Rotatory Atlatoaxial Subluxation in Asymptomatic Patients

In an earlier post on rotatory atlatoaxial subluxation, we discussed the Fielding and Hawkins classification, and its application to symptomatic patients (e.g., those with torticollis). Here, we discuss the challenge of making a diagnosis of rotatory atlatoaxial subluxation in unselected patients.

That is, what do you do if your neck or c-spine CT scan is obtained with the head turned, and you see what looks like a Type I rotatory atlatoaxial subluxation?

The patient below was referred to our institution in a cervical collar for management of atlantoaxial rotatory subluxation.

30-year-old man: Thick reconstructions centered at C1-C2 from a CTA obtained with the head rotated to the left. There is apparent type I atlantoaxial rotatory subluxation.
 
Let's take a look at what we know:

• Normal maximum rotation of the head on body is between 60–80°.
• Normal maximum rotation of C1 on C2 makes up for about half of that: 30–45° (although some sources say it can be up to 50°).
• Cutoff for abnormal C1-C2 rotation: >45° or >56°, depending on source.

Looking at our image above, our rotation of C1 on C2 is about 30 degrees, which puts it in the normal range. But, what if the number was higher? How well do we do as radiologists in correctly identifying this as normal?

One study that was helpful came from the forensic field. Pathologists had noted that CTs of cadavers, which are impossible to position "correctly," were resulting in a lot of over-calling of atlantoaxial rotatory subluxation. When they looked at their data they found:

• 19 cases where the C-spine was stable on autopsy. In those 19, 13 had suspected rotatory subluxation based on on CT (false positives)
• The C1-C2 angle in those 13 false positives were between 16–47°.
• All false positives were type I.
• 2 cases where the C-spine was unstable at autopsy. In those 2 cases, 1 had suspected rotatory subluxation on CT (true positive).
• The C1-C2 angle in the 1 true positive was 42°.
• There was a significant association between the false positives and degree of head rotation.

Generalizing this cadaveric study suggests that we need to be careful in calling type I atlantoaxial rotatory subluxation in asymptomatic patients who simply happen to have their head turned in the scanner. This supports the conclusions from a study in living, asymptomatic patients, where the authors showed that incomplete rotational facet displacement on CT was not sufficient to define subluxation.

References

• Fielding JW, Hawkins RJ. Atlanto-axial rotatory fixation. (Fixed rotatory subluxation of the atlanto-axial joint). J Bone Joint Surg Am. 1977 Jan;59(1):37-44.
• Persson A, Falk J, Berge J, Jackowski C. Atlanto-axial rotatory subluxations in postmortem CT: radiologists be aware of a common pitfall. Forensic Sci Int. 2013 Feb 10;225(1-3):9-14.
• Mönckeberg JE1, Tomé CV, Matías A, Alonso A, Vásquez J, Zubieta JL. CT scan study of atlantoaxial rotatory mobility in asymptomatic adult subjects: a basis for better understanding C1-C2 rotatory fixation and subluxation. Spine (Phila Pa 1976). 2009 May 20;34(12):1292-5.

Endologix Stent-graft

Arterial phase CT shows smoothly marginated contrast extending beyond the confines of the metal struts of the stent

Delayed CT shows the smoothly marginated contrast extending beyond the confines of the metal strut unchanged in size and configuration when compared to arterial phase imaging

Most endostent devices used for endovascular repair of aortic aneurysms have the graft material sutured on the luminal side of the stent. The AFX endostent device (Endologix, Irvine, California) is different from other devices in that the graft material is sutured on the outside of the metal component, attached only at the proximal and distal ends.

By intent, the graft material of the AFX stent-graft can separate from the metal struts where it is not directly apposed to the aortic wall.  During surveillance with contrast-enhanced imaging of patients who have reviewed this device, contrast can be detected outside of the metallic construct. Although this finding can imply a type 1 or 3 endoleak when identified with other endostents, it is a normal finding with the AFX device.

Avoiding misinterpretation as an endoleak can be achieved by confirmation of the type of endostent device used for aneurysm repair. In addition, the contrast extending beyond the metal struts does not change in configuration or size on delayed imaging.

References:

J Vasc Interv Radiol. 2012 Nov;23(11):1544-6.

Radiographic Appearance of the Ascenda® 8780 and 8781 Intrathecal Catheters

The Ascenda® 8780 and 8781 intrathecal catheters are 3T MR conditional catheters and have a metallic marker in their catheter connectors that has the potential to be confused for a foreign body (it looked like a needle to me).

The metallic piece is inside the catheter connector. The connector is placed between the pump and spinal segments of the catheter and gives the user an audible and tactile confirmation of secure connection of the catheter segments.

A linear metallic object that is contiguous with the catheters on both views can help differentiate this from a retained foreign object.

The bottom image is from the Ascenda Manual

References

Ascenda Manuals and Technical Resources. Medtronic.

Sarcoid-Like Reaction in Oncology

Sarcoid is thought to develop in predisposed individuals by a cross-reaction to tumor, bacterial, viral, or inorganic antigens or immunogenes. Patients respond by forming noncaseating granulomas, which are most commonly intrathoracic. Sarcoid-like reaction (SLR) refers to the development of noncaseating granulomas in patients who do not fulfill the criteria for systemic sarcoidosis.

In oncological patients, SLR most commonly occurs in the lymph nodes draining a malignant tumor, but can also be observed in the organ of tumor origin and distant tissues. It develops after antineoplastic treatment with biologic modifiers (e.g., interferon and interleukin-2), single or combination chemotherapy agents, or even after surgery without chemotherapy.

The patient above has a history of melanoma of the left lower extremity with recurrent ipsi- and contra-lateral inguinal nodal involvement that has been treated with surgery (most recently 8 months ago) and chemotherapy in the remote past (cisplatin, vinblastine, and dacarbazine). The PET from 3 months ago (left panel) was clear. The new PET (right panel) shows new supraclavicular (red arrow), intra-thoracic (yellow arrows), and upper abdominal (blue arrow) adenopathy. The lymph nodes are highly FDG-avid and most prominent in the chest, where we see the symmetric hilar and mediastinal adenopathy typical of sarcoid and would be atypical for nodal involvement from lower extremity melanoma. It is important to keep SLR in mind in order to avoid over-calling disease progression. This can be more problematic in cases of intrathoracic neoplasms that would be expected to recur in the chest and involve hilar and mediastinal lymph nodes. Symmetrical hilar involvement can be a helpful hint in these cases.

References

• Inoue K, Goto R, Shimomura H, Fukuda H. FDG-PET/CT of sarcoidosis and sarcoid reactions following antineoplastic treatment. Springerplus. 2013 Dec;2(1):113.
• Tchernev G, Tana C, Schiavone C, Cardoso JC, Ananiev J, Wollina U. Sarcoidosis vs. Sarcoid-like reactions: The Two Sides of the same Coin? Wien Med Wochenschr. 2014 Jul;164(13-14):247-259.

Iatrogenic Pneumocephalus

Axial NECT images from a female patient who presented with a headache 6 hours post partum demonstrate air outlining the anterior horns of the lateral ventricles. The patient received epidural anesthesia during labor which is the most likely cause of this imaging appearance.


REFERENCES
Zak IT, Dulai HS, Kish KK. Imaging of neurologic disorders associated with pregnancy and the post partum period. Radiographics 2007;27:95-108.

Isodense Subdural Hematoma

The above NECT images demonstrate a right sided extra-axial crescentic collection that has similar attenuation to gray matter. The collection causes effacement of right sided sulci, and mass effect with midline shift. The isodensity to underlying cortical tissue makes this consistent with an isodense/subacute subdural hematoma indicating that its age ranges from ~3 days to 3 weeks. In patients with anemia, an isodense subdural hematoma can occur in the acute setting.


REFERENCES
Kim KS, Hemmati M, Weinberg PE. Computed tomography in isodense subdural hematoma. Radiology 1978;128:71-4.

Traumatic Aortic Transection

The above images are from a patient who suffered a motor vehicle accident. The axial image demonstrates a mediastinal hematoma and an intimal flap in both the ascending and descending aorta. The sagittal image better demonstrates the continuity of the intimal flap along with aortic contour abnormality. These findings are pathognomonic for acute traumatic aortic injury.

A finding that is not demonstrated on these images is active extravasation of intravenous contrast material. Its presence would be concerning for exsanguination. 


REFERENCES
Kuhlman JE, Pozniak MA, Collins JC, et al. Radiographic and CT findings of blunt chest trauma: aortic injuries and looking beyond them. Radiographics 1998;18:1085-1106.
Steenburg SD, Ravenel JG, Ikonomidis JS, et al. Acute traumatic aortic injury: imaging evaluation and management. Radiology 2008;248:748-62.

Dural Sinus Thrombosis

Dural sinus thrombosis (DST) is a venous occlusion likely secondary to increased intracerebral venous pressure. The classic sign on NCECT is hyperdense thrombus in the occluded sinus. CECT may demonstrate the empty delta sign: a filling defect that represents the thrombus surrounding by dural enhancement and collateral venous circulation. The MRI findings in DST are discussed here.

The first two images above demonstrate hyperdensity in superior sagittal sinus and torcular herophili. A left temporal lobe intraparenchymal hemorrhage is also noted. CT venogram (third image) demonstrates abrupt cut off at the level of the mid sagittal sinus that continues posteriorly. 

REFERENCES

Leach JL, Fortuna RB, Jones BV, et al. Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls. Radiographics 2006;26:S19-41.

Blunt Diaphragmatic Rupture

Traumatic blunt diaphragmatic rupture (BDR) is most commonly due to motor vehicle accidents (as was the case in the above patient). The left hemidiaphragm is more commonly injured than the right due to protective effects of the liver. Prompt diagnosis of BDR is important due to potentially life threatening complications if this injury is missed. Common signs indicating BDR on plain films and CT are as follows:

Radiographic signs:

• loss of diaphragmatic continuity
• intrathoracic herniation of a hollow viscus (stomach, bowel) or solid organ (liver, spleen)
• visualization of nasogastric tube tip in thorax
• collar sign - focal constriction of a herniating viscus at the site of diaphragmatic tear

CT signs:

• discontinuity of diaphragm
• collar sign (as above)
• dependent viscera sign - herniated viscera is no longer freely suspended in the abdominal cavity and falls dependently (along the posterior ribs)

REFERENCES
Desir A and Ghaye B. CT of blunt diaphragmatic rupture. Radiographics 2012;32:477-98.
Iochum S, Ludig T, Walter F, et al. Imaging of diaphragmatic injury: a diagnostic challenge?. Radiographics 2002;22:S103-16.

Emphysematous Pancreatitis

Acute pancreatitis can progress to emphysematous pancreatitis when superinfection with a gas forming organism occurs. Other causes for intraductal or parenchymal pancreatic gas include end organ infection, enteric fistula, iatrogenic (post endoscopic instrumentation), and reflux from the duodenum after sphincterotomy. The diagnosis carries a poor prognosis and requires aggressive treatment with antibiotics with possible debridement or drainage.

CT is the best modality to detect emphysematous pancreatitis. In addition to retroperitoneal air within and surrounding the pancreas (as on the above images), complications such as abscess formation and necrosis may seen.

The liver findings on the above images are discussed here.


REFERENCES
Grayson DE, Abbott RM, Levy AD, et al. Emphysematous infections of the abdomen and pelvis: a pictorial review. Radiographics 2002;22:543-61.

Intraperitoneal Migration of an Intrauterine Device

As intrauterine devices have become a common form of contraception worldwide, their normal and abnormal imaging appearance should be recognized. The stem of a properly positioned intrauterine device (IUD) should be entirely within the endometrial cavity with the arms extending laterally at the uterine fundus. The device should never be seen in the endocervical canal.

An IUD may be expulsed from the uterine cavity or displaced within it. Perforation through the uterus and migration into the peritoneal cavity is a rare complication. An intraperitoneal IUD may cause bowel/omental adhesions, abscess formation, or perforation of intraabdominal structures. Timely surgical intervention can prevent these complications.


REFERENCES
Boortz HE, Margolis DJA, Ragavendra N, et al. Migration of intrauterine devices: radiologic findings and implications for patient care. Radiographics. 2012 March;32:335-52.
Peri N, Graham D, Levine D. Imaging of intrauterine contraceptive devices. J Ultrasound Med 2007;26(10):1389-1401.
Images courtesy of Anna Nazarenko, M.D.

Mercury Emoblism to the Lung

Nonthrombotic pulmonary emboli are rare and the imaging findings are specific to the origin of the embolus. Types of nonthrombotic emboli include septic emboli, fat emboli, amniotic fluid emboli, and air emboli. Iodinated oil emboli have been reported after transcatheter chemoembolization of hepatocellular carcinoma. Substances such as talc used in preparation of amphetamines by drug addicts can also embolize to the pulmonary arterial tree.

The above image is from a patient who attempted suicide via intravenous mercury injection. The xray image shows multiple metallic spherules throughout both lungs which is the typical imaging appearance for mercury emboli.


REFERENCES
Han D, Lee KS, Franquet T, et al. Thrombotic and nonthrombotic pulmonary arterial embolism: spectrum of imaging findings. Radiographics. 2003 November;23:1521-39.
Rossi SE, Goodman PC, Franquet T. Nonthrombotic pulmonary emboli. AJR Am J Roentgenol 2000;174:1499-1508.