Tailored CT: primum non nocere.

Despite its vital diagnostic utility, the ionizing radiation used in CT is not benign. Patients have an increased risk of dying from a radiation-induced cancer for every pass through a CT scanner. One way to reduce this risk is to tailor CT, especially follow-up scans, to specific areas of concern. By doing so, we can help to minimize the small but real risk from this essential technology.

Differential density of normal renal parenchyma on nonenhanced CT: a new observation.

PURPOSE: Nonenhanced CT scans through the kidneys commonly show a difference in radiopacity between the inner peripelvic portion of the renal parenchyma and the more peripheral regions of the renal parenchyma. This normal observation has not been described. METHOD: We reviewed 50 nonenhanced CT scans. Renal parenchyma was evaluated by both visual inspection and density measurements of inner and outer aspects of the kidneys in 38 and visual inspection only in 12. A narrower window was used to better show density differences (100 W, 35 L). We recorded the indication for the CT, history, and recent blood chemistries. RESULTS: The inner parenchyma was of greater radiopacity than the outer parenchyma in 35 of 50 cases by visual inspection and in all densitometry cases (38 of 38). There was no correlation with clinical history or blood chemistry. CONCLUSION: A difference in density between the inner and outer portions of the renal parenchyma is very common and will often be seen if one looks for it. We have not shown an etiology for this difference, and indeed, it may be physiological. One must be aware of this finding to avoid mistaking it for pathology.

Testicular feminization: radiologic considerations in a unique form of cryptorchidism.

A case report of complete testicular feminization is presented. The medical and radiological characteristics of this condition which distinguish it from male cryptorchidism and other disorders of sexual differentiation are discussed. To our knowledge, only three previous case reports have been published in the radiology literature. Our report is the first to describe MRI findings.

Case report: intermittent sciatic herniation of the ureter.

Sciatic herniation is the rarest form of pelvic hernia. Herniation of the ureter into the sciatic foramen is extremely uncommon with only 11 cases reported in the literature. We describe an unusual case of intermittent herniation of the ureter during an intravenous urogram.

A survey of radiology clerkships at teaching hospitals in the United States.

RATIONALE AND OBJECTIVES: The nature and extent of medical school radiology clerkships were qualified. METHODS: Questionnaires were sent to 126 medical school radiology departments in the United States. Queries were made regarding length and requirements for clerkships, methods of teaching, methods of student evaluation, and responsibility for these functions. RESULTS: Fifty-seven responses (45%) were received. Methods of student teaching varied, but most departments relied on readout sessions, watching procedures, "show-and-tell" sessions, didactic slide and film presentations, and various other methods. Emphasis of most student clerkships was placed on teaching imaging disease processes rather than on how to read x-rays. A written examination was most commonly used to evaluate student performance. Most teaching was done by full-time faculty, with lesser contributions from part-time faculty, fellows, and residents. CONCLUSIONS: The nature and extent of medical school radiology clerkships in departments responding to the survey varied, but most conformed, at least in part, to standards based on survey results and the published literature.

Loculated mediastinal chylothorax resulting from esophagogastrectomy: a case report.

The thoracic duct is closely related to the esophagus and the pleura. During an esophagogastrectomy, the thoracic duct is at risk for injury, which usually results in chylous pleural effusions. We present an uncommon situation, however, where the pleura was not violated and a large mediastinal lymph collection resulted.

Radiocontrast-associated renal dysfunction: incidence and risk factors.

Contrast-induced nephropathy is a potentially serious untoward reaction to radiologic contrast media. The incidence of this nephropathy and the predisposing conditions are not well established, possibly because of methodologic differences between studies. We evaluated the incidence of contrast-induced nephropathy after femoral arteriography in 394 patients by using multiple definitions (different increases in serum creatinine or blood urea nitrogen levels at various times). When an increase in the level of serum creatinine of greater than 0.3 mg/dl and greater than 20% on day 1, 2, or 3 and on day 5, 6, or 7 was used to define the disorder, the incidence in our group of patients was 10% for nonazotemic patients vs 30% for azotemic patients (p less than .001); 2% for nondiabetic, nonazotemic patients vs 16% for diabetic, nonazotemic patients (p = .003); and 38% for patients who were both diabetic and azotemic vs 16% for diabetic, nonazotemic patients (p = .022). Baseline renal insufficiency and diabetes mellitus (especially when insulin dependent) were significant predisposing factors. The effects of dehydration and increased volume of contrast medium on the incidence of contrast-induced nephropathy were not clear; the age and sex of the patient were not important risk factors. The incidence of contrast-induced nephropathy depends on the definition used. Although contrast-induced nephropathy may develop in any patient, diabetes, renal insufficiency, and, possibly, dehydration and dose of contrast medium are risk factors.

Radiocontrast-associated renal dysfunction: a comparison of lower-osmolality and conventional high-osmolality contrast media.

Nephropathy is an established untoward event associated with intravascular administration of conventional high-osmolality contrast media (HOM). It has not been shown previously that lower-osmolality contrast media (LOM) are less nephrotoxic in a clinical setting. We evaluate the ability to replace HOM with LOM (in lower-extremity angiography) to reduce the incidence of nephropathy. We use multiple definitions for contrast-induced nephropathy (six different magnitudes of rise of serum levels of creatinine or blood urea nitrogen in various periods). The incidences of nephrotoxic effects with LOM vs HOM in patients with presumed risk factors, including preexisting renal insufficiency and diabetes, are evaluated also. When all patients are considered, the incidence of contrast-induced nephropathy for LOM vs HOM (defined as an increase in serum creatinine level greater than 0.3 mg/dl and greater than 20% on day 1, 2, or 3 and on day 5, 6, or 7, is 7% vs 26% (p = .001). When only patients with preangiography azotemia are considered, the incidence of contrast-induced nephropathy for LOM vs HOM is 10% vs 41% (p = .017); for diabetic patients, regardless of preangiography creatinine level, the incidence is 10% vs 31% (p = .012). Although contrast-induced nephropathy may develop even in a patient with no risk factors who receives LOM, LOM is associated with a decreased incidence of this condition, to various degrees, depending on the presence of risk factors.

Excessive accumulation of normal retroperitoneal fat mimicking a neoplasm: urographic/CT correlations.

Computed tomography (CT) was performed on four patients in whom excretory urograms revealed marked displacement of the kidneys and/or ureters. CT in each case was remarkable for the presence of excessive accumulation of normal retroperitoneal fat and failed to document the existence of a retroperitoneal neoplasm, lymphadenopathy, or other pathological mass.

CT diagnosis of circumcaval ureter.

Variability in the normal course of the ureter makes it difficult to differentiate a normal variant from a congenital anomaly or deviation caused by a mass. CT can be useful in making this distinction. We present five cases of circumcaval ureter in which contrast-enhanced CT, by showing the ureter passing posterior and medial to the inferior vena cava (IVC), provided the definitive diagnosis. In addition, we studied the position of the inferior vena cava in the midlumbar region in 100 consecutive contrast-enhanced CT scans and compared the results with the position of the IVC in our five cases of circumcaval ureter plus one case of circumcaval ureter taken from the literature. Whereas only 6% of the normal patients had an IVC lateral to the right pedicle of the third lumbar vertebra, all of the patients with a circumcaval ureter and the one case in the literature had the IVC lateral to the pedicle. Therefore, the finding of a laterally placed IVC on CT is suggestive but not pathognomonic of circumcaval ureter. Contrast-enhanced CT can be used to prove the diagnosis of circumcaval ureter, and lateral placement of the IVC on non-contrast-enhanced CT suggests the diagnosis.

Hyperbaric therapy for the removal of an obstructing intestinal tube balloon.

Gaseous distention of the mercury bag of intestinal long tubes has been known to result in small bowel obstruction. In the case presented, hyperbaric therapy was used to reduce the size of the impacted balloon and facilitate its removal. Hyperbaric therapy provides a safe, effective alternative to more invasive methods of balloon removal.

Renal oncocytoma: new observations.

Renal oncocytomas are uncommon, benign tumors that can be treated by local excision or heminephrectomy; their preoperative differentiation from renal cell carcinoma, treated by radical nephrectomy, would be invaluable. A particularly important finding, a central scar--not stressed in previous reports, is frequently demonstrated by CT examination. We evaluated radiographic studies of 18 pathologically confirmed cases of oncocytoma and compared findings with results of CT, sonography, and angiography studies of 18 renal cell carcinoma cases. Oncocytomas can be suggested if a stellate scar is identified within an otherwise homogenous tumor on ultrasound (US) and CT; if the mass appears homogeneous but no scar is present, angiography should be performed. An oncocytoma can be suggested in these cases if a spoke-wheel configuration and homogeneous blush are present. These criteria, which are reliable only if the mass is 3 cm or larger, would have resulted in the correct diagnosis of oncocytoma in 16/18 cases.