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Biomedical subjects

R H Cohan

Publications and source records attributed to R H Cohan.

At least 19 recordsLinked to original sources
PubMed1999

Orthotopic neobladder reconstruction: findings on excretory urography and CT.

OBJECTIVE: The excretory urographic and CT appearance of orthotopic ileal neobladder reconstruction after cystectomy and its complications are described. MATERIALS AND METHODS: We retrospectively reviewed the excretory urograms and CT scans of 32 patients (29 men and three women, 35-76 years old) with transitional cell carcinoma of the bladder who underwent orthotopic neobladder reconstruction with anastomosis to the native urethra after cystectomy. The radiologic review consisted of 25 excretory urograms in 20 patients and 37 CT scans in 21 patients. RESULTS: On excretory urography, the afferent segment of the neobladder was identified as a contrast-filled structure in all 20 patients, and was located in the right lower quadrant in 18 (90%). On CT, the afferent segment and the neobladder were identified in all 21 patients. Delayed imaging performed after initial scanning in 12 (57%) of 21 patients was helpful for revealing detailed anatomy such as the ureteral-afferent limb anastomoses. Complications occurred in two patients and were caused by a lymphocele in one and a urine leak from the neobladder in the other. In six other patients we found evidence of recurrent or metastatic tumor or both: two had local pelvic recurrence and pelvic nodal metastases, two other patients had metastatic nodal disease, one patient had a malignant distal ureteral stricture, and the sixth patient had distant osseous metastases. CONCLUSION: Orthotopic neobladder reconstruction after cystectomy has a characteristic appearance on both excretory urography and CT. Knowledge of this appearance and the altered anatomy is useful to recognize complications and tumor recurrence. Delayed images during excretory urography and CT are useful to define the ureteral-afferent limb anastomosis with the neobladder and also to differentiate between postoperative collections.

Adult↗
PubMed1997

Iodinated contrast material in uroradiology. Choice of agent and management of complications.

Many conditions seen by urologists require imaging examinations with iodinated radiographic contrast material as a key part of the primary evaluation of the patient. A basic understanding of contrast media, risks of administration, choice of agents, and premedication regimens for high-risk patients, is beneficial in helping patients prepare for their examinations. Urologists may be the primary physicians administering contrast material or may be working with radiologists in the care of patients receiving contrast agents. Because contrast reactions may occur unexpectedly, even during examinations in which the agents are not given intravenously, urologists should be able to recognize and treat the various types of adverse reactions.

Adrenal Cortex Hormones↗
PubMed1997

Helical CT for detection and characterization of renal masses.

Helical CT permits the radiologist to image the kidney continuously, eliminating the chances of scanner misregistration. In addition, the kidneys can now be imaged during essentially any phase of contrast material enhancement. Although this offers greater flexibility to the imager, a number of potential problems with helical CT must be considered, particularly when it is performed during the cortical phase of renal enhancement. This article reviews both the advantages and potential pitfalls of helical CT when used for both detection and characterization of renal masses.

Humans↗
PubMed1997

Local reactions after injection of iodinated contrast material: detection, management, and outcome.

RATIONALE AND OBJECTIVES: The authors assessed the frequency, sequelae, and risk factors of extravasation of intravenously administered iodinated contrast media. MATERIALS AND METHODS: All patients with local reactions after intravenous injection of contrast media between November 1994 and December 1996 were studied. Comparison was made with data obtained from a control group of 100 patients with no local reactions who underwent contrast material-enhanced computed tomography (CT). RESULTS: Local reactions were reported in 56 (0.25%) of 22,254 patients who received intravenous injections of iodinated contrast media. Fifty-one patients experienced extravasation, and five patients experienced local irritation in the absence of clinically detectable extravasation. Extravasation occurred during CT (n = 46), urography (n = 4), and venography (n = 1). Contrast material was nonionic in 37 cases and conventional ionic in 14 cases of extravasation. Extravasated volumes exceeded 30 mL in 22 patients and 100 mL in six patients. Forty-five (80%) of 56 patients with local reactions had complete resolution of symptoms within 24 hours. Only four patients had symptoms for more than 48 hours. No surgery was required. Compared with the control group, patients with extravasation were significantly more likely to have been injected with small-bore catheters (21 or 22 gauge) and to have been injected at low or high rates. CONCLUSION: Symptoms of contrast medium extravasation usually resolve quickly. In patients with extravasation, injections are more likely to have been performed with techniques that vary from normal practice.

Blister↗
PubMed1996

Cystic renal masses: a reevaluation of the usefulness of the Bosniak classification system.

RATIONALE AND OBJECTIVES: We evaluated the utility of the Bosniak system for classifying cystic renal masses on computed tomography (CT) scans. METHODS: The CT scans of 20 patients with 24 cystic renal masses that were subsequently surgically removed or biopsied were reviewed retrospectively. Masses were categorized using the Bosniak system and were correlated with the pathology results. RESULTS: The final pathology results of the cystic renal masses were as follows: Seven of seven category I lesions were benign, one of five category II lesions was benign, zero of four category III lesions were benign, and zero of six category IV lesions were benign. Neither of two unclassifiable cystic lesions were benign. The average enhancement of lesions in categories II, III, and IV was 6.3, 2.3, and 27.6 Hounsfield units (H), respectively. The two uncategorizable lesions had a mean enhancement of 26.8 H. CONCLUSION: The results of our study serve to underscore some limitations of the Bosniak classification system because most of our category II and all of our category III lesions were malignant, suggesting that minimally complex cystic renal masses may contain malignant cells. Contrast enhancement of less than 10 H was demonstrated in lesions in categories II and III.

Adenocarcinoma↗
PubMed1996

Improvement of faculty teaching performance: efficacy of resident evaluations.

RATIONALE AND OBJECTIVES: We assessed the effects on the perceived quality of faculty teaching of a resident evaluation form that solicits specific comments on faculty strengths and weaknesses. METHODS: An evaluation form was devised that rated faculty on a scale of 1-10 in teaching conference quality, availability, efficiency, and teaching. The form requested constructive comments on faculty strengths and weaknesses. The forms were completed anonymously by residents at all levels. Individual results and means for the department were tabulated and provided to each faculty member in a personal interview. Change in performance was assessed by comparing faculty evaluation scores for 2 consecutive years. RESULTS: The mean faculty scores for teaching conference quality, availability, efficiency, and teaching increased from 7.8, 7.9, 7.9, and 7.7 to 8.1, 8.3, 8.3, and 8.1 in each of the respective areas. The scores of the faculty members who initially received the 10 lowest scores rose to an even greater extent (from 6.2, 6.2, 6.0, and 6.0 to 6.8, 7.4, 7.3, and 6.8 in each of the respective areas), whereas the scores of the faculty members who initially received the 10 highest scores remained relatively constant. CONCLUSION: The perceived quality of certain focused aspects of resident teaching can be modified by use of resident evaluations that solicit specific suggestions for improvement. With appropriate feedback, this is an effective tool for improving the teaching performance of radiology department faculty, particularly those considered to be the weakest teachers.

Faculty, Medical↗
PubMed1996

Urethral disruption with urinary extravasation: a delayed complication of pancreatic transplantation.

PURPOSE: To describe the radiographic features and potential causes of urethral disruption in pancreas transplant recipients. MATERIALS AND METHODS: Eight episodes of urinary extravasation were depicted with retrograde urethrography in five male patients who had undergone pancreatic transplantation. The patients' medical records were reviewed to determine a cause of the extravasations. RESULTS: Four extravasations occurred at the proximal (deep) bulbar urethra, three at the bulbomembranous junction of the urethra, and one at the distal bulbar urethra. Four of eight cases of extravasation were preceded by recent cystoscopy or placement of a Foley catheter; one case was preceded by possible urethral injury due to a fall. CONCLUSION: Urethral disruption occurs as a complication of pancreatic transplantation. It has so far been seen only in male patients and occurs at the bulbar urethra or bulbomembranous junction. If the treating physician is unaware of this condition, diagnosis and institution of appropriate therapy may be delayed. Recent prior urinary tract instrumentation or trauma may be predisposing factors in urinary extravasation.

Anastomosis, Surgical↗
PubMed1996

Adverse reactions to gadolinium contrast media: a review of 36 cases.

OBJECTIVE: We investigated the frequency, manifestations, and severity of reactions to gadolinium contrast media in patients who underwent MR imaging at a single institution. MATERIALS AND METHODS: We reviewed the quality assurance records of 21,000 patients to whom gadolinium contrast media were administered at our institution between January 1990 and October 1994. Of these patients, 36 had adverse reactions. All 36 patients were evaluated by a radiologist at the time of the adverse reaction, and a written report of the findings was completed immediately. RESULTS: We classified adverse reactions into four groups: mild nonallergic reactions (15 patients with nausea or vomiting), mild reactions resembling allergy (12 patients with hives, diffuse erythema, or skin irritation), moderate reactions resembling allergy (seven patients with respiratory symptoms), and life-threatening reactions resembling allergy (two patients with severe chest tightness, respiratory distress, and periorbital edema). Eleven of these 36 patients who had adverse reactions also had an unusual local reaction of skin discomfort in the extremity through which gadolinium was injected. Four of the 36 patients with adverse reactions had histories of adverse reactions to iodinated contrast media. All four of these patients and one of the remaining 32 patients with adverse reactions required treatment. No patients with adverse reactions died. CONCLUSION: Although gadolinium contrast media are safe, we found that patients had adverse reactions at a frequency greater than we expected. Severe anaphylactoid reactions occurred in two patients (0.01%). This rate exceeds the rate of 0.0003% reported in the literature. The indexes of suspicion for the occurrence of reactions to gadolinium, and both the documentation and the management of adverse reactions, must be as rigorous for reactions associated with MR imaging contrast agents as they are for reactions associated with iodinated contrast media.

Anaphylaxis↗
PubMed1996

Treatment of adverse reactions to radiographic contrast media in adults.

Prompt recognition and treatment can be invaluable in blunting an adverse response of a patient to radiographic contrast material and may prevent a reaction from becoming severe or even life-threatening. Radiologists and their staff should review treatment procedures regularly (at least annually) so that each staff in attendance can accomplish his or her role efficiently. Knowledge, training, and preparation are crucial in guaranteeing appropriate and aggressive therapy in the event of an adverse contrast-related event.

Anaphylaxis↗
PubMed1995

Small echogenic renal masses: how often is computed tomography used to confirm the sonographic suspicion of angiomyolipoma?

OBJECTIVES: Although renal angiomyolipoma (AML) has a typical ultrasound appearance, many authorities suggest that a computed tomography (CT) scan be obtained to confirm the diagnosis because small echogenic renal cell carcinomas can simulate AML. Our study evaluates the actual follow-up in such patients and factors that may affect whether CT confirmation is recommended or obtained. METHODS: From 1986 through 1992, 36 patients had an ultrasound diagnosis of probable renal AML (well-circumscribed, homogenously echogenic mass). In each case the patient's age, symptoms, ultrasound results and recommendations, and imaging follow-up were recorded. RESULTS: CT confirmation of the sonographic diagnosis was recommended in only 11 of 36 (31%) patients. Only 7 of these 11 patients actually underwent CT, 5 of whom had the diagnosis confirmed by CT detection of intratumoral fat. Ten of 23 patients (43%) over 50 years of age had CT recommended, whereas only 1 of 13 (8%) patients under age 50 years did (P < 0.05). CT confirmation was recommended for 5 of 13 (38%) lesions greater than 10 mm and for 6 of 23 (26%) smaller masses. None of the 9 patients under age 50 years with small masses (less than 10 mm) had CT recommended. CONCLUSIONS: Although many authorities recommend CT to confirm the sonographic diagnosis of renal AML, this algorithm is rarely followed in everyday clinical practice, especially in patients under age 50 years with masses less than 10 mm.

Adult↗
PubMed1995

Use of low-osmolar agents and premedication to reduce the frequency of adverse reactions to radiographic contrast media: a survey of the Society of Uroradiology.

PURPOSE: To assess the decisions made by uroradiologists regarding choice of type of intravenous contrast material (low-osmolar contrast media [LOCM] vs conventional ionic agents) and frequency of use of corticosteroid prophylaxis. MATERIALS AND METHODS: A questionnaire was mailed to 158 members of the Society of Uroradiology. There were 108 responses received, yielding a response rate of 68%. Results from 76 represented institutions were tabulated. RESULTS: Most respondents practice at institutions in which LOCM are used selectively rather than universally. Corticosteroid prophylaxis in patients at risk is used with similar frequency at both types of institutions. There is considerable diversity in pretreatment regimens (ie, type and dose of corticosteroid used). Although antihistamines are used by many uroradiologists (almost always in conjunction with corticosteroids), H2 receptor antagonists are used at only a few institutions. CONCLUSION: At institutions in which LOCM are used selectively, the majority of respondents use LOCM quite liberally, with most choosing these agents in patients at risk. Corticosteroid prophylaxis is widely used by respondents. There is much variation in the type of pretreatment regimen and its use in specific clinical settings.

Adrenal Cortex Hormones↗
PubMed1995

Abdominal aortic aneurysms: CT evaluation of renal artery involvement.

PURPOSE: To determine whether computed tomography (CT) assessment of the proximal extent of ruptured aneurysms can help the surgeon determine whether to initially clamp the pararenal aneurysm neck or the supraceliac aorta. MATERIALS AND METHODS: CT scans and medical records were reviewed and compared for 30 patients with ruptured abdominal aortic aneurysms (AAAs) who underwent immediate surgical repair. RESULTS: For 49 of 50 vessels in 25 patients, the authors correctly predicted at CT that AAAs originated caudal to the main renal artery origins. They also predicted that nine main renal arteries in five patients originated directly from the AAAs, but this was correct in only five arteries. Suprarenal clamping was required in all five patients. Infrarenal clamps were used before reconstruction in all 12 of the patients whose AAAs appeared to originate at least 30 mm below the main renal arteries. CONCLUSION: CT can help predict whether an initial aortic clamp can be placed caudal to the main renal artery orifices. Its use can be predicted with 100% certainty only when an aneurysm appears to originate at least 3 cm caudal to the origin of the main renal artery.

Aged↗
PubMed1995

Renal masses: assessment of corticomedullary-phase and nephrographic-phase CT scans.

PURPOSE: To evaluate the role of thin-section helical computed tomography (CT) performed during the corticomedullary phase (CMP) and nephrographic phase (NP) of contrast enhancement in the detection and characterization of renal masses. MATERIALS AND METHODS: Renal CT scans and medical records of 33 patients were retrospectively reviewed. In all examinations, 5-mm-thick, contiguous, helical-mode scans were obtained before and 40 seconds after initiation of dynamic bolus injection of contrast material (CMP images); 5-mm-thick, contiguous, axial-mode scans were obtained after completion of CMP scanning (NP images). RESULTS: At review of CMP, NP, and combination images, 259, 389, and 417 lesions, respectively, were identified. The greatest difference in detection occurred in the renal medulla, with 25 lesions identified on CMP images and 111 lesions identified on NP images. False-positive results occurred when CMP images were reviewed without NP images. CONCLUSION: CT scans obtained only during the CMP of contrast enhancement fail to depict many renal masses that are easily seen on NP images.

False Positive Reactions↗
PubMed1995

Positional variation in the Whitaker test.

PURPOSE: To describe positional variation in the outcome of the Whitaker test. MATERIALS AND METHODS: The authors retrospectively reviewed the cases of six patients in whom the pressure gradient during Whitaker testing varied by at least 10 cm of water and changed from normal ( < or = 13 cm of water) to abnormal ( > 13 cm of water) when patients were placed in different positions. RESULTS: Four patients had obstruction only in nonstandard positions. All had intermittent symptoms, and three had ureteral kinks at fluoroscopy. Two patients with ileal conduits had abnormal results in the standard position but normal results at repositioning related to compression of the conduits (seen as conduit distention at fluoroscopy). All six had undergone urinary tract surgery. Gradient differences with positional change ranged from 10 to > 38 cm of water. CONCLUSIONS: Whitaker testing in different positions may help identify intermittent obstructions that might otherwise go undetected or prevent inappropriate diagnosis of obstruction. Intermittent or unexplained symptoms, tortuous ureters, malpositioned kidneys, or previous surgery are indications for provocative positional testing.

Adult↗