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Biomedical subjects

J M Rubin

Publications and source records attributed to J M Rubin.

At least 127 records · Page 7Linked to original sources
PubMed1989

Duplex Doppler US of the kidney: differentiation of obstructive from nonobstructive dilatation.

Distinction of the obstructed from the nonobstructed dilated renal collecting system is a difficult problem often requiring interventional procedures and pressure measurements. The authors prospectively performed duplex Doppler ultrasound (US) evaluations in 21 kidneys (obstructed, n = 14; nonobstructed, n = 7) immediately before percutaneous nephrostomy. In addition, ten of the obstructed kidneys were evaluated with follow-up Doppler US after percutaneous nephrostomy. Renal obstruction caused a change in the Doppler waveform detected by means of the resistive index (RI). Thirteen of the 14 obstructed kidneys had a RI value greater than .70, while none of the nonobstructed kidneys had a RI value exceeding .70. Relief of the obstruction resulted in a reduced RI; in nine of ten kidneys, the RI was less than or equal to .70 (similar to that of the nonobstructed kidneys). When a dilated collecting system is being imaged, additional evaluation with duplex Doppler US may help distinguish obstructed from nonobstructed dilatation, which may be of particular benefit in patients with conditions that usually predispose them to collecting system dilatation.

Diagnosis, Differential↗
PubMed1989

Distinction between obstructive and nonobstructive pyelocaliectasis with duplex Doppler sonography.

Because animal studies have shown that renal obstruction increases renal vascular resistance, we theorized that obstruction would change the Doppler waveform. We studied the value of the resistive index (RI) calculated from the duplex Doppler waveform to distinguish between obstructive and nonobstructive pyelocaliectasis in 229 kidneys in 133 patients. The RI is the peak systolic frequency shift minus the minimum diastolic frequency shift, then divided by the peak systolic frequency shift. Duplex Doppler sonography was performed prospectively in 70 kidneys with pyelocaliectasis before the presence or absence of obstruction was established. In 54 of 70 kidneys, the presence or absence of obstruction was proved by interventional methods (percutaneous nephrostomy, antegrade or retrograde pyelography, loopography), and in the rest it was proved by body CT, excretory urography, or surgery. Thirty-eight kidneys were found to be obstructed, and 32 had nonobstructive dilatation. In addition, 159 kidneys without pyelocaliectasis were studied to identify possible limitations of Doppler sonography in the diagnosis of obstruction. Clinical history and laboratory data were used to determine that 109 of these kidneys were in normal subjects and 50 were in patients with nondilated renal disease. There was a significant difference between the mean RI of the obstructed (0.77 +/- 0.05) and the nonobstructed dilated (0.63 +/- 0.06) kidneys (p less than .01). Analysis of the receiver-operating-characteristic curve showed an RI of 0.70 to be a good discriminatory level for obstruction, resulting in a sensitivity of 92%, a specificity of 88%, and an accuracy of 90%. All 109 normal kidneys had an RI less than 0.70. Over half (27/50) of the kidneys in patients with nondilated renal disease had an elevated RI (greater than or equal to 0.70). Ninety-six patients had Doppler examinations on both kidneys, and in only six patients did the RI values of each kidney differ by more than 0.10; all six were proved to have unilateral obstruction. Use of duplex Doppler sonography should improve the specificity, and thus the accuracy, of sonography in the noninvasive diagnosis of obstruction and should be used when a dilated collecting system is identified.

Adolescent↗
PubMed1989

Intraoperative sonography in low-grade gliomas.

A retrospective study of intraoperative sonography and preoperative head computed tomography (CT) in 15 patients with low-grade brain gliomas was undertaken to determine whether areas of increased echogenicity without shadowing corresponded with areas of pathologic CT enhancement. Glioma echogenicity was considered increased if greater than or equal to adjacent sulcal echogenicity. Of the 15 lesions, 7 of 8 with pathologic CT enhancement showed areas of increased echogenicity without shadowing. Areas of increased echogenicity topographically correlated with areas of pathologic CT enhancement. One of eight lesions with pathologic enhancement had no areas of increased echogenicity; however, the enhancement in this lesion was minimal. Six of seven patients without pathologic CT enhancement had areas of echogenicity always less than sulcal echogenicity. Our results suggest that, in low-grade gliomas, regions of enhancement usually correspond to areas of increased echogenicity without shadowing. These findings differ from those found with high-grade gliomas.

Astrocytoma↗
PubMed1988

Anisotropic ultrasonic backscatter from the renal cortex.

We have demonstrated a significant, directionally dependent, anisotropic, echogenicity from the cortices of two sheep kidneys and a normal human cadaver kidney. The anisotropy corresponds to the relationship of the sound field to the medullary rays and interlobular arteries. At 7.5 MHz, the backscatter from specimens of cortex of a sheep kidney was 4.7 +/- .7 dB (mean +/- SEM) greater in parts of the cortex where the field was perpendicular to these structures as opposed to where it was parallel to them. In addition, we measured the angular distribution of this anisotropy and compared it to the 5 dB inclusion angle of the 5 MHz linear array that was used in measurements on the whole kidney specimens. The transducer inclusion angle was 10 degrees +/- 2 degrees, while the angular distribution was 34 degrees +/- 22 degrees and 23 degrees +/- 11 degrees (mean +/- SD) for the intact sheep and human kidney, respectively, demonstrating some variation of the medullary rays from perfect specular reflectors. This anisotropy should be visible in standard diagnostic scanning, and its recognition could increase ultrasound's sensitivity for the detection of renal disease.

Animals↗
PubMed1988

Vascular patency of fibular free graft: assessment by Doppler color-flow imager: a case report.

Viability of a vascularized free fibula transfer can be difficult to establish. It is possible, however, to assess patency of the involved microvascular anastomoses and blood flow in the vessels of the transposed fibula. A Doppler color-flow imager can be used to evaluate blood flow and vascular patency. The imager potentially can be employed in the operating room, during the immediate postoperative period, and for long term follow-up. It is non-invasive and produces a permanent record of vascular anatomy and flow characteristics.

Adolescent↗
PubMed1988

The distinction between femoral artery pseudoaneurysms and other causes of groin masses: value of duplex Doppler sonography.

With the increasing use of percutaneous transfemoral coronary angioplasty in conjunction with thrombolytic as well as anticoagulant therapy, the sonographic evaluation of groin masses, with particular emphasis on differentiating pseudoaneurysms from hematomas and other abnormalities, has become more common. Seventy-three sonograms of the groin in 60 patients (65 different groins) were reviewed retrospectively to determine the accuracy of duplex Doppler sonography in distinguishing femoral artery pseudoaneurysm (a surgical condition) from other causes of groin masses (e.g., hematomas) that are generally treated conservatively. Nineteen cases of pseudoaneurysm, 19 cases of hematoma, and 27 other conditions were studied. Of the 73 sonograms performed, 53 included duplex Doppler studies; one Doppler study was false-negative and two were possibly false-positive. The sensitivity, specificity, and accuracy of duplex Doppler sonography in the detection of femoral artery pseudoaneurysm was 95 +/- 5.8%, 94 +/- 6.4%, and 94 +/- 6.4%, respectively (95% confidence limit). We conclude that duplex Doppler sonography is of value in the differential diagnosis of groin masses.

Adult↗
PubMed1988

The inability to detect kidney disease on the basis of echogenicity.

With the use of new sonographic technology, we have observed that the echogenicity of kidneys is often equal to that of the liver in patients in whom there is no evidence of renal disease; this observation conflicts with the generally accepted notion that a normal kidney is always less echogenic than the liver. In order to reassess renal echogenicity as an indicator of disease, three experienced radiologists blindly reviewed the sonograms of the right kidney and liver in 153 patients. The prevalence of renal disease was 26% (40/153). Accepted sonographic criteria for abnormal renal echogenicity (kidney echogenicity greater than or equal to liver) were neither sensitive (62%) nor specific (58%) for renal disease, with a positive predictive value of 35%. Most of these inaccuracies occurred because 43 (72%) of 60 patients in whom renal echogenicity was equal to that of liver had normal renal function. If stricter criteria for abnormality were adopted (kidney echogenicity greater than liver), specificity (96%) and positive predictive value (67%) rose; however, sensitivity was only 20%. We conclude that renal echogenicity equal to the echogenicity of liver is not a good indicator of disease. Use of stricter criteria (kidney echogenicity greater than liver) provides a specific but insensitive test.

Adult↗
PubMed1988

Intraoperative color-flow Doppler imaging of AVM's and aneurysms.

The use of intraoperative color-flow Doppler sonography to image cerebral and spinal arteriovenous malformations (AVM's) and a giant aneurysm is reported in 10 patients. The technique is a useful adjunct in localizing vascular lesions, identifying feeding or draining vessels, and confirming intraoperative surgical excision of AVM's or ligation of giant aneurysms. Imaging of lesions deeper than 4 to 5 cm is, however, limited with the equipment design now commercially available.

Adult↗
PubMed1988

Intraoperative spinal sonography in the evaluation of intramedullary tumors.

Seventeen intraoperative spinal sonographic examinations were performed in 14 patients with intramedullary spinal cord neoplasms. Results of the ultrasound exams were correlated with preoperative imaging studies, surgical findings, and histopathologic analysis of the tumors. Intraoperative spinal sonography accurately localized the intramedullary tumors, often revealing the need for extension of the initial laminectomy. The neoplasms appeared as expansile echogenic masses, with cystic components in over half. Ultrasound was as accurate as preoperative imaging in the evaluation of solid neoplasms, and was superior to computed tomography (CT) and magnetic resonance imaging (MRI) for delineating the cystic components of neoplasms. Intraoperative sonography should be used routinely in all surgical cases of intramedullary spinal cord neoplasms.

Adolescent↗
PubMed1988

Spinal ultrasonography. Intraoperative and pediatric applications.

Ultrasonography has had limited usefulness in the diagnosis of diseases of the spine and spinal cord in older children and adults. However, its use intraoperatively in patients of all ages, and nonoperatively in infants and young children, is finding increased application. The authors, who perform and rely on spinal sonography in both clinical situations, present an overview of technique, normal anatomy, and selected pathologic entities based on their experience and the literature.

Child, Preschool↗
PubMed1988

Cervical spondylosis and syringomyelia: suboptimal results, incomplete treatment, and the role of intraoperative ultrasound.

The pathophysiology of cervical spondylotic myelopathy and syringomyelia is incompletely understood. Only 50-60% of the former group of patients and only 30-40% of the latter group of patients show long-term improvement. One possible cause for this might be continued anterior compression of the spinal cord in the former and incomplete drainage of the fluid-filled cavities in the latter. Intraoperative ultrasound imaging can be done in the operating room (4-6, 16-18) and can identify whether an adequate decompression has been done in patients with cervical spondylotic myelopathy and whether there has been complete drainage in shunting of patients with syringomyelia. Intraoperative ultrasound imaging aids the neurosurgeon in checking to see if he did what he set out to do. It is useful in operative procedures for cervical spondylotic myelopathy and syringomyelia.

Cervical Vertebrae↗
PubMed1987

Porta hepatis: duplex Doppler US with angiographic correlation.

Duplex Doppler ultrasonography (US) and panhepatic angiography were performed and interpreted independently in 20 patients with suspected portal hypertension to assess the accuracy of duplex US in the porta hepatis. Hepatic arterial resistive indexes were correlated with corrected sinusoidal pressures. The results of duplex US agreed with those of angiography in 16 patients with a normal portal vein (including three with hepatofugal flow) and two with total thrombosis. One angiographically normal portal vein appeared thrombosed on an initial sonogram, but a second scan was normal. One case of partial thrombosis was not diagnosed with duplex US. Sensitivity and specificity for main portal vein disorders were 83% and 93%, respectively. Two patients had portal vein branch occlusions that were found by angiography but not by US. Portal vein echogenicity was neither sensitive nor specific for thrombosis. The resistive index of the hepatic artery was specific for portal hypertension when above .78, but it was not sensitive. Duplex US is accurate in prospectively assessing the direction of flow and the presence of total thrombosis in the portal vein, but partial thrombosis may not be detected on sonograms.

Adolescent↗
PubMed1987

Sonographic parallel channel sign: a reappraisal.

Tubular structures proximal to the right and left hepatic ducts, when seen with ultrasonography, are generally considered to be abnormally dilated ducts. However, newer, electronically focused transducers reveal peripheral tubular structures paralleling portal venous branches. The diameters of all visible tubular structures that would have been thought to be bile ducts were measured in 50 persons with no evidence of hepatobiliary disease. "Ducts" were seen with the following frequencies: right hepatic, 100%; right anterior, 100%; right posterior, 88%; left hepatic, 98%; left medial, 62%; left lateral, 96%; left lateral superior, 54%; and left lateral inferior, 54%. All ducts proximal to the right and left hepatic ducts were 2 mm or less in diameter. Those proximal to the common hepatic ducts averaged approximately 20% of the diameters of their accompanying portal veins. Except for 4% of the left lateral inferior ducts, no ducts proximal to the common hepatic ducts were more than 40% the diameter of their respective portal vein branches. Mere observation of parallel channels proximal to the right and left hepatic ducts is therefore not evidence of biliary dilatation.

Adult↗