MDCT of Active Extravasation

An axial CT image shows a laceration of the spleen (arrowhead), hemoperitoneum and localized area of high attenuation (arrow) in the perisplenic space, which had faced away on subsequent delayed images indicating active extravasation.

Facts:

• Area of hyperattenuation (mostly greater than 100 HU) within a hematoma on initial images that fades into an enlarged, enhanced hematoma on delayed images
• Active extravasation is an uncommon but important finding in trauma patients
• Indicates significant bleeding that may require surgical or endovascular treatment

Differential Diagnosis of High-Attenuation Area Within a Hematoma in Trauma Patients

• Active extravasation
• Pseudoaneurysm: adjacent to a vessel, no enlargement or increased attenuation on delayed images
• Bone fragment: no change on delayed images
• Foreign body

Reference:

Hamilton JD, Kumaravel M, Censullo ML, et al. Multidetector CT evaluation of active extravasation in blunt abdominal and pelvic trauma patients. Radiographics 2008; 28:1603-1616.

Rolando Fracture

PA radiograph of the thumb demonstrates an intra-articular fracture of the base of the metacarpal with mild displacement.

Facts: Rolando Fracture

• Originally described by Dr. Rolando as Y-shaped intraarticular fracture that extends to the carpometacarpal joint surface
• Now, the eponym is widely used for any comminuted intraarticular fracture at the base of the thumb
• Secondary to axial loading crusing the articular surface of the first metacarpal
• Usually require operative reduction because of high association with post-traumatic arthritis if incongruity present at the articular surface

Reference:

Peterson JJ, Bancroft LW. Injuries of the fingers and thumb in the athlete. Clin Sports Med 2006; 25:527-542.

Small Arterially Enhancing Hepatic Lesion in Cirrhotic Patients

Axial T1WI post contrast images in arterial and portovenous phase demonstrates a tiny enhancing nodule in hepatic segment V, which becomes isosignal to the liver on the portovenous phase. This nodule is occult on unenhanced T1WI and T2WI.

Hepatic Arterial Phase Detection of Small HCC

• Hepatic arterial phase imaging very important to detect small HCCs, which may be occult with other pulse sequences, at unenhanced or portovenous phase MR imaging
• Most HCCs demonstrate arterial enhancement and moderate T2 hyperintensity
• Some small HCCs, however, are seen only during the hepatic arterial phase

Differential Diagnosis of Small Arterially Enhancing Lesion in Cirrhotic Liver

• Hepatocellular carcinoma
• High-grade dysplastic nodule
• Focal nodular hyperplasia (FNH)
• Hemangioma
• Pseudolesions: arterial-portal venous shunt, aberrant venous drainage

Hepatic Pseudolesions

• Arterial enhancement but occult on portovenous and/or equilibrium phases, and at unenhanced T1- and T2-weighted MR imaging
• A retrospective study of 16 patients with 45 lesions showed that the majority (93%) of them were benign without any correlative pathologic findings. The remaining 7% that lesions were HCC, did have other concomitant HCC.
• It seems reasonable to follow these lesions closely with imaging to ensure they do not grow (if they grow, they are likely to represent HCC)

Our case - hepatic pseudolesion, the nodule has disappeared on follow-up MRI performed 3 months later.

Reference:

Holland AE, Hecht EM, Hahn WY, et al. Importance of small (equal or less than 20 mm) enhancing lesions seen only during the hepatic arterial phase at MR imaging of the cirrhotic liver: evaluation and comparison with whole explanted liver. Radiology 2005; 237:938-944.

Soft Tissue Evaluation on Wrist Radiography

Two images demonstrate five fat planes on the PA wrist radiograph, and four fat planes on the lateral wrist radiograph that should be scrutinized on any wrist radiography interpretation.

Facts:

• Soft tissue swelling is almost always seen in one or more compartments in cases of acute fracture or dislocation
• When swelling is observed on a trauma wrist radiograph, all soft tissue areas should be examined thoroughly and the assumption is that they may be a fracture or dislocation associated with swelling
• Abnormal fat planes = fat plane is convex out of the underlying bone, or loss of its distinct plane

What Do They Suggest?

• Dorsal hand swelling -> 2nd through 5th metacarpal injury
• Dorsal wrist swelling -> carpal fractures or wrist dislocation
• Dorsal radial swelling -> forearm fractures
• Pronator fat pad swelling -> forearm fractures
• Thenar swelling -> thumb fractures
• Hypothenar swelling -> 2nd through 5th metacarpal injury
• Scaphoid swelling -> carpal fractures
• Pararadial swelling -> forearm injury
• Paraulnar swelling -> forearm fracture

Reference:

Curtis DJ, Downey, Jr., EF, Brower AC, et al. Importance of soft-tissue evaluation in hand and wrist trauma: statistical evaluation. AJR 1984; 142:781-788.

Bladder Stones

Transverse ultrasound image of the urinary bladder shows a 5-cm mobile hyperechoic lesion (between arrows) with posterior acoustic shadowing within the bladder lumen.

Facts:

• Risk factors: urinary stasis (voiding dysfunction i.e., urethral stricture, benign prostatic hyperplasia, bladder neck contracture, neurogenic bladder), infection, bladder diverticula, foreign body (Foley catheter balloon, suture material, etc)
• Common compositions: uric acid, ammonium urate, calcium oxalate
• Uric acid stones predominate in a setting of bladder outlet obstruction
• Magnesium ammonium phosphate and apatite stones predominate in a setting of urinary tract infection (UTI)
• Patient presentation: hematuria, suprapubic pain, interruption of urine stream

Imaging

• If sufficiently calcified, bladder stones may be visible on radiography
• Tends to locate in the midline when the patient is supine
• If calcification is located laterally, think of a stone in the diverticulum or ureterocele
• Key to confirm that the abnormality is a stone = mobility (either on radiography or ultrasound)

Reference:

1. Zagoria RJ. Genitourinary Radiology: the Requisites, 2004.

2. Tanagho EA, McAninch JW. Smith's General Urology, 2004.