Caroli's Disease and Syndrome

Caroli's Disease

• autosomal recessive abnormality in ductal plate development
• communicating cavernous biliary ectasia 
• US will show:
• dilated intrahepatic bile ducts that are saccular or fusiform
• outpouchings may contain sludge/calculi due to biliary stasis 
• central dot sign - color Doppler shows flow in the portal triads surrounded by the dilated ducts
• ERCP/MRCP will show dilated ducts that communicate with the central biliary tree

Caroli's syndrome is Caroli's disease + congenital hepatic fibrosis.

REFERENCES

Levy AD, Rohrmann CA, Murakata LA, et al. Caroli's disease: radiologic spectrum with pathologic correlation. AJR Am J Roentgenol 2002;179:1053-7.

The Basion-Dens Interval

Injuries at the craniocervical junction are important to recognize due to their critical clinical implications. The basion-dens interval (BDI) is a parameter used to define the normal articulation between the occiput and the cervical spine. Measured on a midline sagittal image, the distance between the inferior tip of the basion and the tip of the dens is less than 12 mm in 95% of adults. A value greater than 12 mm is concerning for atlanto-occipital dislocation.  

The above image is from a patient with bilateral atlanto-occipital dislocation with anterior translation of the occiput relative to the cervical spine.


REFERENCES
Deliganis AV, Baxter AB, Hanson JA, et al. Radiologic spectrum of craniocervical distraction injuries. Radiographics 2000;20:S237-50.

Segmental Testicular Infarction

The presentation of an acute scrotum in the emergency setting typically leads to a work up for testicular torsion with ultrasound imaging. Accurate diagnosis of acute testicular torsion is important because the risk of global testicular infarction increases with time from onset of symptoms. 

Segmental testicular infarction is a rarer entity that is not well described in the literature. Ultrasound will demonstrate wedge shaped, hypoechoic regions in the testes with absence of vascular flow. The differential diagnosis for this finding is:

• polycythemia vera
• intimal hyperplasia of the spermatic artery
• sickle cell anemia
• vasculitis
• systemic lupus erythematosus
• polyarteritis nodosa
• venous thromboses (in hypercoagulable states)
• severe epididymo-orchitis that is unresponsive to treatment
• trauma

Differentiation between these entities and testicular torsion is important because treatment of the underlying condition (i.e. with steroids for polyarteritis nodosa) can prevent an unnecessary orchidectomy.


REFERENCES
Fernandez-Perez GC, Tardaguila FM, Velasco M, et al. Radiologic findings of segmental testicular infarction. AJR Am J Roentgenol 2005;1587-93.
Sriprasad S, Kooiman GG, Muir GH, et al. Acute segmental testicular infarction: differentiation from tumor using high frequency colour Doppler ultrasound. BJR 2001;74:965-7.

Mucocele of the Appendix

The above images are from a patient who presented to the emergency room with right lower quadrant pain and nausea. Acute appendicitis was suspected. CECT demonstrated a dilated, tubular, fluid filled structure arising from the cecal base. Its maximal diameter was 3 cm. No pericecal inflammatory changes were seen. The patient was taken to the operating room and found to have an appendiceal mucocele.

Mucocele of the appendix refers to a dilated, mucus-filled appendix. CECT findings depend on the histologic type of mucocele. Mucosal hyperplasia (simple mucocele) and mucinous cystadenoma (benign tumor) will appear as a well circumscribed cystic structure with water attenuation of its lumen. Peripheral calcifications are seen in approximately 50% of cases. Mucinous cystadenocarcinoma (malignant tumor with higher risk of perforation) appears as a large, irregular mass with nodular mural thickening, solid and cystic components, and calcifications.

Clinically, the presentation of appendiceal mucocele is identical to that of acute appendicitis. However, pre-operative diagnosis of the former is important since it changes the surgical management - rupture of a mucocele can cause free spillage of mucus into the peritoneal cavity resulting in pseudomyxoma peritonei. Discovery of a neoplastic cause for appendiceal mucocele usually warrants a right hemicolectomy.


REFERENCES
Bennett GL, Tanpitukpongse TP, Macari M, et al. CT diagnosis of mucocele of the appendix in patients with acute appendicitis. AJR Am J Roentgenol 2009;192(3):W103-10.
Pickhardt PJ, Levy AD, Rohrmann CA, et al. Primary neoplasms of the appendix manifesting as acute appendicitis: CT findings with pathologic comparison. Radiology 2002;224:775-81.

Cystic and Solid Lesions of the Cardiophrenic Space

The cardiophrenic space is located at the base of the mediastinum and is defined by the base of the heart, the diaphragm, and the chest wall. Normally, this space is occupied by fat although both benign and malignant lesions can be found in this location.

Cystic Lesions

1. Pericardial cysts
• benign
• usually in the right cardiophrenic space
• CT: well defined, smooth-walled cyst filled with simple fluid
• MR: high signal intensity on T2WI
2. Hydatid cyst
• rare
• may be a herniated hepatic hydatid cyst
• CT: uni- or multilocular cyst with peripheral mural calcifications
• MR: mother cyst (the matrix) is usually intermediate signal intensity on T1WI; daughter cysts are high signal intensity on T2WI
3. Thymic tumors with cystic components

Solid Lesions

1. Lymphadenopathy
• > 8mm in short axis diameter is considered pathologic
• lymphoma is most common cause
2. Thymoma

REFERENCES

Pineda V, Andreu J, Caceres J, et al. Lesions of the cardiophrenic space: findings at cross-sectional imaging. Radiographics 2007;27:19-32.

Extracapsular Rupture of Breast Implants

The above images are from a woman who presented with left chest wall pain after a motor vehicle accident. CECT demonstrates bilateral prepectoral breast implants with asymmetry in size, retraction of the left implant, thickening of its capsule and surrounding hematoma. Findings are suspicious for extracapsular rupture.

While most centers use CECT for the initial evaluation of trauma patients, MRI with dedicated breast coil is the most sensitive for detecting implant rupture. Findings on various imaging modalities include:

Mammography: 

• wrinkled contour of implant
• dense, globular masses due to extracapsular silicone

Ultrasound:

• stepladder sign - linear echogenic layers of the collapsed implant shell
• "snowstorm" appearance - increased echogenicity due to extracapsular spread of silicone

MRI:

• T2WI may show extracapsular high signal
• use of water suppressed STIR images will render bright signal for silicone

REFERENCES

Brown SL, Middleton MS, Berg WA, et al. Prevalence of rupture of silicone gel breast implants revealed on MR imaging in a population of women in Birmingham, Alabama. Am J Roentgenol 2000;175:1057-64.

Scaranelo AM, Marques AF, Smialowski EB, et al. Evaluation of the rupture of silicone breast implants by mammography, ultrasonography and magnetic resonance imaging in asymptomatic patients: correlation with surgical findings. Sao Paulo Med J 2004;122(2):41-7.

Pepper Pot Skull

Pepper pot skull (or salt and pepper skull) refers to a granular, mottled appearance of the calvarium with tiny hyperlucent areas. Other descriptive terms for this finding include ground glass texture and loss of differentiation between the inner and outer tables of the skull. This appearance is attributed to the resorption of trabecular bone and is seen in hyperparathyroidism. While some may use the term pepper pot skull to describe the lytic skull lesions seen in multiple myeloma, these lesions typically produce larger hyperlucent areas in the calvarium and are often referred to as "punched out" lucencies.

I recommend taking a look at the reference below - a cute reminder of all of the "food signs" in radiology.

REFERENCES
Roche CJ, O'Keeffe DP, Lee WK, et al. Selections from the buffet of food signs in radiology. Radiographics 2002;22:1369-84.