The value of MR in differentiating subligamentous from supraligamentous lumbar disk herniations.

PURPOSE: To determine the value of MR criteria in differentiating subligamentous from supraligamentous lumbar disk herniations. METHODS: A retrospective review of surgical reports and MR images of 50 patients undergoing first-time lumbar surgery was performed. Three MR imaging criteria were assessed: the presence and integrity of a low-signal-intensity line posterior to the disk herniation, the size of the disk herniation in comparison with the size of the spinal canal, and the presence of disk fragments. Correlation was made with surgical findings to determine the value of these MR criteria in differentiating subligamentous from supraligamentous disk herniations. RESULTS: For determining subligamentous disk herniations: the presence of a continuous low-signal-intensity line posterior to the disk herniation was 29% sensitive, 65% specific, and 42% accurate; disk herniation size less than 50% of the size of the spinal canal was 64% sensitive, 47% specific, and 58% accurate; and the absence of disk fragments was 88% sensitive, 12% specific, and 62% accurate. Combinations of individual MR criteria did not improve diagnostic accuracy. CONCLUSIONS: For differentiating subligamentous from supraligamentous lumbar disk herniations, none of the MR imaging criteria assessed was reliable.

MRI of intracranial subependymomas.

OBJECTIVE: We report imaging features of two cases of subependymoma, a relatively rare benign intraventricular neoplasm. MATERIALS AND METHODS: The first case was a lateral ventricular tumor, which grew to a large size before becoming symptomatic. The second case was a fourth ventricular subependymoma with extensive cisternal spread. RESULTS: In Case 1, absence of postcontrast enhancement suggested the correct diagnosis. However, in Case 2 heterogeneous enhancement made the diagnosis uncertain. In both cases, pre- and postoperative MRI was superior to other modalities in defining tumor extent and delineating the surrounding anatomy. CONCLUSIONS: Magnetic resonance imaging is the modality of choice for studying subependymomas. The diagnosis should be placed among differential considerations for intraventricular tumors.

Computed tomography in pulmonary tuberous sclerosis.

Pulmonary disease is a rare manifestation of tuberous sclerosis. Respiratory symptoms often progress to severe pulmonary insufficiency and death may ensue within a few years of diagnosis. We describe a case where a computerized tomographic scan aided early diagnosis in a patient with spontaneous pneumothorax and subtle, nonspecific changes on a plain x-ray film.

Developing spinal column: gadolinium-enhanced MR imaging.

Enhancement characteristics of the normally developing spinal column were examined in magnetic resonance (MR) images obtained in 58 children aged 7 days to 9 years. With a 1.5-T imager, short-repetition-time spin-echo images were obtained before and after the administration of 0.1 mmol/kg gadopentetate dimeglumine. Enhancement of normal bone marrow was seen in all patients aged less than 7 years; it was marked only in patients aged less than 2 years. Enhancement of normal cartilage, seen in all patients aged less than 1 1/2 years, may be the most striking feature of enhanced MR images of the infant spine. Enhancement of both bone marrow and cartilage in children appears to be due to the unusual prominence of vasculature, associated with permeability of the capillary endothelium and a plentiful extravascular space. Although marked and diffuse enhancement of vertebral bodies in adults is often thought to indicate a pathologic marrow state, caution must be used before the same criteria are applied to children.

Transjugular liver biopsy in high-risk patients with hepatic disease.

Records were reviewed of 160 patients who underwent transjugular liver biopsy (TJLB) during a five-year period. Percutaneous transperitoneal needle biopsy was contraindicated in 95% of these patients because of coagulation abnormalities or massive ascites. Moderate complications occurred in two patients. Diagnostic biopsy material was obtained in 129 (81%). TJLB provided useful information in 44 of 58 patients without documented alcohol abuse (clinical Groups III and IV). TJLB disclosed additional diagnoses aside from Laennec cirrhosis in 15 of 48 alcoholic patients with sudden clinical deterioration (Group II), including 11 cases with other stages of alcholic liver disease and four cases of primary or metastatic neoplasm. TJLB revealed diagnoses other than Laennec cirrhosis, including three neoplasms, in six of 54 clinically stable alcoholics (Group I). TJLB frequently yielded important data relative to clinical management or prognosis in Group II, III, and IV patients; it was less useful in Group I patients.

Role of selective venous catheterization of the small thyroid veins as a diagnostic study in hypercalcemic states.

Previous studies of selective venous catheterization stress its value in localizing hyperfunctioning parathyroid tissue in patients with an established diagnosis of hyperparathyroidism. Our study presents our experience with selective venous catheterization as a diagnostic aid in differential diagnosis of hypercalcemia. In our four patients, an extensive metabolic work-up did not resolve the differential diagnosis of hypercalcemia, and selective venous catheterization provided the ultimate data that led to the correct diagnosis of hypercalcemia in each patient. Selective venous catheterization can be an important diagnostic study in carefully selected patients with hypercalcemia.

The transjugular route as an alternative to direct percutaneous needle biopsy of the liver.

Transjugular liver biopsy was attempted in 32 cases of hepatocellular dysfunction with hemocoagulation disorders, ascites or marked obesity. A catheter was inserted in the right internal jugular vein and advanced into a hepatic vein under fluoroscopic control. A long needle was passed through the catheter and into the liver parenchyma for the biopsy. Diagnostic specimens were obtained in 28 instances (88%). The procedure was always well tolerated and no complications occurred. The transjugular approach offers a safe, practical alternative for liver biopsy in cases where direct percutaneous puncture is contraindicated.