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Biomedical subjects

N R Dunnick

Publications and source records attributed to N R Dunnick.

At least 73 records · Page 4Linked to original sources
PubMed1990

Ovarian vein thrombosis in oncology patients: CT detection and clinical significance.

During a 13-month period, ovarian vein thrombosis (OVT) was detected with CT in six patients with malignant tumors, five of whom were receiving high-dose chemotherapy at the time of diagnosis. None of these patients belonged to previously recognized risk groups. Unlike most patients with postpartum or postoperative OVT, only one of our patients was symptomatic, and none had related CT findings, such as uterine enlargement or other enhancing pelvic masses. Patients with malignant tumors, particularly those undergoing chemotherapy, are at risk for developing OVT. As OVT is often asymptomatic in these patients, and thrombus may resolve without treatment, anticoagulation may not be routinely necessary.

Adult↗
PubMed1990

Transitional cell carcinoma of the pelvicalices and ureter.

Transitional cell carcinoma accounts for about 90% of all cancers of the renal pelvis and more than 90% of all cancers of the ureter. Its clinical presentation is nonspecific. Radiology plays a critical role in detection, evaluation, and disease monitoring. We reviewed the pathologic and clinical features of transitional cell carcinoma of the upper urinary tract, with attention to its radiology appearance, staging, and treatment.

Carcinoma, Transitional Cell↗
PubMed1990

Obliteration of the fat surrounding the celiac axis and superior mesenteric artery is not a specific CT finding of carcinoma of the pancreas.

Partial or complete obliteration of the fat surrounding the celiac axis and superior mesenteric artery on CT is considered so characteristic of pancreatic carcinoma that many consider it diagnostic. However, this finding may be present on CT scans of some treatable tumors. During a 2-year period, we retrospectively collected 10 cases of nonpancreatic tumors that obliterated the fat surrounding the celiac axis and/or superior mesenteric artery. Four patients had metastatic disease, three had lymphoma, two had primary small-bowel adenocarcinoma, and one had a diffuse retroperitoneal endocrine tumor. The scans were analyzed for presence, location, and morphology of the mass and biliary and/or pancreatic ductal dilatation. Of the patients with metastatic disease, three had focal, retropancreatic, periceliac masses without ductal dilatation. One had an infiltrative retroperitoneal process enveloping the pancreas and causing biliary dilatation. Of the patients with lymphoma, two had focal masses in the mesenteric root without ductal dilatation, and one had an infiltrative retroperitoneal process. Of the two patients with primary carcinoma of the small bowel, one had a mesenteric mass without ductal dilatation and the other had an infiltrative retroperitoneal process enveloping the pancreatic head and obstructing the ducts. The patient with the neuroendocrine tumor had an infiltrative retroperitoneal process enveloping the pancreas without ductal dilatation. Obliteration of the fat surrounding the celiac axis and superior mesenteric artery is not a specific CT finding of carcinoma of the pancreas. One cannot rely solely on its presence for the diagnosis of pancreatic carcinoma but should use other important findings such as a focal pancreatic mass and ductal dilatation.

Adenocarcinoma↗
PubMed1989

Role of linear tomography in evaluation of patients with nephrolithiasis.

One hundred twenty-four consecutive patients with suspected or known nephrolithiasis were referred for evaluation by linear tomography. Renal calculi were detected in 98 patients (79%). Linear tomography revealed more renal calculi than did preliminary KUB films in 46 patients (37%), although in only 10 cases (8%) was the tomogram positive if the KUB was negative. Exact quantification of the numbers and locations of renal stones is important in patients to be managed metabolically, and in those being evaluated in advance of or following percutaneous or extracorporeal lithotripsy.

Humans↗
PubMed1989

Dynamic, incremental computed tomography using a high heat capacity tube, solid-state detector, and automated injector. Potential in body imaging.

Using a new graphite tube, a prototype solid scintillating detector, and an automated injector, improvements were made in body computed tomography image quality. First, more scans with shorter interscan delay could be obtained with the improved tube. Second, liver image quality was improved with the use of higher techniques and a more consistent contrast bolus delivery with a mechanical injector. Last, body surveys were improved because the higher heat capacity tube provided the ability to rapidly scan and examine an entire region during the injection of contrast.

Automation↗
PubMed1989

Interventional uroradiology.

Major interventional uroradiologic techniques including percutaneous nephrostomy, vascular augmentation and reduction procedures, percutaneous cyst aspiration, chronic peritoneal dialysis catheter manipulation and urethroplasty are reviewed. A brief history of the development and techniques for performing these procedures are included. The results of clinical series are assessed and their role in patient management is addressed. The development of these procedures has had a significant impact on patient care by providing effective nonoperative therapy.

Angioplasty, Balloon↗
PubMed1989

Intravenous digital subtraction renal angiography: use in screening for renovascular hypertension.

Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension.

Adult↗
PubMed1989

Prospective analysis of strategies for diagnosing renovascular hypertension.

Renovascular hypertension is a potentially curable form of high blood pressure. However, it is unclear how best to select patients who are likely to have renovascular hypertension, what diagnostic strategy to use in these selected patients, and how to predict the hemodynamic significance of a renal artery stenosis. We determined the prevalence of renovascular hypertension in adults who exhibited suggestive clinical features. In these clinically selected patients, we then determined the test characteristics of various diagnostic and potential screening tests. Renovascular hypertension was diagnosed if correction of renal artery stenosis resulted in decreased blood pressure. Of the 66 hypertensive adults evaluated, 11 (16.7%) had renovascular hypertension. Captopril-stimulated peripheral renin activity detected renovascular hypertension with 73% sensitivity, 72% specificity, 38% positive predictive value, and 92% negative predictive value. Less optimal combinations of sensitivity and specificity were found for differential glomerular filtration rate renography, differential effective renal plasma flow renography, and selective renal vein renin ratios, each performed after a single dose of captopril. Intravenous digital subtraction renal angiography detected all patients with renovascular hypertension and was normal in 71% of patients with essential hypertension. To evaluate potential screening tests for renovascular hypertension, we calculated predictive values applied to a low prevalence population. If the observed sensitivities and specificities apply to a population with 5% prevalence of renovascular hypertension, captopril-stimulated peripheral renin would have a positive predictive value of 12% and a negative predictive value of 98%. In 16 patients with known renal artery stenosis, neither the captopril-stimulated renal vein renin ratio nor captopril-stimulated differential renography accurately predicted blood pressure response to correction of the stenosis. We conclude that clinical criteria can identify a subgroup with 16.7% prevalence of renovascular hypertension. In this high prevalence group, intravenous digital subtraction renal angiography will identify virtually all patients with renovascular hypertension, and a normal study will be sufficient to exclude renovascular hypertension. In unselected hypertensive patients, screening with captopril-stimulated peripheral renin activity may be the most useful and efficient procedure for identification of patients with renovascular hypertension. Functional tests do not accurately predict the hemodynamic significance of a renal artery stenosis.

Adult↗
PubMed1989

MR evaluation of adrenal masses at 1.5 T.

We retrospectively studied the value of MR imaging at 1.5 T to distinguish between nonadenomatous (n = 17) and adenomatous (n = 15) adrenal masses on the basis of (1) signal-intensity ratios on T1- and T2-weighted spin-echo images, (2) T2 relaxation times, and (3) T2 relaxation-time ratios. Univariate and then multivariate logistic regression were applied to these quantitative parameters to determine which of these best discriminated nonadenomas from adenomas, and whether or not more than one of these parameters improved the prediction. The adrenal mass/liver signal-intensity ratio on T2-weighted spin-echo images could not be used to differentiate nonadenomas from adenomas. Adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images, adrenal/liver T2 relaxation-time ratios, and adrenal mass T2 relaxation times were best for distinguishing nonadenomas from adenomas. By using a T2 value of greater than 61 msec, the true-positive ratio/false-positive ratio of differentiating nonadenomas from adenomas was 100%/20%; at greater than 82 msec, it was 64%/0.06%. The adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images and the adrenal/liver T2 relaxation-time ratios showed similar inherent discriminatory capacity. Overlap remains despite the use of these parameters. On the basis of this preliminary information, we conclude that MR has merit for the characterization of adrenal masses at 1.5 T. T2 relaxation time of the adrenal mass shows the greatest promise for discriminating nonadenomas from adenomas.

Adenoma↗
PubMed1989

Current use of low-osmolality contrast agents: results of a survey.

Members of the Society of Cardiovascular and Interventional Radiology and the Society of Uroradiology were surveyed to assess both current practice and determinants of use of low-osmolality contrast agents (LOCA). Of 715 questionnaires mailed, 229 were returned (32%). Many indicated that the responses referred to the practice of a group, rather than to an individual. Two thirds of the responses indicated that the choice of agent was made by the radiologist alone; one third shared the decision with administrators. Approximately 40% of respondents use written guidelines, but this percentage was higher when administrators were involved in the decision. Almost all (99%) obtained written informed consent--one third for all procedures that use contrast material and two thirds for angiographic studies only. Four percent noted the availability of LOCA in obtaining consent. Overall, LOCA were used for most angiographic procedures by 38% and for most IV studies by only 9% of respondents. All used them for at least some angiographic studies, and all but 2% used them for some IV studies. The major indications for use in both angiographic and IV studies were a prior major (but not minor) reaction and renal dysfunction. Anticipated patient discomfort also was important for intraarterial use. LOCA were used most often for peripheral and pulmonary arteriography. When LOCA were used, nonionic agents were preferred to low-osmolality ionic dimeric contrast agents for coronary angiography and venography, but this preference was essentially reversed for peripheral arteriography. This survey suggests that IV use of LOCA is much less frequent than intraarterial use and that use is individualized to certain risk factors and certain examinations. Guidelines for use are often in place, but this is clearly not universal. The importance of informed consent for use of contrast agents and of the appropriate role for LOCA remains unsettled.

Angiography↗
PubMed1988

CT and MRI of adrenal lesions.

Adrenal lesions can be divided into those that result in clinical syndromes due to excess hormone elaboration and those that are nonhyperfunctioning. Computed tomography (CT) is usually adequate to assess the adrenal glands in patients with hyperfunctional disease. Occasionally supplementation with radionuclide studies, magnetic resonance (MR) or venous sampling, is required. Lesions which are not hyperfunctioning are often detected as an incidental mass. The CT and MR characteristics often allow a confident diagnosis based on their imaging characteristics. The adrenal glands are a common site of metastatic disease which can be detected by CT and further characterized by MR or biopsy if the stage of disease is uncertain.

Adrenal Gland Diseases↗
PubMed1988

Sonography of small renal masses with indeterminant density characteristics on computed tomography.

Nine small renal masses with attenuation coefficients greater than 20 HU on computed tomography (CT) were termed indeterminate for cyst or renal cell carcinoma. Correlative sonography identified the fluid-filled internal architecture in four of five cysts and correctly characterized as solid four small renal cell carcinomas. The sonogram was particularly valuable in assessing masses that were indeterminate on CT when enhancement was equivocal or when intravenous contrast could not be administered. We conclude that sonography is extremely useful as a noninvasive procedure in evaluating the occasional small renal mass with CT number greater than 20 HU.

Carcinoma, Renal Cell↗
PubMed1988

Povidone-iodine sclerosis of pelvic lymphoceles: a prospective study.

Twelve patients presented for percutaneous catheter drainage of 13 postoperative pelvic lymphoceles. Six patients with 7 lymphoceles were treated with povidone-iodine sclerosis prior to catheter removal. Only 1 lymphocele (which continued to drain large amounts of fluid during and after the sclerosis procedure) recurred. Six patients with 6 lymphoceles had their percutaneous catheters removed without sclerosis. Fluid collections recurred in 3 instances, necessitating repeat percutaneous drainage (2 patients) or surgery (1 patient). Percutaneous therapy is the treatment of choice for patients with postoperative lymphoceles. Povidone-iodine sclerosis is often effective in preventing reaccumulation of fluid once the lymphocele cavity is collapsed.

Adult↗