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Biomedical subjects

M E Tublin

Publications and source records attributed to M E Tublin.

At least 19 recordsLinked to original sources
PubMed2001

Uterine artery embolization for the treatment of adenomyosis: clinical response and evaluation with MR imaging.

OBJECTIVE: This study was performed to evaluate the MR imaging appearance and clinical response of patients undergoing uterine artery embolization for the treatment of menorrhagia due to adenomyosis. MATERIALS AND METHODS: A retrospective review of 15 patients with adenomyosis and menorrhagia who underwent uterine artery embolization was performed. The diagnosis of adenomyosis was based on established MR imaging criteria. Clinical response was assessed at a minimum of 3 months after embolization. Follow-up MR imaging was performed 6 months after embolization. RESULTS: Of the 15 patients in this study, five had diffuse adenomyosis without evidence of uterine fibroids, one had focal adenomyosis without evidence of uterine fibroids, and the remaining nine had adenomyosis with one or more fibroids. At follow-up, 12 (92.3%) of the 13 patients reported significant improvement in presenting symptoms and quality of life. One patient continued experiencing menorrhagia, and one patient experienced amenorrhea during the 5 months of follow-up after embolization. MR imaging in nine patients, performed at a mean of 5.9 months after embolization, revealed significant reductions in median uterine volume (42%), median fibroid volume (71%), and mean-junctional-zone thickness (11 mm; 33%; p < 0.5). Six of the nine patients had subendometrial regions of decreased T2 signal intensity after embolization. CONCLUSION: Uterine artery embolization is a promising nonsurgical alternative for patients with menorrhagia and adenomyosis. Significant improvement in presenting symptoms and in quality of life is associated with decreases in uterine size and junctional zone thickness. Larger prospective studies are needed to establish the safety and efficacy of this procedure for patients with adenomyosis.

Arteries↗
PubMed2000

Understanding the Doppler RI: impact of renal arterial distensibility on the RI in a hydronephrotic ex vivo rabbit kidney model.

The aim of this study was to evaluate the influence of elevated ureteral pressure on renal arterial distention, and thereby on the Doppler resistive index. Seven isolated rabbit kidneys were subjected to a pulsatile perfusion while the renal pelvis was pressurized via the ureter. Renal vascular pressure, flow, resistance (pressure/flow) and conductance (flow/pressure) were compared to simultaneous resistive index measurements using linear regression analysis. Changes in the Conductance Index (systolic conductance - diastolic conductance/systolic conductance) were likewise compared to the resistive index. Elevations in ureteral pressure were significantly correlated with (1) increased resistive index values, (2) increased mean renal vascular resistance, (3) decreased mean conductance, and (4) increased conductance index values (for all correlations P < 0.05). The increases in the resistive index correlated significantly with increases in the conductance index. This study shows that elevated ureteral pressure, likely acting via interstitial pressure, diminishes the conductance of the renal vascular bed. Because this effect is more dramatic at diastole, the cyclic patterns of flow are altered, resulting in elevated resistive index values. The results indicate the importance of the interaction between vascular distensibility and pulsatile flow, rather than overall mean renal vascular resistance, in determining resistive index values.

Animals↗
PubMed1999

Effect of injection rate of contrast medium on pancreatic and hepatic helical CT.

PURPOSE: To assess the effect of the injection rate of contrast medium on pancreatic and hepatic enhancement at abdominal helical computed tomography (CT). MATERIALS AND METHODS: Sixty-four contrast medium-enhanced abdominal helical CT scans (64 adult patients) were obtained with 150 mL of contrast medium. The injection rate was 2.5 mL/sec for the first 32 scans and 5.0 mL/sec for the remaining 32. Scans were obtained at 5-sec intervals, with an intermediate 8-sec breathing interval. Hepatic and pancreatic enhancement levels were measured and averaged, and time-attenuation curves were plotted for both groups. Differences in weight, age, time to peak pancreatic and hepatic enhancement, and peak enhancement were assessed with the Student t test. RESULTS: Both peak enhancement and time to peak enhancement were significantly different between the two injection rates (P < or = .002), with faster, more intense hepatic and pancreatic enhancement at the higher rate. At 2.5 mL/sec, the pancreas reached a peak attenuation level of 65 HU at 69 sec, and the liver reached a peak of 58 HU at 87 sec. At 5.0 mL/sec, the pancreas reached a peak attenuation of 84 HU at 43 sec, and the liver reached a peak of 75 HU at 63 sec.

Adult↗
PubMed1999

Correlation between renal vascular resistance, pulse pressure, and the resistive index in isolated perfused rabbit kidneys.

PURPOSE: To assess the effect of acute changes in renal vascular resistance (RVR) and pulse pressure on the resistive index (RI) measured by using Doppler ultrasonography (US). MATERIALS AND METHODS: Rabbit kidneys were perfused by using a pulsatile perfusion system in which RVR, systolic and diastolic pulse pressures, and pulse kinetics were controlled and monitored while simultaneously measuring the RI. RESULTS: When RVR was increased fivefold with phenylephrine hydrochloride, the RI increased only slightly (from 0.45 at baseline up to 0.50). There was a virtually linear relationship between the RI and the pulse pressure index ([systolic pressure-diastolic pressure]/systolic pressure) in the range of 0.30-0.80. The RI was not affected by the pulse rate or fraction of time that systolic pressure was applied during the pulse cycle. CONCLUSION: Contrary to conventional teaching, which is based on theoretic considerations, the RI is not readily affected by acute changes in RVR. This indicates a need to reconsider the conventional explanations used to explain increases in RI that are frequently found in patients with renal disease or ureteral obstruction.

Animals↗
PubMed1999

Blood flow in healthy gallbladder walls on color and power Doppler sonography: effect of wall thickness and gallbladder volume.

OBJECTIVE: The purpose of this study was to determine the effect of gallbladder contraction on the conspicuity of flow in the normal gallbladder wall. SUBJECTS AND METHODS: Ten healthy adult volunteers without clinical evidence of gallbladder disease participated in the study. After patients fasted overnight, the gallbladder was scanned using gray-scale, color Doppler, and power Doppler sonography. The subjects were then given a standard meal consisting of 478 ml of a carbohydrate-rich dietary supplement, and the imaging sequence was repeated 20 and 45 min thereafter. Mural flow was graded using a four-step grading scheme. Gallbladder volume, wall thickness, and visibility of mural flow at all three time points were statistically compared. RESULTS: Enhanced mural flow was seen after meal consumption in all but one volunteer. Overall, mural flow was significantly greater 45 min after eating than at baseline or 20 min on color Doppler sonography (p = .004) and power Doppler sonography (p = .008). CONCLUSION: Flow in the gallbladder wall is a normal finding that is seen more easily when the gallbladder is contracted. This fact must be kept in mind when sonography is used with patients in whom acute cholecystitis is suspected, particularly if they do not fast before sonography.

Adult↗
PubMed1998

Influence of contrast media on the response of rat renal arteries to endothelin and nitric oxide: influence of contrast media.

RATIONALE AND OBJECTIVES: Contrast media (CM) such as diatrizoate meglumine (DTZ) or iohexol can cause renal vasoconstriction in vivo, and this may initiate CM-induced nephropathy. Endothelin-1 (ET-1), a vasoconstrictor, and nitric oxide, a vasodilator, are key modulators of renal circulation. We tested the hypothesis that CM enhances arterial responses to ET-1, or diminishes responses to nitric oxide. METHODS: A video dimension analyzer continuously recorded changes in diameter of isolated, pressurized rat interlobar renal arteries (200-400 microm diameter) superfused with combinations of CM, ET-1, nitric oxide, and other vasoactive agents. RESULTS: Superfusion of arteries with 3.3% DTZ, but not with 3.3% iohexol, enhanced their sensitivity to ET-1 by approximately twofold, as assessed by shifts in concentration-response curves. Both DTZ and iohexol decreased the sensitivity of arteries to nitric oxide by approximately threefold. Neither DTZ nor iohexol affected arterial sensitivity to other vasoconstrictors (phenylephrine, potassium) or vasodilators (forskolin, diltiazem). CONCLUSIONS: Diatrizoate meglumine and iohexol may induce or augment renal vasoconstriction in part by causing selective alterations in arterial sensitivity to ET-1 and to nitric oxide.

Analysis of Variance↗
PubMed1997

Cardiopulmonary thromboembolism detected by Tc-99m MH-1 antifibrin antibody.

A patient with shortness of breath had a high probability lung scan for pulmonary embolism, but no obvious embolic source. Whole-body scintigraphy using Tc-99m labeled Fab' antifibrin monoclonal antibody showed large central pulmonary emboli as well as tracer uptake in the right atrium and aortic arch. No lower extremity clot was detected. This case shows significant differences in the appearance of pulmonary embolism as assessed by direct clot and ventilation-perfusion scintigraphy. It shows the importance of the heart as the origin of pulmonary emboli and the utility of direct thrombus visualization.

Aged↗
PubMed1997

Effect of hydration status on renal medulla attenuation on unenhanced CT scans.

OBJECTIVE: The purpose of this study was to assess the effect of hydration status on renal medulla attenuation during unenhanced CT. SUBJECTS AND METHODS: An unenhanced CT scan was obtained in 10 healthy men after 12-18 hr of complete fluid restriction and again after rehydration. CT images were reviewed for the presence and extent of dense renal medulla, defined as greater attenuation than the adjacent cortex. CT findings were correlated with urine-specific gravity and osmolality. RESULTS: Eight of the 10 subjects showed dense renal medulla on a CT scan after dehydration. After rehydration, complete resolution was seen on the CT scan in four of the eight subjects; three of the eight subjects showed a decrease in the extent of dense renal medulla. After rehydration, the eighth subject showed a slight increase in the attenuation of the renal medulla on the CT scan. Dense renal medulla was seen significantly more often on dehydration images (p = .035). CONCLUSION: Increased renal medulla attenuation on an unenhanced CT scan can be a normal finding related to dehydration.

Adult↗
PubMed1997

Benign and malignant portal vein thrombosis: differentiation by CT characteristics.

OBJECTIVE: The purpose of this study was to determine if unique characteristics revealed by CT can allow radiologists to reliably distinguish benign from malignant portal vein thrombus (PVT) in patients with cirrhosis. MATERIALS AND METHODS: CT examinations of 58 patients with cirrhosis and PVT were retrospectively reviewed. Images were assessed for location, extent, enhancement, neovascularity, and maximal diameter of PVT. The type of PVT was proven histologically in 42 patients and clinically in the remaining 16 patients. Using different threshold PVT diameters or the presence of PVT neovascularity, we calculated the sensitivity and specificity of CT for revealing malignant PVT. RESULTS: Forty-seven patients had malignant and 11 patients had benign PVT. CT scans of patients with malignant PVT showed direct extension of hepatocellular carcinoma into the portal vein in 15 patients. In 29 patients with malignant PVT, CT scans showed PVT adjacent to tumor; CT scans showed tumor PVT remote from hepatocellular carcinoma in the remaining three patients with malignant PVT. The mean diameters of malignant and benign portal vein thrombi were significantly different (23.4 mm versus 16 mm; p = .0001). CT scans of 83% (39/47) of patients with malignant PVT and 18% (2/11) of patients with benign PVT showed generalized enhancement. Neovascularity was seen on CT scans in 43% (20/47) of patients with malignant PVT and in no patient with benign PVT. Identification of a main PVT diameter greater than or equal to 23 mm or PVT neovascularity resulted in a sensitivity and specificity for the CT characterization of malignant PVT of 86% and 100%, respectively. CONCLUSION: Malignant and benign thrombi can often be differentiated by radiologists on the basis of CT imaging characteristics.

Carcinoma, Hepatocellular↗
PubMed1996

Ultrasound assessment of testicular and paratesticular masses.

This article discusses the role of ultrasound in the workup of patients with suspected or palpable scrotal masses. By characterizing masses as intra- or extratesticular, the differential diagnosis can be narrowed considerably. Neoplasm is the primary concern with intratesticular masses, although non-neoplastic conditions, such as hematoma and focal orchitis, may have a similar appearance. Correlation with the patient's history is essential. The sonographic presentation of extratesticular pathology, including varicocele and masses of epididymal origin, is also described.

Diagnosis, Differential↗
PubMed1996

Value of selective second-look sonography by radiologists.

PURPOSE: To assess the usefulness of sonography performed by radiologists after a review of the sonographer's findings. MATERIALS AND METHODS: A total of 398 sonograms were obtained in 392 patients. Sonographers presented preliminary images and impressions to radiologists, who performed additional imaging and recorded their conclusions. Radiologists also attempted to predict in which cases their scan was likely to show new findings or to refute the sonographer's findings. Follow-up data were obtained whenever the sonographer's and the radiologist's findings disagreed. RESULTS: In 28 cases, the radiologist made important new findings. Positive initial findings were refuted in 24 cases. Discrepant findings were seen in 22% of cases in which additional scanning was predicted to be beneficial, compared with only 6% of cases in which second-look sonography was predicted not to be of value. This difference was statistically significant (P<.0001). CONCLUSION: Second-look sonography by radiologists provides a valuable check of the sonographer's findings.

Diagnostic Errors↗
PubMed1995

Role of the resistive index in the evaluation of acute renal obstruction.

Sonography is well established as a screening tool to evaluate the kidney for the presence of renal obstruction. The role of sonography in the evaluation of acute obstruction is less clear, however. Despite recent reports emphasizing the ability of gray-scale sonography and kidney/urinary/bladder films to screen for acute colic, experience indicates that the sonographic diagnosis of acute renal stone disease may be unreliable. Multiple studies have demonstrated the many potential pitfalls of the sonographic examination for acute obstruction. False-negative studies may result if the kidney is evaluated before hydronephrosis occurs. Conversely, nonobstructive pyelocaliectasis and parapelvic cysts may result in false-positive studies. Because of these sonographic limitations, many imaging practices exclusively have utilized excretory urography for the evaluation of patients with symptoms of renal colic.

Acute Disease↗
PubMed1995

Sonography of renal transplantation.

Marked improvements in graft survival have made renal transplantation the treatment of choice for end-stage renal disease. Ultrasound, because it is an accurate and noninvasive screening examination for graft dysfunction, clearly has had an impact upon graft survival rates. Gray scale sonography easily detects hydronephrosis and perinephric fluid collections. Vascular complications of transplantation--AVFs, pseudoaneurysms, arterial/venous thrombosis and stenosis--are readily identified by color and duplex Doppler sonography. Initial enthusiasm for the gray scale and Doppler identification of acute rejection largely has been proved to be unfounded. Ultrasound guidance, however, clearly minimizes the risk and discomfort of definitive percutaneous renal transplant biopsy.

Humans↗
PubMed1994

Acute renal colic: diagnosis with duplex Doppler US.

PURPOSE: To determine the sensitivity of renal duplex Doppler sonography in the detection of patients with acute renal colic. MATERIALS AND METHODS: The authors correlated results of renal duplex Doppler sonography with those of urography in 32 patients presenting with symptoms of urinary colic. The mean resistive index (RI) of each kidney and the difference between the mean RIs (delta RI) of both kidneys were calculated for all patients. The nonpaired two-tailed Student t test was used to determine if there was a significant difference in parameters between patients with and without obstruction. The sensitivity and specificity of the mean RI and the delta RI for the diagnosis of acute renal colic were calculated. RESULTS: Nineteen patients had obstruction. The differences in the mean RI and delta RI for the patients with and without obstruction were statistically significant. When the published discriminatory thresholds for obstruction (mean RI > or = 0.7, delta RI > or = 0.1) were applied, however, the sensitivity and specificity of the Doppler examination were only 44% and 82%, respectively. CONCLUSION: Duplex Doppler sonography is highly insensitive for the detection of acute renal colic.

Acute Disease↗
PubMed1991

Imaging of vascular complications associated with renal transplants.

Vascular complications associated with renal transplants are a significant cause of graft dysfunction. The most common complications are arterial and venous stenoses and thromboses and intrarenal and extrarenal arteriovenous fistulas and pseudoaneurysms. Although angiography is the imaging gold standard for the diagnosis of these disorders, Doppler sonography, scintigraphy, and occasionally CT are capable of detecting them. An awareness of the different imaging appearances of each complication will aid in their early detection and treatment. In this review, we present this information and provide a perspective on the relative roles of these techniques in the detection of vascular complications from renal transplants.

Diagnostic Imaging↗