Obturator mononeuropathy caused by pelvic cancer: six cases.

OBJECTIVE: To report the clinical and pelvic CT findings in six patients with obturator mononeuropathy caused by cancer. DESIGN: A clinical case series of six patients followed for 2 months to 10 years (one patient lost to follow-up). SETTING: Three referral centers. PATIENTS: Three men and three women, ages 52 to 81 years. Three patients had transitional cell carcinoma of the bladder, and one patient each had pelvic papillary carcinoma, carcinoma of unknown origin, and lymphoma. MAIN RESULTS: In each patient, symptoms of obturator mononeuropathy were the sole presenting sign of new or recurrent pelvic cancer. Three patients had ipsilateral leg edema in addition to the typical sensory and motor findings of obturator mononeuropathy. Tumor sites detected on pelvic CT that correlated with obturator nerve compression or infiltration, singly or in combination, included the posterolateral wall of the upper pelvis or midpelvis, the anterior wall of the lower pelvis, and the external obturator and pectineus muscles extrinsic to the bony pelvis. Antineoplastic treatment provided symptomatic relief in four patients. CONCLUSIONS: Pelvic CT or MRI should be performed to exclude pelvic tumor in patients with obturator mononeuropathy if there is no temporal association with pelvic trauma or intra-abdominal, pelvic, or hip surgery.

Comparison of iohexol-240 versus iohexol-300 in abdominal CT.

Forty patients without evidence of liver, kidney, or significant cardiac disease were prospectively divided into two groups of 20, receiving either iohexol-240 or iohexol-300. A contrast load of 150 ml was administered in conjunction with a rapid scanning technique at a preselected, fixed level to include liver, renal cortex, and aorta. Peak enhancement was calculated as change in Hounsfield units (HU) over baseline for each area of interest. Mean peak enhancement and standard deviation were calculated for each organ, and the difference between the means for the two contrast agents was compared using the Student's t test. Differences were not statistically significant with all p values greater than 0.05. Our results suggest iohexol-240 is preferred to iohexol-300 for body computed tomography (CT) due to its lower cost and iodine load without statistically significant change in diagnostic quality of the examination.

Doppler color imaging. Scrotum, breast, thyroid, and extremities.

DCI, when coupled with small-parts gray-scale imaging, has demonstrated great utility in the evaluation of superficial body abnormalities. This technique has rapidly become a primary method of evaluation of suspected testicular torsion, and its results are competitive with those of standard nuclear medicine examinations. DCI evaluation of male impotence, coupled with intracavernous injection of vasoactive substances, is now a leading, noninvasive technique for diagnosis of both arteriogenic and venogenic causes. DCI may provide invaluable information in the evaluation of palpable masses, particularly in the diagnosis of vascular abnormalities such as false aneurysm and arteriovenous fistula. Further studies are needed to corroborate the utility of DCI in the evaluation of focal thyroid and parathyroid abnormalities, breast carcinoma, nodal cancer, and the orbit. Because this technique is applicable to superficial, high-frequency examinations, DCI is rapidly becoming an accepted and frequently necessary part of any small-parts ultrasound study.

Magnetic resonance. Principles and applications.

Magnetic resonance is a unique, noninvasive imaging modality which allows direct, multiplanar imaging and the possibility of obtaining biochemical information in vivo. Presently, MR appears most applicable to the evaluation of central nervous system abnormalities. The high sensitivity of MR in the evaluation of intracranial pathology suggests that it may eventually replace CT for many suspected diseases, if future investigations are able to improve its specificity. As previously noted, MR may be more diagnostic than other radiologic studies in the evaluation of suspected Chiari malformation, syringomyelia, congenital abnormalities, tumors of the spinal axis, and disc space infection. In the chest, MR appears to be more accurate than CT in the determination of the extent of mediastinal tumor, but at present cannot replace CT because of the lack of experience in imaging parenchymal nodules and benign diseases. MR of the breast is promising, but the size of the lesion may prove to be a limiting factor with magnetic field strengths commonly being utilized. There are inherent difficulties in the evaluation of cardiac disease with MR, but it offers a noninvasive method of investigating congenital heart disease and may provide valuable information in suspected myocardial ischemia and altered cardiac function. MR provides a new method of evaluating the vascular system, both in terms of providing anatomic information on large and medium-sized vessels and flow analysis. In the abdomen, MR appears to be most sensitive in the evaluation of suspected hepatic masses, but as with the brain, greater specificity will be needed to replace CT. At the present time, MR offers no distinct advantage over conventional imaging modalities in the evaluation of pancreatic disease, it maybe more accurate than CT in the staging of renal cell carcinoma. Larger studies are needed to determine the role of MR in the investigation of retroperitoneal adenopathy and adrenal abnormalities. In the pelvis, MR offers the hope of earlier diagnosis of prostatic carcinoma and may replace CT for staging of prostatic carcinoma and transitional cell carcinoma of the bladder. Limited MR experience with benign disease of the female pelvis suggests that it is currently more accurately evaluated with ultrasound. MR appears to be highly sensitive and specific for the diagnosis of avascular necrosis and may provide an early clue in suspected osteomyelitis. Finally, in vivo MR spectroscopy may provide unique metabolic information that was unobtainable prior to the advent of magnetic resonance, if this proves to be technically feasible.

Improved technique for CT-guided celiac ganglia block.

Celiac nerve blocks have been performed without radiologic guidance, but recently several groups have reported computed tomography (CT)-guided techniques. The authors present a new technique of CT-guided celiac nerve block using an 18 gauge Teflon catheter, which permits a test block dose and permanent alcohol block with one procedure. The results of this new technique were very encouraging. Of nine cancer patients who had the test block, seven had good pain relief; these same patients had good pain control with the permanent block. Of six patients with pancreatitis, six had good pain relief from the test block, and three had some long-term relief from the permanent block.

Natural history of periprosthetic air on computerized axial tomographic examination of the abdomen following abdominal aortic aneurysm repair.

The presence of periprosthetic gas on computerized axial tomography (CT) of the abdomen following abdominal aortic reconstruction has been proposed to be a reliable indicator of prosthetic graft infection, a complication that requires intervention entailing significant mortality and morbidity. To evaluate the reliability of this finding in the early postoperative period, prosthetic grafts in 26 patients undergoing elective aneurysm repair were evaluated with postoperative CT examinations. Serial scans were obtained at mean intervals of 3, 7, and 52 days postoperatively. The presence or absence of periprosthetic air on CT scan was noted, and the results were correlated with aneurysm size as determined by preoperative ultrasound examination of the abdominal aorta or by measurements made during operation. Mean aneurysm size was 6.1 cm (range 4.5 to 10.6 cm). Periprosthetic air was demonstrated in 17 (65%) of the 26 patients studied within 1 week postoperatively. Patients with aneurysms larger than 6.0 cm were more likely to demonstrate periprosthetic air then those with smaller aneurysms (chi 2 = 5.024, p = 0.025). All patients found to have periprosthetic air had spontaneous resolution by late CT scanning obtained a mean of 52 days postoperatively (range 21 to 85 days). One patient died in the early postoperative period and two did not return for late scans. Only one patient demonstrated periprosthetic air as late as the thirty-second postoperative day, and this air had resolved by the seventieth postoperative day.(ABSTRACT TRUNCATED AT 250 WORDS)

NMR imaging of the abdomen: technical considerations.

Evaluation of nuclear magnetic resonance (NMR) imaging of the abdomen was done in 41 patients with focal and diffuse disorders of the liver and retroperitoneal and vascular abnormalities. Spin-echo technique was used in each situation with varying time to echo (TE) and repetition rates (TR). No single pulsing technique was optimal in all situations. Three false-negative NMR studies of 22 patients with focal lesions of the liver were attributed to incomplete coverage of the involved area or inappropriate pulsing technique. When appropriate technique was achieved, NMR was equal to computed tomography (CT) in detecting abdominal disorders, except in fatty infiltration of the liver. NMR was superior to CT in imaging vascular anatomy because of the inherent increased contrast produced by the absence of signal from flowing blood and the flexibility of imaging planes.

Nuclear magnetic resonance (NMR) imaging in the evaluation of the liver: a preliminary experience.

To determine the usefulness of nuclear magnetic resonance (NMR) in evaluation of the liver, 19 examinations were performed. A variety of pathological conditions were examined, and correlation was obtained with computed tomography, ultrasound, and radionuclide liver/spleen scanning. Nuclear magnetic resonance was as sensitive as the correlating imaging modalities in the detection of focal disease. Parenchymal abnormalities could be detected only in hemochromatosis. Several patients with diffuse disease did demonstrate evidence of portal hypertension, but no characteristic findings were noted within the liver parenchyma. Our preliminary investigation did not include T1 and T2 values and it is hoped that these will allow greater diagnostic utility in the detection of diffuse parenchymal disease.

Primary hyperaldosteronism: comparison of CT, adrenal venography, and venous sampling.

Twenty-nine patients with primary hyperaldosteronism were evaluated with computed tomography (CT), adrenal venous sampling, and adrenal venography. Twenty-three patients had aldosteronomas and six had bilateral adrenocortical hyperplasia. Sixteen (70%) of the adenomas were accurately located by CT. All nodules of 1.5 cm or larger diameter and 50% of nodules 1.0-1.4 cm in diameter were demonstrated. Nodules of less than 1.0 cm in diameter generally were not detected. High-resolution CT appeared more sensitive than standard CT (75% vs. 58%). Adrenal venous sampling for aldosterone assay was the most sensitive of the three methods, localizing 22 (96%) of the 23 adenomas. Eighteen (78%) of the adenomas were identified by adrenal venography, although two patients with bilateral cortical hyperplasia were mistakenly diagnosed as having a small adenoma. No such false-positive studies were encountered with CT or adrenal venous sampling.

Value of extravascular lung water measurement vs portable chest x-ray in the management of pulmonary edema.

Variability in technique and reporting time may limit radiographic quantitation of extravascular lung water by portable chest x-ray in critically ill patients. Using double indicator dilution technique and a commercially available lung water computer, we measured extravascular thermal volume (ETVL) in 14 patients with x-ray evidence of pulmonary edema and compared these results to x-ray quantitation of pulmonary edema. The diagnosis of pulmonary edema by interpretation of initial x-rays in each patient's series was 64% accurate as 5 of 14 patients had normal ETVL. Estimation of the magnitude of change in ETVL by radiologic interpretation was 42% accurate. No correlation was found between venous admixture Qsp/Qt, pulmonary capillary wedge pressure (WP) or ETVL values. Measurement of ETVL may aid in the care of critically ill patients with suspected pulmonary edema.

Digital subtraction angiography for preoperative evaluation of extremity tumors.

A retrospective study was undertaken to evaluate the role of digital subtraction angiography (DSA) in the surgical planning of musculoskeletal neoplasms. Thirteen patients with primary bone and soft-tissue tumors were examined by CT and DSA. Three patients also had conventional angiography. DSA yielded surgically useful information in 10 patients, comparable to that expected from conventional angiography. DSA was most helpful in demonstrating the presence or absence of major vessel involvement by tumor when this could not be ascertained definitely on CT. Demonstration of mass extent by CT was accurate in 11 patients. Results of this study suggest that the combination of CT and DSA is useful in the preoperative evaluation of selected extremity tumors and should diminish the need for conventional angiography.

Computed tomography in renal lymphoma.

The computed tomographic characteristics of 15 cases of renal lymphoma were evaluated. Initially the renal lesions are nodular but become confluent as the tumor progresses. In histiocytic and Hodgkin lymphoma, lesions can have the same attenuation values as normal renal parenchyma on noncontrast scans but less than normal parenchyma after contrast medium administration. Computed tomography is also useful in evaluating prognosis and response to therapy in renal lymphoma. Contrast material should be given if possible for evaluation of these lesions.

The effects of nuclear magnetic resonance on patients with cardiac pacemakers.

The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation in the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to time-varying magnetic fields.

Digital subtraction angiography of the abdominal aorta and renal arteries. Comparison with conventional aortography.

Digital subtraction angiography (DSA) was used to study the cardiovascular system in more than 400 patients and was specifically compared with conventional angiography of the aorta and renal arteries in 30 patients. For the renal arteries, the overall accuracy of DSA was 71% (50/70). Excluding 11 cases of inadequate visualization of the renal arteries on DSA, the sensitivity of the new technique was 93% (55/59) and the specificity 91.5% (54/59). Aortic disease, including intravascular clots and occlusions, was faithfully delineated by DSA.

Digital subtraction angiography of the human cardiovascular system.

Initial clinical application of a system for digital subtraction angiography (DSA) to the human cardiovascular system in 88 patients is reported. The equipment consisted of a specially designed computer system integrated with a fluoroscopic and radiographic apparatus for digitization, manipulation, and display of data. After intravenous injection of contrast material, adequate visualization of the heart and carotid, thoracic, abdominal, and femoral arteries was obtained with sufficient quality to obviate conventional angiography in many clinical settings. In this mode, nonselective opacification is obtained. However, DSA was also used to extend the capability of selective angiography. The availability of quantitative information permitted the determination of rates of transit of contrast material in various organs which may give insights of their physiologic performance.