Colovesicular Fistula

A middle aged male presented to the emergency room with acute abdominal pain. CECT revealed sigmoid diverticulitis. A focus of air was also seen within the bladder. 3D reformatted images demonstrated a fistulous connection between the sigmoid colon and bladder (best seen on the second and third images above). The diagnosis of colovesicular fistula was made.

Colovesical fistulas arise most often in the setting of diverticular disease. Findings that suggest fistula formation on CT include intravesical air, bladder wall thickening and perivesicular inflammatory changes. The precise fistulous connection is not always visualized.

In addition to diverticulitis, colovesicular fistulas can occur in the setting of inflammatory bowel disease, gastrointestinal or genitourinary neoplasms, radiation therapy, pelvic surgery, and foreign body impaction.


REFERENCES
Yu NC, Raman SS, Patel M, et al. Fistulas of the genitourinary tract: a radiologic review. Radiographics 2004;24:1331-52.

Intracranial Hypotension and Diffuse Dural Enhancement

Intracranial hypotension refers to decreased CSF pressure leading to a headache (usually orthostatic). The four main imaging findings are:

1. downward displacement of the midbrain
2. diffuse, smooth dural enhancement
3. distended dural sinuses
4. subdural hematoma or hygroma

Absence of one of these signs does not preclude the diagnosis.

The dural enhancement in intracranial hypotension is pachymeningeal (dura-arachnoid) and is seen along the inner table of the skull, as opposed to leptomeningeal enhancement (arachnoid-pia) which is seen on the surface of the brain.

The differential for dural enhancement includes:

1. meningitis - leptomeningeal enhancement
2. dural metastases - scattered, "bumpy" enhancement
3. granulomatous disease (sarcoid, TB) - nodular enhancement
4. meningioma with focal enhancement of the dural tail
5. postoperative changes - transient

REFERENCES

Smirniotopoulous JG, Murphy FM, Rushing EJ, et al. Patterns of contrast enhancement in the brain and meninges. Radiographics 2007;27:525-51.

Tonsilloliths

Tonsilloliths are stones that form in the crypts of the palatal tonsils. Most patients with tonsilloliths are asymptomatic and the finding is made incidentally, as in the patient above (multiple coarse calcifications in the bilateral tonsils). However, large tonsilloliths may cause obstruction leading to infection with possible abscess formation. Thus, the presence of tonsilloliths, even if incidental, should be reported.


REFERENCES
Mody RN and Srivastava S. Bilateral multiple tonsilloliths. Oral Radiology 2009;25(1):67-70.

Tumors Identified via Selective Catheterization of the External Carotid Artery

1. Juvenile nasopharyngeal angiofibroma:

• young boys presenting with epistaxis 
• vascular hamartoma
• embolization is therapeutic

2. Carotid body paraganglioma:

• found at the bifurcation of the carotid artery where they splay its internal and external branches
• prolonged, intense tumor blush
• resectability depends on angle between ICA and ECA
• patients often left with hoarseness due to proximity of vagus nerve
• preoperative embolization may be considered

3. Meningioma:

• highly vascular extra-axial neoplasm 
• core is supplied by branches of the ECA while periphery is supplied by the ICA
• "spoke wheel" appearance on angiogram
• resection is usually curative
• large tumors may be embolized prior to resection

REFERENCES

Pribram HFW. Selective catheterization of the external carotid artery. Radiology 1966;87:315-20.

Roberson GH, Price AC, Davis JM, et al. Therapeutic embolization of juvenile angiofibroma. AJR Am J Roentgenol 1979;133:657-63.

Wieneke JA, Smith A. Paraganglioma: carotid body tumor. Head Neck Pathol 2009;3(4)303-6.

Wilson G, Weidner W, Hanafee W. The demonstration and diagnosis of meningiomas by selective catheter angiography. AJR Am J Roentgenol 1965;95(4):868-73.

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.

Maffucci Syndrome

Maffucci Syndrome

• nonhereditary 
• enchondromatosis combined with hemangiomas
• enchondromas in Maffucci syndrome carry a relatively high risk of malignant transformation 
• chondrosarcoma is the most common musculoskeletal malignancy 
• high risk of developing non musculoskeletal malignancies
• ovarian, pancreatic, gastrointestinal adenocarcinoma, glioma

Imaging Findings

• expansile metaphyseal lesions 
• sclerotic margins
• chondroid mineralization with "ring and arc" pattern that is typical of cartilage containing lesions
• increased signal intensity on T2W MR due to high water content of hyaline cartilage

REFERENCES

Flach HZ, Ginai AZ, Oosterhuis JW. Maffucci syndrome: radiologic and pathologic findings. Radiographics 2001;21:1311-16.

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.