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Biomedical subjects

W D Middleton

Publications and source records attributed to W D Middleton.

At least 73 records · Page 4Linked to original sources
PubMed1989

Color Doppler evaluation of arterial stenoses and occlusions involving the neck and thoracic inlet.

Color Doppler flow imaging is a new technique providing simultaneous display of a gray-scale tissue and a color-flow vascular image. We demonstrate its ability to predict accurately occlusions of numerous vessels, including the internal carotid, external carotid, common carotid, subclavian and innominate arteries. Alterations in flow direction and changes in spectral wave form provide useful clues to the presence of these occlusions. The cases are correlated with angiographic findings and functional flow diagrams of the hemodynamic changes involved.

Arterial Occlusive Diseases↗
PubMed1989

Iatrogenic femoral arteriovenous fistula: diagnosis with color Doppler imaging.

Color Doppler imaging was used to identify and localize arteriovenous fistulas in six patients after cardiac catheterization. In all six, there was a focal region of persistent intraarterial flow throughout the cardiac cycle at the site of the fistula, in contrast to normal arterial flow, which is forward only in systole. In all cases, turbulent pulsatile venous flow was present at the site of the fistula and nonturbulent pulsatile venous flow was present proximal to the fistula. In five cases a focal area of apparent extravascular tissue vibration was identified. In four cases the communication between the artery and vein was identified. Familiarity with these color Doppler imaging findings should allow for accurate noninvasive diagnosis of arteriovenous fistulas, at the patient's beside if necessary.

Arteriovenous Fistula↗
PubMed1989

Postbiopsy renal transplant arteriovenous fistulas: color Doppler US characteristics.

Color Doppler ultrasound (US) with point-spectral analysis was performed on eight patients with postbiopsy renal transplant arteriovenous fistulas. Waveform analysis of the supplying artery documented decreased resistive indices in all cases and increased flow velocities in seven. The peak-systolic flow velocity in the arteries supplying the fistulas ranged from 55 to 180 cm/sec (mean, 92 cm/sec), while the range in normal arteries was 20-52 cm/sec (mean, 32 cm/sec). The resistive indices of the arteries supplying the fistulas ranged from 0.31 to 0.50 (mean, 0.45), while the resistive indices of the normal arteries ranged from 0.60 to 0.92 (mean, 0.74). Arterialization of the venous waveform from the draining vein was also documented in all cases. In six cases, the increased flow velocities resulted in increased color saturation toward white in the supplying artery (n = 2) or in both the artery and the draining vein (n = 4), which was detectable on the realtime image. In six cases, flow turbulence resulted in localized tissue vibration, which appeared as random color assignment in extravascular renal parenchyma adjacent to the fistula. Knowledge of these imaging and Doppler characteristics should aid in the identification of renal transplant arteriovenous fistulas with color Doppler US.

Arteriovenous Fistula↗
PubMed1989

Perivascular color artifact: pathologic significance and appearance on color Doppler US images.

A distinctive type of artifactual extravascular assignment of color was identified in 49 color Doppler ultrasound (US) examinations in 43 patients. This artifact appeared as a random localized mixture of red and blue assigned to perivascular soft tissues; the artifact varied with the cardiac cycle, being most prominent in systole and absent or less prominent in diastole. The artifact was seen in 26 patients (32 examinations) at an anastomotic site or stenotic lesion associated with surgically created arteriovenous fistulas for hemodialysis. It was also observed in ten patients with accidental iatrogenic arteriovenous fistulas (renal transplant [n = 6], femoral artery [n = 3], and iliac artery [n = 1]), five with stenotic arteries not associated with arteriovenous fistulas, and two with arterial aneurysms. The authors believe this artifact reflects perivascular tissue vibration caused by turbulent intravascular blood flow. If properly recognized and accurately interpreted, the artifact can be a valuable color Doppler US sign of underlying vascular abnormality.

Aneurysm↗
PubMed1989

Renal duplication artifact in US imaging.

To determine the appearance of artifactual renal duplication in ultrasound (US) imaging, the authors analyzed 22 examples of such duplication in 20 patients. The artifact appeared as a duplication of the collecting system in 18, as a suprarenal mass in three, and as upper-pole cortical thickening in one. It occurred in the left kidney in 15 patients, in the right kidney in three, and bilaterally in two. To determine the frequency of the artifact, 50 additional patients were scanned. It was identified in eight of these patients. Imaging characteristics and the results of in vitro modeling proved the artifact was due to sound beam refraction between the lower pole of the spleen or liver and adjacent fat. This artifact is much more common in the left kidney and occurs more frequently in obese patients. Knowledge of the appearance and cause of this artifact should help radiologists avoid diagnostic errors.

Diagnostic Errors↗
PubMed1989

Inability of sonography to detect imminent ovulation.

Sonographic visualization of the cumulus oophorus or of morphologic alterations in the wall of the dominant follicle have been reported to be reliable signs of imminent ovulation when conventional transabdominal sonography is used. To determine if transvaginal sonography could allow a more frequent and confident prediction of imminent ovulation, we prospectively monitored 22 ovulatory menstrual cycles in four women undergoing artificial insemination and in 13 normally menstruating volunteers. Scanning was done on alternate days in the periovulatory period; a 7.5-MHz transvaginal transducer was used. Despite the improved resolution obtained with transvaginal sonography, confident identification of the cumulus oophorus or of mural changes in the follicle was not possible in any of the cycles followed. No other consistent follicular characteristic predicted imminent ovulation. We conclude that confident prediction of imminent ovulation is not possible with sonographic analysis.

Adult↗
PubMed1989

Color Doppler ultrasound of the normal testis.

Color Doppler ultrasound with point spectral analysis was performed on 30 testes of 15 asymptomatic volunteers. Intratesticular arteries and testicular capsular arteries were imaged in all 30 cases. Waveforms from these vessels were similar and consistently showed a low-impedance pattern with high levels of diastolic flow. This reflects the low vascular resistance of the testis. Supratesticular arteries were also identified in all 30 cases. In addition to the low-impedance-type waveforms from the testicular artery, waveforms obtained in the supratesticular region also originated from the deferential and/or cremasteric arteries. This resulted in some waveforms with high-impedance patterns, reflecting the high vascular resistance of the epididymis and peritesticular tissues. We believe that color Doppler ultrasound is capable of reliably showing the normal testicular arterial anatomy by imaging intraarterial blood flow. Knowledge of the normal color Doppler appearance and waveform characteristics of the testicular artery should aid in diagnosing scrotal conditions that alter blood flow.

Adult↗
PubMed1989

Color Doppler ultrasound imaging of lower-extremity venous disease.

A color Doppler ultrasound imaging device was used to evaluate 475 patients with suspected lower-extremity venous thrombosis. Occlusive and nonocclusive femoral and popliteal thrombi were detected in 200 studies (42%). In phase 1 of the study (240 examinations), peripheral augmentation with the use of periodic calf compression was required to show color flow throughout the femoropopliteal venous segment. In phase 2 (235 examinations), with a software upgrade to enhance detectability of slow flow, spontaneous flow could be appreciated in the normal, partly thrombosed, and recanalized femoral popliteal veins without augmentation. Augmentation was often necessary to view tibioperoneal veins. Of the total study group, conventional venography was performed for correlation in 47 patients. In the other patients, clinicians relied on the color Doppler test for the definitive diagnosis of the presence or absence of femoral popliteal venous thrombosis and treated these patients on the basis of the color Doppler test result. In the femoral veins, color Doppler studies and venography agreed in all 12 positive and 35 negative cases. In the popliteal veins, there was agreement in five isolated popliteal thromboses and in 10 femoral popliteal thromboses; there were two false-negative color Doppler studies of isolated popliteal thromboses. In four patients, Doppler studies detected nonocclusive thrombus not evident on venography. Color Doppler imaging is easy to perform and does not require augmentation to view color flow in the femoropopliteal venous segment. Eccentric thrombus and partially canalized thrombus can be shown. Initial experience suggests color Doppler imaging may be useful in the detection of tibioperoneal venous thrombosis.

Femoral Vein↗
PubMed1989

Color Doppler sonography of hemodialysis vascular access: comparison with angiography.

This study was performed to define the color Doppler sonographic appearance of normal and abnormal hemodialysis vascular access and to compare color Doppler sonography with angiography. Twenty-eight patients (nine with Brescia-Cimino fistulas and 19 with synthetic grafts) were imaged with digital subtraction angiography and color Doppler sonography. The examinations were interpreted independently and then interpreted together to determine the accuracy of the two methods. With angiography as the gold standard, color Doppler sonography correctly identified 20 of 23 stenosed vessels, three of four occluded vessels, four of four thrombosed vessels, and 18 of 19 pseudoaneurysms. Overall, color Doppler sonography correctly identified all lesions that were seen angiographically in 16 of 19 patients with synthetic grafts and in four of nine patients with Brescia-Cimino fistulas. Five asymptomatic arterial steals were detected sonographically. One of these was identified with angiography. Color Doppler sonography is an adequate means of imaging suspected complications of hemodialysis vascular access, and it should be used in selected patients. However, digital subtraction angiography is more sensitive and should be the initial imaging technique for most of these patients.

Adult↗
PubMed1989

Testicular ischemia: color Doppler sonographic findings in five patients.

We studied the findings on color Doppler sonography in five men with testicular ischemia (three with acute testicular torsion and two with testicular infarcts after herniorrhaphies). In all five cases, no intratesticular blood flow was identified on the symptomatic side, while normal blood flow was evident on the opposite side. In the three cases of acute torsion, no gray scale sonographic abnormalities were seen, and in the two cases of postoperative infarction, the abnormalities were nonspecific. These findings suggest that color Doppler sonography can be used to show decreased blood flow in cases of acute testicular ischemia and that it may have a role in evaluating patients with suspected testicular torsion.

Adult↗
PubMed1989

Stenosis of the internal carotid artery: assessment using color Doppler imaging compared with angiography.

The percentage of diameter stenosis of the internal carotid artery was estimated directly from color Doppler images obtained in both longitudinal and transverse planes and compared with the results of digital subtraction angiography in 49 patients (95 carotid arteries). Peak systolic velocity measurements were obtained by placing the sample volume in the highest-velocity flow stream with the angle-correction cursor parallel to the color-encoded lumen. Arterial stenoses were categorized on a grade 1-5 scale: 1 = 0-15%, 2 = 16-49%, 3 = 50-75%, 4 = 76-99%, and 5 = occlusion. Percent diameter stenosis could not be determined in 12 color Doppler flow imaging studies (13%) due to calcified plaque. Of the remaining 83 arteries evaluated by both techniques, the respective categories by color Doppler flow imaging/angiography were grade 1 (16/26), grade 2 (25/24), grade 3 (30/19), grade 4 (5/8), and grade 5 (7/6). Percent diameter stenosis determined by color Doppler flow imaging was greater than by angiography in 25% and less than by angiography in 4%. Peak systolic velocity measurements did not separate the hemodynamically insignificant (less than 50% diameter stenosis) grade 1 and grade 2 lesions, but were in agreement in 86% of grades 3-5 stenotic categories, as determined by measurements from the color Doppler flow image. A direct measurement of percent diameter stenosis from the color Doppler flow image was possible in 87% of cases. Peak systolic velocity provided correlative diagnostic information when assessing hemodynamically significant lesions.

Angiography↗
PubMed1988

Flow reversal in the normal carotid bifurcation: color Doppler flow imaging analysis.

One hundred carotid bifurcations in young asymptomatic volunteers were examined with color Doppler flow imaging in an attempt to determine the frequency, configuration, magnitude, and duration of flow reversal. Areas of flow reversal were identified in all but one bifurcation. Just proximal to the bifurcation, flow reversal was typically located peripherally, opposite the origin of the external carotid artery. Distal to the bifurcation, flow reversal in the internal carotid artery typically assumed a linear configuration in the center of the vessel, extending from the superficial to the deep wall. Variations of these patterns were common. On the average, flow reversal occupied 33% of the lumen of the carotid bulb and extended for a distance of 14 mm. The average duration of flow reversal was 22% of the total cardiac cycle, with reversal typically occurring at peak systole and being replaced by static blood during diastole. These findings indicate that flow reversal in the carotid bifurcation is a normal phenomenon with a variable configuration, magnitude, and duration.

Adult↗