Biomedical subjects

R Khazan

Publications and source records attributed to R Khazan.

10 recordsLinked to original sources

PubMed1999

Clinical decision making using teleradiology in urology.

OBJECTIVE: Using a personal computer-based teleradiology system, we compared accuracy, confidence, and diagnostic ability in the interpretation of digitized radiographs to determine if teleradiology-imported studies convey sufficient information to make relevant clinical decisions involving urology. Variables of diagnostic accuracy, confidence, image quality, interpretation, and the impact of clinical decisions made after viewing digitized radiographs were compared with those of original radiographs. MATERIALS AND METHODS: We evaluated 956 radiographs that included 94 IV pyelograms, four voiding cystourethrograms, and two nephrostograms. The radiographs were digitized and transferred over an Ethernet network to a remote personal computer-based viewing station. The digitized images were viewed by urologists and graded according to confidence in making a diagnosis, image quality, diagnostic difficulty, clinical management based on the image itself, and brief patient history. The hard-copy radiographs were then interpreted immediately afterward, and diagnostic decisions were reassessed. All analog radiographs were reviewed by an attending radiologist. RESULTS: Ninety-seven percent of the decisions made from the digitized radiographs did not change after reviewing conventional radiographs of the same case. When comparing the variables of clinical confidence, quality of the film on the teleradiology system versus analog films, and diagnostic difficulty, we found no statistical difference (p > .05) between the two techniques. Overall accuracy in interpreting the digitized images on the teleradiology system was 88% by urologists compared with that of the attending radiologist's interpretation of the analog radiographs. However, urologists detected findings on five (5%) analog radiographs that had been previously unreported by the radiologist. CONCLUSION: Viewing radiographs transmitted to a personal computer-based viewing station is an appropriate means of reviewing films with sufficient quality on which to base clinical decisions. Our focus was whether decisions made after viewing the transmitted radiographs would change after viewing the hard-copy images of the same case. In 97% of the cases, the decision did not change. In those cases in which management was altered, recommendation of further imaging studies was the most common factor.

Decision Making↗

PubMed1998

Differential activity of the G protein beta5 gamma2 subunit at receptors and effectors.

The G protein beta5 subunit differs substantially in amino acid sequence from the other known beta subunits suggesting that beta gamma dimers containing this protein may play specialized roles in cell signaling. To examine the functional properties of the beta5 subunit, recombinant beta5 gamma2 dimers were purified from baculovirus-infected Sf9 insect cells using a strategy based on two affinity tags (hexahistidine and FLAG) engineered into the N terminus of the gamma2 subunit (gamma2HF). The function of the pure beta5 gamma2HF dimers was examined in three assays: activation of pure phospholipase C-beta in lipid vesicles; activation of recombinant, type II adenylyl cyclase expressed in Sf9 cell membranes; and coupling of alpha subunits to the endothelin B (ETB) and M1 muscarinic receptors. In each case, the efficacy of the beta5 gamma2HF dimer was compared with that of the beta1 gamma2HF dimer, which has demonstrated activity in these assays. The beta5 gamma2HF dimer activated phospholipase C-beta with a potency and efficacy similar to that of beta1 gamma2 or beta1 gamma2HF; however, it was markedly less effective than the beta1 gamma2HF or beta1 gamma2 dimer in its ability to activate type II adenylyl cyclase (EC50 of approximately 700 nM versus 25 nM). Both the beta5 gamma2HF and the beta1 gamma2HF dimers supported coupling of M1 muscarinic receptors to the Gq alpha subunit. The ETB receptor coupled effectively to both the Gi and Gq alpha subunits in the presence of the beta1 gamma2HF dimer. In contrast, the beta5 gamma2HF dimer only supported coupling of the Gq alpha subunits to the ETB receptor and did not support coupling of the Gi alpha subunit. These results suggest that the beta5 gamma2HF dimer binds selectively to Gq alpha subunits and does not activate the same set of effectors as dimers containing the beta1 subunit. Overall, the data support a specialized role for the beta5 subunit in cell signaling.

Adenylyl Cyclases↗

PubMed1998

Fast MR imaging and the detection of small-bowel obstruction.

OBJECTIVE: Our aim was to determine whether fast MR imaging using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) MR sequence is accurate for diagnosis of small-bowel obstruction. MATERIALS AND METHODS: Forty-three nonconsecutive patients with suspected small-bowel obstruction were evaluated with HASTE MR imaging during a 12-month period. Images were retrospectively assessed for the presence, level, and cause of bowel obstruction. Data were compared with results of conventional radiography and findings at surgery when available. RESULTS: Of the 43 patients imaged, 29 patients had small-bowel obstruction revealed by unenhanced or contrast-enhanced radiography or by CT. Surgical confirmation was available in 21 patients. Small-bowel obstruction was shown by HASTE MR imaging in 26 (90%) of these 29 patients. HASTE MR images showed the correct level of obstruction in 19 (73%) of the 26 patients and showed the cause of obstruction in 13 (50%) of the 26 patients. CONCLUSION: With a high degree of accuracy, HASTE MR imaging can show the presence and level of small-bowel obstruction.

Adult↗

PubMed1997

Teleradiology in urology: comparison of digital image quality with original radiographic films to detect urinary calculi.

PURPOSE: Teleradiology systems are now being evaluated as a mechanism to provide rapid, accurate and cost-effective diagnostic radiographs to off-site physicians. Little data are available on the role and safety of teleradiology in urology. To address these issues a personal computer based system was developed to assess the diagnostic accuracy and ease of use of transmitted digital images when evaluating for urinary calculi. MATERIALS AND METHODS: A total of 100 plain abdominal scout films from excretory urograms performed during acute urological referrals was digitized on a laser scanner. The 10 megabyte files were transferred over public telephone lines and written to compact disks. The images were viewed on a 1280 x 1640 resolution monitor using "Imager-3D" software run on a 133 MHz. pentium personal computer with 32 megabytes of random access memory. Two faculty urologists and 2 urology fellows each looked at 50 original radiographs and 50 digital images. Diagnostic interpretations of the presence and location of calculi were recorded, and confidence in the diagnosis, assessment of image quality and diagnostic difficulty were scored using a numerical scale. RESULTS: The accuracy for all readers was 86.5% for plain radiographs and 81.5% for digital images (p >0.2). There was no statistical difference between faculty and fellows. Diagnostic accuracy did not differ between plain films and screen images when the results were assessed with respect to image quality, diagnostic difficulty or the reader confidence in the diagnosis (p >0.1). Compared to plain films, more screen images were classified as lower image quality (60 versus 40%) and the diagnostic confidence was lower (low and medium grade 50 versus 35%), although this did not interfere with diagnostic accuracy. CONCLUSIONS: These data imply that a high quality affordable teleradiology system is effective and accurate compared to plain films for assessing urinary calculi.

Humans↗

PubMed1996

MR urography using HASTE imaging in the assessment of ureteric obstruction.

OBJECTIVE: The purpose of this study was to evaluate an MR sequence using half-Fourier acquisition single-shot turbo spin-echo (HASTE) imaging in the assessment of ureteric obstruction. SUBJECTS AND METHODS: We prospectively evaluated 111 kidneys in 56 consecutive patients with HASTE MR urography and compared that imaging technique with excretory urography. The HASTE sequence was used to acquire images in the axial, sagittal, and coronal planes while patients held their breath. Level of obstruction and ureteric diameter were assessed, and the time required to determine the level of obstruction by both techniques was noted. RESULTS: With HASTE MR urography, we correctly diagnosed obstruction in 41 (100%) of 41 kidneys. Of the obstructed kidneys in which the ureter was shown by both excretory urography and MR urography, agreement was high (kappa = .642) between the two imaging techniques regarding the level of obstruction. HASTE MR urography showed perirenal fluid in 20 (87%) of 23 acutely obstructed kidneys. HASTE MR urography showed the site of obstruction on the first 13-sec scan in 33 (80%) of 41 kidneys. CONCLUSION: HASTE MR urography accurately and rapidly shows the level and degree of ureteric obstruction. It can be used to differentiate between acute and chronic obstruction on the basis of its ability to show perirenal fluid.

Acute Disease↗

PubMed1996

Choledocholithiasis: evaluation with MR cholangiography.

OBJECTIVE: We performed this study to evaluate the usefulness of a new T2-weighted MR sequence using a half-Fourier acquisition single-shot turbo spin-echo (HASTE) technique in the diagnosis of bile duct stones. SUBJECTS AND METHODS: We prospectively evaluated 23 patients with suspected bile duct calculi using HASTE MR cholangiography and compared that imaging technique with endoscopic retrograde cholangiography and sonography. The study group consisted of 15 women and eight men who were 42-89 years old. Patients were imaged in the axial, coronal, and sagittal planes with a 1.5-T MR scanner using a body coil. Acquisitions of 13 sec each allowed images to be obtained in a single breath-hold. All images were interpreted by two radiologists in a double-blinded fashion. The presence, number, and size of stones were noted, and common bile duct dilatation was assessed. RESULTS: Fifteen of the 23 patients were proven to have common bile duct stones. Stone size ranged from 3 mm to 35 mm (mean, 11 mm). HASTE MR cholangiography revealed stones in 14 (93%) of 15 patients; sonography revealed stones in nine (60%) of 15 patients. In 12 patients, the common bile duct was dilated, as shown by endoscopic retrograde cholangiography, HASTE MR cholangiography, and sonography. On HASTE MR cholangiograms, we measured the diameter of the bile duct in all patients. The mean diameter was 11 mm, which correlated well (r = .82) with a mean diameter of 13.5 mm as measured on endoscopic retrograde cholangiograms. CONCLUSION: HASTE MR cholangiography can noninvasively and rapidly reveal the presence of stones in the common bile duct and allows readers to assess the degree of biliary dilatation. The sequence should be considered as an alternative to endoscopic retrograde cholangiography in patients with clinical evidence of bile duct calculi and in those for whom endoscopic retrograde cholangiography is impossible.

Adult↗

PubMed1994

Efficacy and safety of iopromide for excretory urography.

RATIONALE AND OBJECTIVES: Iopromide is a nonionic monomeric contrast agent. Initial laboratory and clinical data have shown that it is relatively safe. Efficacy for excretory urography has been shown to be good, comparable with other low-osmolality agents. The authors attempted to confirm these impressions in a randomized, double-blind comparison with equivalent doses of ioversol and iopamidol. METHODS: Two hundred adult patients undergoing excretory urography were studied. One hundred received iopromide, 40 received ioversol, and 60 received iopamidol (300 mg I/kg) as an intravenous bolus. Urographic films (obtained 1, 5, 15, and 20 minutes after the bolus, and postvoid) were interpreted by an observer blinded to contrast type. Visualization of renal parenchyma, pelvis and calyces, ureters, and bladder was independently assessed as excellent, good, poor, or nonvisualized. Vital signs were recorded before, 30 to 60 minutes after, and 24 hours after injection. Adverse reactions were sought, physical examinations were performed, and standard hematology and serum chemistry values were measured before and 1 day after injection; a 72-hour serum creatinine level was also measured. RESULTS: Ninety-eight percent of visualization scores were good or excellent; no significant differences among iopromide, iopamidol, and ioversol were found, nor were there any significant differences among groups in vital signs. Only one patient experienced a contrast-related physical examination change (subcutaneous extravasation). No significant changes with regard to hematology or serum chemistry values were observed; there was no contrast-induced nephropathy. Mild adverse reactions were experienced by 10% of patients; there were no significant differences in reaction rates among contrast agents. CONCLUSIONS: Iopromide at a dose of approximately 300 mg I/kg is safe and effective as an excretory urographic agent and is comparable in performance with ioversol and iopamidol.

Adult↗

PubMed1993

Renal cell carcinoma with situs inversus totalis.

A case of renal cell carcinoma in a patient with situs inversus totalis is reported. Only 8 cases of malignant neoplasms have been reported in situs inversus totalis, and our case represents the second case report of renal cell carcinoma in a patient with situs inversus totalis. The frequency of situs inversus totalis is between 1 in 8,000 and 1 in 20,000. Cardiac and pulmonary anomalies are common in patients with situs inversus totalis. Renal anomalies, including agenesis, dysplasia, hypoplasia, ectopia, polycystic kidney, and horseshoe kidney, have been reported. Because of the association between situs inversus and cardiac, pulmonary, renal, and vascular anomalies, management of the patient with situs inversus and urologic disease requires careful preoperative evaluation.

Aged↗

PubMed1991

Emphysematous pyelitis and emphysematous pyelonephritis characterized by computerized tomography.

We report three cases of emphysematous pyelonephritis, all of them associated with perinephric emphysema, and one case of emphysematous pyelitis to demonstrate the value of computerized tomography (CT) in both diagnosis and patient management. The differentiation between air in the collecting system (emphysematous pyelitis), air within the parenchyma (emphysematous pyelonephritis), and air in the perinephric space (perinephric emphysema) may have significant prognostic (survival) and therapeutic (medical vs surgical) implications. Computerized tomography is currently the best method for demonstrating intrarenal air and for characterizing the location of that air (intracalyceal, intraparenchymal, perinephric, or pararenal).

Adult↗

PubMedDate not supplied

MR cholangiography in biliary obstruction using half-Fourier acquisition.

PURPOSE: Our goal was to evaluate biliary obstruction using a T2-weighted, turbo, SE MR sequence with half-Fourier acquisition (HASTE). METHOD: A prospective evaluation of 21 consecutive patients with clinical evidence of obstructive jaundice was carried out comparing HASTE MR cholangiography (MRC) to endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography. A control group of five normal volunteers was also evaluated. The study group was imaged with a 1.5 T MR scanner using a body coil. The HASTE sequence was applied in axial, coronal, and oblique sagittal planes. Ultrafast acquisition scanning times allowed the use of a single breath hold. Bile duct dilatation, level of obstruction, and cause of obstruction were assessed on both imaging modalities by two radiologists blinded to the clinical diagnosis and to each other's results. RESULTS: All studies were interpretable with anatomy well seen in 82% of the cases. MRCs of a normal control group were correctly interpreted. The presence of biliary dilatation was accurately depicted by HASTE MRC in 100% of patients with complete interobserver agreement. The level of obstruction was depicted correctly in 87% of patients with 93% interobserver agreement. The right main duct was seen by MRC in 80% of obstructed systems. The left main duct was seen in all obstructed patients. The gallbladder was identified in 88% of patients by MRC. Common bile duct stricture and stones could be differentiated as a cause of obstruction in all cases. CONCLUSION: MRC using the HASTE imaging sequence can safely and accurately depict the presence and level of biliary obstruction. The fast acquisition time of 13 s/scan makes the technique suitable for uncooperative and ill patients. HASTE MRC should be considered an alternative procedure to direct cholangiography in selected patients.

Aged↗