ESWL-induced Perinephric Hematoma

Ultrasound image of the kidney shows a crescentic heterogeneous hypoechoic lesion in the perinephric space (arrows). The kidney is marked by the calipers. 

Axial unenhanced CT images confirm a thick left perinephric hematoma (stars) and several fragmented stones in the lower pole of the left kidney.

Facts

• ESWL (Extracorporeal Shock Wave Lithotrypsy) is a common and standard treatment for renal/proximal ureteric calculi in majority of patients
• Most common complication = microscopic hematuria
• Perinephric hematoma and infection (including pyelonephritis) can occur
• Incidence of hematoma varies depending on method of diagnosis. By US, incidence is about 0.1-0.6%. By CT/MRI, incidence rises to 20-25% of cases. 
• No clear correlation between number of shockwaves or intensity given and incidence of hematoma
• Most perinephric hematoma resolves spontaneously within 2 years and the renal function is preserved. They are mostly treated conservatively

Imaging: US and CT

• Crescent-shaped collection surrounding the affected kidney
• Hypoechoic on US, hyperattenuating on non-contrast CT and no enhancement after IV contrast
• Displacement or compression of adjacent renal parenchyma
• Differentiate from subcapsular hematoma by appearance and pressure effect to underlying kidney.
• "Page" kidney occurs when (usually) subcapsular hematoma causes chronic renal parenchymal compromise and then hypertension

Reference:
Labanaris AP, Kuhn R, Schott GE, Zugor V. Perirenal hematomas induced by extracorporeal shock wave lithotripsy (ESWL). Therapeutic management. TheScientificWorldJOURNAL 2007;7:1563-1566.

Mediastinal Neuroblastoma

Axial CT image at the level of mid thoracic spine of a 5-year-old boy shows a well-circumscribed, enhancing left paraspinal mass located between the medial ends of the ribs. 

An MIBG study (posterior view of the thorax and upper abdomen) shows a focus of moderate uptake in the left side of the lower thorax, corresponding with the site of abnormal mass on CT. Note intense uptake of bilateral adrenal glands. 

Facts: Neuroblastoma

• 8-10% of all childhood malignancies
• Malignant tumor composed of immature ganglion cells. Most (2/3) arise from abdomen or pelvis and the rest is extra abdominal
• Typically seen in children under age of 5 years
• Treatment determined by stage of tumor at presentation. Regionally limited disease is potentially resectable, but locally extensive or disseminated disease is usually not resectable
• Current imaging staging evaluation: 1) CT or MRI of primary tumor, 2) skeletal survey, 3) bone scintigraphy or MIBG for bone metastasis, and 4) bone marrow aspiration and biopsy for marrow disease
• CT alone has low sensitivity (43%) but high specificity (97%) for detection of stage 4 disease. CT accuracy = 81%. MRI is more sensitive (83%) but less specific (88%) and slightly more accurate (85%). 

Imaging Findings: CT/MRI

• Sharply marginated, fusiform paraspinal mass
• Oriented along direction of sympathetic chain
• 40% contain calcifications
• Heterogeneous enhancement
• Differentiation from ganglioneuroblastoma (usually 5-10 years old) and ganglioneuroma (usually > 10 years old) not possible by imaging. Basically, they are tumors of sympathetic ganglia

References
1. Siegel MJ. Pediatric Body CT. 2008
2. Siegel MJ, Ishwaran H, Fletcher BD, et al. Staging of neuroblastoma at imaging: report of the radiology diagnostic oncology group. Radiology 2002;223:168-175. 

Avian Spur

Facts:

• AKA supracondylar process of the humerus
• Congenital osseous/cartilagenous projection arising from the anteromedial surface of the distal humerus
• Found in 1% of population
• Associated with ligament of Struthers, which connects the process to the medial epicondyle (fibers of pronator teres may arise from this structure)
• Median nerve and brachial artery pass below this arch and may be compressed
• Fracture is possible but rare

Reference:

Egol KA, Koval KJ, Zuckerman JD. Handbook of fractures; 4th ed, 2010. 

Superficial Femoral Vein: Misleading Medical Nomenclature

Anatomy and Definition of Superficial Femoral Vein (SFV)

• SFV, as understood by vascular surgeons and radiologists, is a continuation of the popliteal vein. After joining the deep femoral vein, it becomes common femoral vein
• Superficial femoral vein is actually a "deep" vein

The Problem

• Most vascular surgeons and radiologists understand that SFV is a deep vein, but many physicians in other specialty or general practitioners do not
• Based on a survey of multispecialty groups, only 24% of physicians would give anticoagulants to patients having "acute thrombosis of the superficial femoral vein". There is a misperception of many physicians that SFV is superficial vein, therefore it would not be treated as deep vein thrombosis

Recommendations: Don't Use "Superficial Femoral Vein". Use "Femoral Vein"

• Current consensus developed by experts in phlebology officially established “femoral vein” as the vein that originates from the popliteal vein and courses in the femoral canal and bluntly discarded “superficial femoral vein” as an “unauthorized term" … because it is a deep vein 
• SFV is not in the official Terminologica Anatomica
• The other vein is "deep femoral vein" or "profunda femoris vein"
• Supported by International Interdisciplinary Consensus Committee on Venous Anatomical Terminology convened on September 8–9, 2001 (Nomenclature of the veins of the lower limbs: an international interdisciplinary consensus statement. J Vasc Surg 2002; 36:416-422)
•  Supported by Society of Interventional Radiology

Reference:
Hammond I. The superficial femoral vein. Radiology 2003;229;604-666 (link)