Doppler quantitative measures by region to discriminate prostate cancer.

This study was conducted to assess if sonographic discrimination between healthy and cancerous prostate tissue might be improved using regional analysis of ultrasound (US) Doppler measures. A total of 39 subjects underwent 3-D Doppler sonography before radical prostatectomy. Cancer locations were identified from hematoxylin and eosin (H&E)-stained slides. Three prostate data volumes consisting of a frequency shift and power-mode Doppler US and whole mount histology images were spatially registered for each prostate, then divided into entirely 1 mL-sized regions of cancerous or noncancerous tissue. Each prostate was visually divided into a peripheral and a periurethral region within which US Doppler measures were calculated. Receiver operating characteristic (ROC) and simulated biopsy analyses within each prostate were performed. Mean speed in colored pixels (V), and speed-weighted pixel density (SWD) are good discriminators for prostate cancer in the periurethral and the peripheral regions, respectively. Using SWD in a simulated biopsy yields increased cancer detection in the peripheral region.

US artifacts: effects on out-of-plane us images reconstructed from three-dimensional data sets.

Three-dimensional volumetric data sets of stacked ultrasonographic (US) scans were obtained in vitro and in vivo to investigate the effect of common US artifacts on cross-sectional images reconstructed out-of-plane to the plane of acquisition of these data sets. The appearance of the artifacts on the reconstructed images was different from that on the source images. Such artifacts have the potential to simulate pathologic abnormalities.

Effect of spectacular reflection on out-of-plane ultrasonographic images reconstructed from three-dimensional data sets.

The effect of specular reflection on ultrasonographic images reconstructed out of plane to the plane of acquisition of a three-dimensional volumetric data set was studied using two in vitro phantoms that incorporated structures exhibiting specular reflection. The phantoms were scanned transversely (axially) to form three-dimensional data sets, with coronal cross-sectional images reconstructed perpendicular to the plane of acquisition of the data sets. Directly scanned, nonreconstructed coronal images of the phantoms also were obtained in the same planes and from the same areas as the reconstructed coronal images. The direct and reconstructed coronal images were compared. Owing to the inherent directionality of specular reflectors, the reconstructed coronal images differed from the directly scanned images in two ways, containing some hyperechoic regions that were not present at direct coronal scanning and failing to contain other hyperechoic areas that were present at direct coronal imaging. We conclude that sonographic images reformatted from volumetric data sets may have a different appearance than images scanned directly in the same plane, independent of other factors such as resolution. This should be taken into account when such reformatted images are interpreted.

The effect of contrast material on transcranial Doppler evaluation of normal middle cerebral artery peak systolic velocity.

BACKGROUND AND PURPOSE: Several recent studies have shown that sonographic contrast agents may affect transcranial Doppler evaluation of the arterial peak systolic velocity (PSV). Some investigators reported an increase in PSV, and others reported no change in PSV compared with baseline values. This study was conducted to determine the effect of sonographic contrast agent on PSV measured in normal middle cerebral arteries. METHODS: Continuous spectral Doppler sonography was performed on the right middle cerebral artery of 20 participants with angiographically proven normal intracranial vasculature. Videotaping was performed in each case from the initiation of the administration of contrast medium until the effect of the contrast agent on the PSV subsided. The PSV values were normalized for each participant, were pooled, and were plotted as a function of time. RESULTS: PSV increased in all participants after the administration of contrast material; the mean maximum increase was 24+/-7.4% (mean +/- standard deviation) (range, 15-36%). The mean duration of PSV increase was 320+/-97 s (range, 165-465 s). CONCLUSION: The middle cerebral artery PSV increased substantially after the administration of contrast material. This effect needs to be considered if velocity thresholds developed for disease detection without the use of contrast materials are used when contrast agents are administered.

Effect of downstream cross-sectional area of an arterial bed on the resistive index and the early systolic acceleration.

PURPOSE: To evaluate the effect of the increase in total cross-sectional area of arteries as they branch beyond the main trunks on the resistive index (RI) and early systolic acceleration (ESA). MATERIALS AND METHODS: An essentially noncompliant in vitro model that used a pulsatile pump, blood-mimicking fluid, and a branching tubing network that could be configured to produce a downstream cross-sectional area one, two, four, or eight times that of the feeding vessel was used to investigate the relationship, if any, between arterial bed cross-sectional area and the RI and ESA. RESULTS: The mean ESA in the branching network was inversely proportional to cross-sectional area, decreasing by approximately a factor of two for every doubling of the cross-sectional area. The mean RI in the branching network decreased with increasing cross-sectional area, but not as greatly as the ESA did; the mean RI in the bed with eight times the upstream cross-sectional area had an RI that was approximately three-fourths the upstream RI. These relationships are real, as the slopes of the plots (ESA vs cross-sectional area, P = .001; RI vs cross-sectional area, P < .02) are significantly different from zero. CONCLUSION: RI and ESA decrease as a result of increasing downstream cross-sectional diameter of the arterial bed.

Stenosis of the main artery supplying an organ: effect of end-organ vascular compliance on the poststenotic peak systolic velocity.

Prior studies have shown variable results using poststenotic peak systolic velocity to detect hemodynamically significant renal artery stenoses. We postulated that vascular compliance, which affects the arterial waveform and varies by a factor of at least 5 in vivo, affects the peak systolic velocity, perhaps explaining the aforementioned variable results using peak systolic velocity to detect stenoses. A hydraulic model was used to investigate the relationship between end-organ vascular compliance and the peak systolic velocity. The peak systolic velocity was found to be mildly dependent on vascular compliance, decreasing with decreasing compliance. These results help explain some of the reported variability using peak systolic velocity to detect hemodynamically significant renal artery stenoses, but the effect is not great enough to explain the variability completely. Other factors not investigated in this study must exist that also affect peak systolic velocity.

Frequency analysis of echo texture in tendon.

A texture discriminant based on spatial frequencies is proposed for characterizing B-scans of Achilles' tendon. The anisotropic echo texture of normal tendon has an ellipsoidal spatial spectrum that can be quantified by the ratio of the major-to-minor axis and by the direction of the major axis. Applying a moving window to the B-scan, a corresponding tissue elliptical axis ratio (TEAR) image is derived that segments out tendon. The algorithm was applied to B-scan images taken from 13 volunteers, 6 of whom had tendon abnormalities: tendon rupture (n = 3) or cholesterol deposits (xanthomas) in patients with heterozygous familial hypercholesterolemia (n = 3). The average TEAR value was 1.75 +/- 0.17 for normal tendon, 1.04 +/- 0.06 for torn tendon, and 1.31 +/- 0.16 for tendons with xanthomas. The dispersion of the directionality vectors was used to further differentiate tendons with xanthomas from normal tendons. This technique appears to be useful for characterizing both diffuse and focal tendon abnormalities.

Transabdominal power Doppler sonography of the normal early placenta.

OBJECTIVE: To evaluate how well transabdominal power Doppler sonography, a new method of colour Doppler sonography, visualizes the vasculature of the early placenta. METHODS: Evaluation of intrachorionic/intraplacental vasculature in 15 normal, singleton gestations of 8 to 18 weeks. RESULTS: Intrachorionic/intraplacental vessels were identified in all gestations, except the earliest (8 weeks). The number of vessels detected increased with increasing gestational age. Intrachorionic/intraplacental Doppler waveforms of maternal arterial origin were identified in gestations of 8.5, 9.5, and 11.5 weeks. CONCLUSIONS: Transabdominal power Doppler sonography detects intrachorionic/intraplacental vasculature at least as early as 8.5 weeks. Intervillous arterial flow of maternal origin is present in the first trimester, confirming the results of a recent transvaginal colour Doppler sonographic study, and contradicting earlier studies suggesting that such flow is not present in the first trimester.

Testicular plasmacytoma: appearance on gray-scale and power Doppler sonography.

A case of testicular plasmacytoma, a very rare neoplasm, is presented. The gray-scale and power Doppler sonographic findings are illustrated. The lesion appeared as a hypoechoic, intratesticular mass that was markedly hypervascular. When marked hypervascularity is present in a testicular mass in a patient unlikely to have orchitis on clinical grounds, plasmacytoma should be considered in the differential diagnosis.

Stenosis of the main artery supplying an organ: effect of end-organ vascular resistance on the poststenotic peak systolic velocity in an in vitro hydraulic model at Doppler US.

PURPOSE: To test the hypothesis that increased end-organ vascular resistance reduces blood flow to the kidney, thus reducing the mean velocity in the renal artery and secondarily lowering the peak systolic velocity (PSV). MATERIALS AND METHODS: An in vitro hydraulic model with a pulsatile pump, blood-mimicking fluid, interchangeable stenoses, and variable compliance and resistance was used to investigate the relationship between end-organ vascular resistance and poststenotic PSV. RESULTS: Poststenotic PSV was mildly dependent on end-organ vascular resistance and decreased with increasing resistance. CONCLUSION: The results help explain some of the reported variability from using poststenotic PSV to detect hemodynamically significant renal arterial stenoses, but the effect is not great enough to completely explain the variability. Other factors not investigated in this study must be at work as well.

Relationship between the resistive index and vascular compliance and resistance.

PURPOSE: To evaluate the dependence of the resistive index (RI) on not only vascular resistance but also vascular compliance. MATERIALS AND METHODS: An in vitro model that made use of a pulsatile pump, blood-mimicking fluid, and variable compliance and resistance was used to investigate the relationship between the RI and both vascular compliance and resistance. RESULTS: In the absence of vascular compliance, the RI was independent of vascular resistance. With vascular compliance, the RI was dependent on vascular resistance and increased with increasing resistance. The higher the compliance, the more the RI was affected by resistance. CONCLUSION: The RI is misnamed and should actually be called the "impedance index" because resistance and compliance interact to alter the Doppler arterial waveform. A greater understanding of this relationship may enable future studies that take both resistance and compliance into account to better detect pathologic conditions.

Utility of a linear array ultrasound endoscope in the evaluation of suspected pancreatic disease.

Endoscopic ultrasonography (EUS) is currently being used to evaluate and stage pancreaticobiliary malignancies and neuroendocrine tumors, and to perform aspiration for cytologic diagnosis. There are currently two different commercially available EUS systems for clinical use. One system uses a mechanical radial sector scanner oriented in a plane perpendicular to the long axis of the endoscope, and the other uses an electronic convex scanner that is oriented in the long axis of the endoscope. The vast majority of the current literature reports experience using the radial scanning device in the evaluation of pancreaticobiliary abnormalities. We prospectively evaluated the linear probe as the sole instrument for EUS in 26 patients with suspected pancreatic disease. The results of the endoscopic ultrasound examination were compared with the results of surgery or long-term clinical follow-up. The sensitivity and specificity of linear array EUS for benign pancreatic disease were 93.8% and 88.2%, respectively. The sensitivity and specificity for malignant disease of the pancreas were 80.0% and 88.9%, respectively. The linear array echoendoscope, employed as the only instrument for evaluation of the pancreas, is accurate in the evaluation of pancreatic disease. The addition of EUS-guided pancreatic biopsy would be anticipated to improve the sensitivity of the linear array instrument for detecting malignancy.

CT attenuation of fluid in breast cysts.

RATIONALE AND OBJECTIVES: The authors' purpose was to determine whether computed tomographic (CT) attenuation values of fluid in breast cysts could be in the range of values for soft tissue and could be correlated with protein content of the fluid. MATERIALS AND METHODS: Aspirate samples from 10 simple breast cysts were analyzed for protein content, and CT attenuation values were calculated by means of a breast phantom. A corrected attenuation value for breast-cyst fluid was calculated by using sterile water as a control. RESULTS: The mean corrected attenuation value for the cyst aspirate was 28.1 HU; most simple cysts have an attenuation value of only 10 HU. Protein concentration ranged from 0.9 to 2.4 g/dL. A significant, almost linear relationship was noted between protein content and attenuation value of cyst fluid (r = .85, P < .01). CONCLUSION: The CT attenuation values of breast cysts can be in the range of those of soft tissue. This high attenuation value is correlated with the high protein content of breast-cyst fluid. Therefore, an apparent circumscribed soft-tissue mass seen within the breast at CT may represent a simple cyst.

Sonographic detection of xanthomas in normal-sized Achilles' tendons of individuals with heterozygous familial hypercholesterolemia.

OBJECTIVE: The objective of this study was to evaluate how well high-frequency linear array sonography reveals xanthomas in the Achilles' tendons of individuals with heterozygous familial hypercholesterolemia before the xanthomas enlarge the tendons enough to become palpable. SUBJECTS AND METHODS: Both Achilles' tendons of 23 individuals (18 female and five male; age range, 16-69 years old) who had heterozygous familial hypercholesterolemia but no clinically apparent Achilles' tendon xanthomas were studied with high-frequency linear array sonography. Hypoechoic areas, consistent with xanthomas, were noted. RESULTS: Xanthomas were revealed in 36 (78%) of 46 tendons and 19 (83%) of 23 individuals. CONCLUSION: Sonography reveals Achilles' tendon xanthomas in many individuals with heterozygous familial hypercholesterolemia before the xanthomas are clinically apparent. Because tendon xanthomas in a hypercholesterolemic individual are essentially pathognomonic of heterozygous familial hypercholesterolemia and are a mainstay in its diagnosis, our study suggests that sonography is useful in the early diagnosis of heterozygous familial hypercholesterolemia.

Normalizing fractional moving blood volume estimates with power Doppler US: defining a stable intravascular point with the cumulative power distribution function.

PURPOSE: To normalize the power Doppler ultrasound (US) signal to the expected signal from 100% blood in the calculation of a fractional moving blood volume estimate. MATERIALS AND METHODS: To locate the signal from flowing blood with a consistent backscatter coefficient, the authors estimated the knee of the cumulative Doppler power distribution function. They used a flow-tube phantom to test the use of this knee to locate a radial position that would fall into a region of high shear stress and minimal rouleaux formation. They also studied how well the method normalized fractional moving blood volume estimates of the right renal cortex in a volunteer when simulating different body habitus and in a group of six healthy volunteers to estimate variability. RESULTS: Over five flow velocities and over undersaturated to severely oversaturated receiver gains, the calculated flow-tube area was a mean 89% +/- 7 (+/- standard deviation) of a standard. In humans, the technique normalized the fractional moving blood volume estimates over an 8-dB receiver gain variation; the mean +/- standard deviation of fractional moving blood volume estimates for the six volunteers was 37.6% +/- 3.6. CONCLUSION: Vascularity estimates with power Doppler US are feasible with a normalization scheme based on the cumulative Doppler power distribution function.

Use of intravenous contrast material in transcranial sonography.

RATIONALE AND OBJECTIVES: The appearance of the intracranial vasculature was compared on power and color Doppler ultrasound (US) scans obtained with and without a microbubble contrast agent. MATERIALS AND METHODS: Nine patients (three men, six women) aged 42-70 years (mean age, 53 years) participated in the study. Seven patients underwent both color Doppler US and power Doppler US before and after intravenous administration of contrast agent, and two underwent only color Doppler US. All patients had previously undergone cerebral angiography. RESULTS: Before contrast material was administered, power Doppler US was more sensitive than color Doppler US in the detection of intracranial vessels (P < .05); neither technique depicted the entire circle of Willis in eight of nine patients. Postcontrast power Doppler US depicted more vascular segments than postcontrast color Doppler US (P < .01) or precontrast power Doppler US (P < .01). Use of intravenous contrast material enabled the entire circle of Willis to be evaluated from a single temporal bone acoustic window with both power Doppler US and color Doppler US in all patients. Contrast-enhanced power Doppler US depicted vessels not shown by enhanced color Doppler US. CONCLUSION: Contrast-enhanced power Doppler US depicted more vessels, better demonstrated specific vascular segments, and provided better vascular definition of the intracranial vasculature than contrast-enhanced color Doppler US or unenhanced power Doppler US.

Use of Doppler sonography for revealing hepatic artery stenosis in liver transplant recipients.

OBJECTIVE: The goal of our study was to evaluate the use of duplex Doppler sonography for revealing hepatic artery stenosis (HAS) in patients who have undergone liver transplantation. MATERIALS AND METHODS: Forty-six patients with spectral Doppler waveforms obtained from the hepatic artery and with subsequent arteriography were reviewed retrospectively. Arterial waveforms, resistive indexes (RIs), and systolic acceleration times (SATs) were evaluated by one reviewer who was unaware of the arteriographic findings. The mean interval between the two examinations was 2.8 days. Arteriograms that revealed a stenosis of greater than 50% were classified as abnormal. RESULTS: Of the 46 patients, 21 (46%) had a significant stenosis. Patients who had HAS had significantly (p < .05) prolonged SATs (0.08 +/- 0.03 sec versus 0.06 +/- 0.02 sec) and reduced RIs (0.49 +/- 0.05 versus 0.66 +/- 0.05) compared with patients who did not have HAS. Optimal thresholds for HAS detection were RIs less than 0.55 and SATs greater than 0.08 sec. HAS was found in 14 of 15 patients who had both abnormal RIs and SATs. Of the remaining 31 patients, 12 had abnormal values for RI or SAT. Of these 12 patients, three had HAS. Thus, 19 patients had normal RIs and SATs; however, four of these patients were found to have an arterial stenosis. In our 46 patients, abnormal values for both RI and SAT were 67% sensitive and 96% specific for stenosis. When at least one abnormal value was found on Doppler imaging, sensitivity and specificity for stenosis were 81% and 60%, respectively. CONCLUSION: Duplex Doppler imaging can noninvasively reveal HAS. Abnormal values for both RI and SAT proved to be a more accurate predictor of stenosis than either RI or SAT as independent parameters.

Renal transplant evaluation with power Doppler sonography.

This study was performed to determine if the marked variation we had previously noted in the power Doppler sonographic appearance of renal transplants correlated with disease, 22 renal transplants were scanned with power Doppler at 5 MHz, with biopsies being taken within 1 h in 17 kidneys and within 48 h in four other kidneys. Biopsy was not performed in one kidney with distal ureteral obstruction. Biopsy results were complex with many coexistent abnormalities; classification was based upon the predominant abnormality. Cortical vascularity was subjectively evaluated as normal, decreased or markedly decreased, and graded as 0, 1 or 2, respectively, and was compared with biopsy results, serum creatinine levels and resistive index. Cortical vascularity gradings were: 0 (12 cases); 1 (7 cases); and 2 (3 cases). The large number of disease categories (cellular rejection, 11 cases; vascular rejection, 5 cases; IgA nephropathy, 1 case; cyclosporin toxicity, 3 cases; obstruction, 1 case; and lupus nephropathy, 1 case) in relation to the number of vascular grades and number of kidneys precluded statistical analysis of cortical vascularity for rejection. However, vascularity did not appear to correlate with rejection, the three severest cases of vascular rejection having normal (grade 0) vascularity. There was no statistically significant correlation of vascular grade with creatinine levels or resistive index. In conclusion, subjective analysis of the power Doppler sonographic appearance of renal transplants does not appear to aid in their evaluation.

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.