MRI of polysplenia syndrome.

The polysplenia syndrome is the association of multiple spleens, situs inversus, congenital heart disease, and azygous continuation of the inferior vena cava. Magnetic resonance (MR) is a noninvasive imaging modality which can easily confirm the multiplicity of spleens, situs inversus, and identify complex congenital cardiovascular malformations. The anomalies of the polysplenia syndrome as imaged by MR are presented.

Masked obstruction of the renal collecting system.

Two cases of apparent unilateral renal obstruction in which lesser contralateral obstructions were not seen are presented. In both cases, relief of the more severe obstruction resulted in an unmasking of the milder contralateral lesion.

Mammographic and CT detection of extrathoracic lung herniation.

Herniation of lung through the chest wall is uncommon and previously reported cases have been found either clinically or by chest radiography. We recently discovered a case of herniated lung on screening xeromammography. These findings were correlated with thoracic CT.

The variable anteroposterior position of the retroperitoneal colon to the kidneys.

Five hundred supine abdominal CT scans were reviewed retrospectively to determine the variation of colonic position about each kidney. The anteroposterior position of the retroperitoneal colon was evaluated for different age groups and sexes at the level of the upper-, mid-, and lower-renal poles. The ascending/descending colon generally assumed a more posterior position about the lower poles and left kidney vs. the upper poles and right kidney. There were few significant differences between the sexes and among different age groups with two exceptions. In middle-aged and older women, the descending colon lay more lateral to the left lower kidney than in their male counterparts. Second, although the colon was located behind the kidney (retrorenal colon), in a nearly equal number of men and women, most patients with this colonic position were 60 years of age or older and had it about their lower renal poles. The overall frequency of retrorenal colon in the supine patient was 1.9%.

The retrorenal colon in the supine and prone patient.

Ninety patients underwent computed tomographic scanning in both the supine and prone positions to show the orientation of the retroperitoneal colon about the kidneys and allow evaluation of changes in colonic position and contents. The data were compared with data on 500 patients scanned only when supine. Particular attention was given to bowel found posterior to the kidneys (retrorenal colon): its frequency of occurrence on 500 scans of supine patients was 1.9%, but 10.0% in the 90 prone patients. Because most invasive renal procedures would not intersect with retrorenal colon located behind the lateral one-third of the kidney, the data were reevaluated after deletion of these patients, giving a frequency in prone patients of 4.7%. This was found exclusively at the level of the lower renal poles, and the involved colon was extensively distended with gas. Attention should be given at fluoroscopy to detect this unusual, posteriorly positioned, air-filled colon before any invasive renal procedure.

Differential diagnosis of prolonged cortical retention of radiotracer in technetium-99m DTPA renal scintigraphy.

The mechanisms of prolonged renal cortical tracer retention in Tc-99m DTPA scintigraphy are discussed and a variety of examples are presented.

Radionuclide demonstration of a renopleural fistula following trauma.

A renopleural fistula was detected on a Tc-99m DTPA renal study during evaluation for possible post-traumatic urinoma.

Poland-Möbius syndrome: evaluation by computerized tomography.

The Poland-Möbius syndrome is the combination of two rare congenital disorders and has been reported previously in only 13 patients. We report two additional cases with an evaluation of the findings and possible pathogenesis, and discuss the role of computerized tomography in evaluating the brain, pons, orbits, and facial nerve.

Glomerular filtration rate determined in conjunction with routine renal scanning.

A method has been developed to estimate glomerular filtration rate using computer evaluation of images obtained during routine renal scanning. The technique requires less than 40 minutes of imaging time, requires only a single blood sample, and correlates highly with 24 hour creatinine clearance.

Gas washout and pressure waveform characteristics of high-frequency oscillation.

High-frequency oscillation (HFO) minimizes tidal volume. To investigate whether ventilation can proceed when tidal movement (volume) is eliminated, a nondistensible physical model of interconnected chambers was constructed. During HFO, ventilation was related to pressure waveform characteristics recorded within the separate chambers. Ventilation increased up to a critical frequency related to the time constant of the system. Beyond this frequency, ventilation dropped off rapidly.