The Usefulness of Pulsatile Flow Detection in Measuring Resistive Index in Renal Doppler US

Objective

To assess the usefulness of pulsatile flow detection (PFD), a newly developed function of color Doppler US, in measuring resistive index (RI) in renal Doppler US and to compare it with conventional color Doppler (CCD).

Materials and Methods

Fifty-six kidneys in 31 patients were randomly selected and divided into two groups. In group A, RI was measured first with the aid of CCD, and then with PFD. In group B, data were obtained in the reverse order. The time required for each RI measurement was recorded in seconds. The quality of the Doppler spectral waveform was subjectively graded as 0, 1, or 2 and examination time and waveform quality were compared between PFD and CCD.

Results

The time required to measure RI with PFD (PFD time) was less than with CCD (CCD time) (mean 42.7 secs vs. mean 70.3 secs; p = 0.031). There was no significant difference in PFD time between group A and B, but CCD time was shorter in group B (70.3 secs vs. 24.6 secs; p = 0.0004). Spectral waveform quality was not significantly different between PFD and CCD.

Conclusion

The time required to measure RI in kidneys can be shortened with the aid of the PFD function in color Doppler US without affecting the quality of the examination.     

Hepatic Hemangiomas: Spectrum of US Appearances on Gray-scale, Power Doppler, and Contrast-Enhanced US

Because US plays a key role in the initial evaluation of hepatic hemangiomas, knowledge of the entire spectrum of US appearances of these tumors is important. Most hemangiomas have a distinctive US appearance, and even with those with atypical appearances on conventional gray-scale US, specific diagnoses can be made using pulse-inversion harmonic US with contrast agents. In this essay, we review the spectrum of US appearances of hepatic hemangiomas on conventional gray-scale, power Doppler, and pulse-inversion harmonic US with contrast agents.     

Focal Hepatic Lesions: Evaluation with Contrast-Enhanced Gray-Scale Harmonic US

Objective

To determine the findings of various focal hepatic lesions at contrast-enhanced gray-scale ultrasound (US) using a coded harmonic angio (CHA) technique and emphasizing lesion characterization.

Materials and Methods

The study involved 95 patients with 105 focal hepatic lesions, namely 51 hepatocellular carcinomas (HCCs), 22 metastases, 22 hemangiomas, four cases of focal nodular hyperplasia (FNH), and six nontumorous nodules. After the injection of a microbubble contrast agent (SH U 508A), gray-scale harmonic US studies using a CHA technique were performed with a combination of continuous scanning to assess the intratumoral vasculature (vascular imaging) and interval-delay scanning to determine the sequential enhancement pattern (acoustic emission imaging). Each imaging pattern was categorized and analyzed.

Results

At vascular imaging, 69% of HCCs (35/51) showed irregular branching vessels, while in 91% of metastases (20/22) a peripherally stippled pattern was observed. Intratumoral vessels were absent in 95% of hemangiomas (21/22) and all nontumorous lesions (6/6), while in 75% of FNHs (3/4) a spoke-wheel pattern was evident. At acoustic emission imaging, 71% of HCCs (36/51) showed heterogeneous enhancement and 86% (19/22) of metastases showed rim- or flame-like peripheral enhancement during the early phase, with washout occurring in all HCCs and metastases (100%, 73/73) during the late phase. In hemangiomas, enhancement was either peripheral and nodular (19/22, 86%) or persistent and homogeneous (3/22, 14%), and 75% of FNHs (3/4) became isoechoic during the late phase.

Conclusion

At contrast-enhanced gray-scale US using a CHA technique, a period of continuous scanning depicted the intratumoral vasculature, and interval-delay scanning demonstrated the sequential enhancement pattern. The characteristic findings of various focal hepatic lesions were thus determined.     

Use of a decision-analytic model to support the use of a new oral US contrast agent in patients with abdominal pain

RATIONALE AND OBJECTIVES: The authors performed this study to compare the cost and diagnostic abilities of ultrasound (US) performed with and without the use of an oral contrast material recently approved by the U.S. Food and Drug Administration. MATERIALS AND METHODS: An interactive decision-analytic model was constructed to compare US performed with and without contrast material (SonoRx; Bracco Diagnostics) for the evaluation of patients with abdominal pain who were suspected of having pancreatic disease. The model considered all resources that might be used to evaluate a patient suspected of having pancreatic disease (eg, US, computed tomography [CT], endoscopic retrograde cholangiopancreatography, fine-needle aspiration biopsy, and open biopsy). The literature and an expert panel were the clinical data sources. Cost estimates were based on Medicare and non-Medicare reimbursements. The primary cost-effectiveness measure was the cost to achieve a diagnosis. RESULTS: SonoRx-enhanced US was less expensive than unenhanced US ($714 vs $808, respectively, with Medicare costs; $1,612 vs $1,878, respectively, with non-Medicare costs) and as effective (0.785 vs 0.782, respectively). SonoRx-enhanced US was more cost-effective than unenhanced US ($909 vs $1,034, respectively, with Medicare costs; $2,052 vs $2,401, respectively, with non-Medicare costs). This relationship was maintained throughout extensive sensitivity analyses. CONCLUSION: SonoRx-enhanced US is more cost-effective than unenhanced US, primarily because it avoids the need for CT. CT may be avoided owing to the higher probability of obtaining optimal US scans with oral contrast material.     

Assessment of hyperemia in acute appendicitis: Comparison between power Doppler and color Doppler sonography

The purpose of our study was to compare power Doppler sonography (US) and conventional color Doppler US in the diagnosis of acute appendicitis by revealing local signs of hyperemia. One hundred consecutive patients (46 males and 54 females, ages 7–61 years; mean, 24.7 years) with clinically suspected acute appendicitis were prospectively examined with power Doppler US and conventional color Doppler US. Of 38 patients who subsequently underwent surgery, appendicitis was proven in 34. The remaining 62 patients who were not submitted to surgery had no clinical evidence of appendicitis over a 2- to 6-month follow-up. At gray-scale US, the appendix was visualized in 30 (88.2%) of the 34 cases with pathologically proven acute appendicitis. Power Doppler US depicted a moderate to marked hypervascularity of the appendiceal wall and surrounding mesoappendix in 28 (93.3%) of these 30 patients. At conventional color Doppler US, flow signal within the appendiceal wall and surrounding mesoappendix was shown in only 21 (70%) of 30 cases (P<0.05). No false-positive diagnosis was made at either power or color Doppler US among the 62 patients without appendicitis. Power Doppler US is more sensitive than conventional color Doppler imaging for revealing signs of local hyperemia in acute appendicitis.     

Colour Doppler flow imaging ultrasonography versus venography as screening method for asymptomatic postoperative deep venous thrombosis

Objective: To evaluate colour Doppler flow imaging ultrasonography (CDFI), compared with venography, as a screening method for postoperative deep venous thrombosis (DVT) in a clinical trial on thromboprophylaxis. Methods: Patients undergoing major abdominal or thoracic surgery were prospectively screened for DVT by CDFI. Patients were examined preoperatively, and on postoperative days 1, 3, 7, 14, 21, and 28. When the CDFI was positive venography was performed. Bilateral venography was performed on day 28 in all patients. The study group comprised 82 patients who underwent CDFI and venography on the same day: four because of suspected DVT (positive CDFI), and 78 on day 28 according to protocol. Results: DVT was detected by venography in seven patients, in three of whom CDFI was positive. CDFI was falsely positive in one case. There were two popliteal and five calf DVTs, of which CDFI detected one and two, respectively. The sensitivity of CDFI was 43%, the specificity 99%. The PVpos for CDFI was 75%, and the PVneg 96%. Conclusion: Due to low sensitivity, CDFI cannot stand alone as a screening method for asymptomatic postoperative DVT.     

Pulsed and color Doppler sonographic findings of penile Mondor's disease.

This report describes the color and pulsed Doppler US findings of penile Mondor's disease. The pulsed Doppler US findings of penile Mondor's disease have not been previously published, so we report here for the first time on the cavernosal arterial flow signal pattern of penile Mondor's disease. Penile Mondor's disease is rare disease that's characterized by thrombosis in the dorsal vein of the penis. The previous reports on penile Mondor's disease are concerned with the color Doppler US finding without the flow signals in this area, but these findings are insufficient to understand the hemodynamics in penile Mondor's disease. We report for the first time on a cavernosal artery flow signal pattern of low peak systolic velocity and high-resistance.     

Evaluation of deep vein thrombosis with multidetector row CT after orthopedic arthroplasty: a prospective study for comparison with Doppler sonography

OBJECTIVE: This prospective study evaluated the ability of indirect 16-row multidetector CT venography, in comparison with Doppler sonography, to detect deep vein thrombosis after total hip or knee replacement. MATERIALS AND METHODS: Sixty-two patients had undergone orthopedic replacement surgery on a total of 30 hip joints and 54 knee joints. The CT venography (scan delay time: 180 seconds; slice thickness/increment: 2/1.5 mm) and Doppler sonography were performed 8 to 40 days after surgery. We measured the z-axis length of the beam hardening artifact that degraded the image quality so that the presence of deep vein thrombosis couldn't be evaluated on the axial CT images. The incidence and location of deep vein thrombosis was analyzed. The diagnostic performance of the CT venograms was evaluated and compared with that of Doppler sonography as a standard of reference. RESULTS: The z-axis length (mean +/- standard deviation) of the beam hardening artifact was 4.5 +/- 0.8 cm in the arthroplastic knees and 3.9 +/- 2.9 cm in the arthroplastic hips. Deep vein thrombosis (DVT) was found in the popliteal or calf veins on Doppler sonography in 30 (48%) of the 62 patients. The CT venography has a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 90%, 97%, 96%, 91% and 94%, respectively. CONCLUSION: The ability of CT venography to detect DVT was comparable to that of Doppler sonography despite of beam hardening artifact. Therefore, CT venography is feasible to use as an alternative modality for evaluating post-arthroplasty patients.     

Sonographic Evaluation of Breast Nodules: Comparison of Conventional, Real-Time Compound, and Pulse-Inversion Harmonic Images

Objective

To compare the use of conventional, real-time compound, and pulse-inversion harmonic imaging in the evaluation of breast nodules.

Materials and Methods

Fifty-two breast nodules were included in this study, conducted between May and December 2000, in which conventional, real-time compound, and pulse-inversion harmonic images were obtained in the same plane. Three radiologists, each blinded to the interpretations of the other two, evaluated the findings, characterizing the lesions and ranking the three techniques from grade 1, the worst, to grade 3, the best. Lesion conspicuity was assessed, and lesions were also characterized in terms of their margin, clarity of internal echotexture, and clarity of posterior echo pattern. The three techniques were compared using Friedman''s test, and interobserver agreement in image interpretation was assessed by means of the intraclass correlation coefficient.

Results

With regard to lesion conspicuity, margin, and internal echotexture of the nodules, real-time compound imaging was the best technique (p < 0.05); in terms of posterior echo pattern, the best was pulse-inversion harmonic imaging (p < 0.05). Real-time compound and pulse inversion harmonic imaging were better than conventional sonography in all evaluative aspects. Interobserver agreement was greater than moderate.

Conclusion

Real-time compound and pulse-inversion harmonic imaging procedures are superior to conventional sonography in terms of both lesion conspicuity and the further characterization of breast nodules. Real-time compound imaging is the best technique for evaluation of the margin and internal echotexture of nodules, while pulse-inversion harmonic imaging is very effective for the evaluation of the posterior echo patterns.     

Correlation of power Doppler with microvessel density in assessing prostate needle biopsy

AIM: To correlate hypervascular power Doppler ultrasonography with the histological evaluation of microvasculature in the prostate using trans-rectal ultrasound (TRUS)-guided needle biopsy. MATERIALS AND METHODS: Ninety-six patients with a lower urinary tract symptoms (LUTS) and prostate specific antigen (PSA) value more than 4 ng/ml were evaluated using power Doppler ultrasonography before biopsy. The vascularity of the peripheral zone was graded on a scale of PZ0 to PZ2. Core needle biopsies were immunostained with CD31(DAKO) and counting was performed manually on separate high power fields (HPF; x 400) in areas containing the highest number of vessels. RESULTS: There was a significant correlation between the grading system used for power Doppler and the microvessel density (MVD; PZ0 28.61 +/- 8.97,PZ1 36.00 +/- 12.11 & PZ2 64.008 +/- 15.86; p < 0.001). There was also a significant difference in MVD between benign, malignant and tissue cores with atypia and prostatic intra-epithelial neoplasia (PIN; p < 0.001 and p < 0.018 respectively). There was a significant correlation between malignant tissue having a higher Gleason score and increased MVD (p < 0.001) Furthermore, cancer biopsies having a high flow PZ2 are nearly twice as likely (63.2%) to have a Gleason score of 7 or more when compared those having a Gleason score of less than 7 (36.8%). CONCLUSION: The grading system of assessing the power Doppler flow signals appears to be of value as an indicator of MVD. It also correlates with a higher Gleason score and this may reflect the clinical outcome in prostate cancer. It deserves further study and evaluation as a prognostic indicator.     

Contrast-enhanced power Doppler US in the diagnosis of renal pseudotumors

The term "pseudotumor" is used to refer to several anatomic variants that can simulate a renal mass, the most frequent of which are hypertrophied column of Bertin, persistence of fetal lobation, and the dromedary or splenic hump. We describe the findings of power Doppler US after the ultrasound contrast agent (Levovist, Schering, Berlin, Germany) administration in 4 patients with a renal focal lesion in whom gray-scale and baseline power Doppler US was not able to certainly differentiate pseudotumor from neoplasm.     

Use of sonicated albumin (infoson) to enhance arterial spectral and color Doppler imaging

Purpose To examine the effect of an ultrasound contrast medium (UCM), Infoson, on Doppler examination of stenotic arteries. Methods Stenoses were created in the common carotid artery of six piglets, and examined with spectral Doppler and color Doppler imaging during UCM infusion in the left ventricle. Results UCM caused a mean increase in recorded maximal systolic and end-diastolic velocities of 5% and 6%, respectively, while blood flow remained constant. Increased spectral intensity with UCM was accompanied by spectral broadening. Reduction of spectral intensity by adjustment of Doppler gain counteracted the velocity effects and the spectral broadening. With color Doppler, UCM caused dose-dependent color artifacts outside the artery. Flow in narrow stenoses could be visualized with UCM. Conclusion The effects of UCM on velocity measurements were slight, and were related to changes in spectral intensity. With color Doppler, UCM may facilitate flow detection, but color artifacts may interfere.     

Marked increase in flow velocities during deep expiration: A duplex doppler sign of celiac artery compression syndrome

Symptoms of chronic mesenteric ischemia develop when the celiac artery is constricted by the median arcuate ligament of the diaphragm. Lateral aortography is the primary modality for diagnosing ligamentous compression of the celiac artery. However, duplex Doppler sonography performed during deep expiration can cause a marked increase in flow velocities at the compressed region of the celiac artery and suggest the diagnosis of celiac arterial constriction due to the diaphragmatic ligament. RID=" ID=" <E5>Correspondence to:</E5> A. Erden, M.D., Hafta sokak. 23/6, Gaziosmanpa&scedil;a, 06700 Ankara, Turkey     

Detection of Hepatic VX2 Tumors in Rabbits: Comparison of Conventional US and Phase-Inversion Harmonic US During the Liver-Specific Late Phase of Contrast Enhancement

Objective

To compare phase-inversion sonography during the liver-specific phase of contrast enhancement using a microbubble contrast agent with conventional B-mode sonography for the detection of VX2 liver tumors.

Materials and Methods

Twenty-three rabbits, 18 of which had VX2 liver tumor implants, received a bolus injection of 0.6 g of Levovist (200 mg/ml). During the liver-specific phase of this agent, they were evaluated using both conventional sonography and contrast-enhanced phase-inversion harmonic imaging (CE-PIHI). Following sacrifice of the animals, pathologic analysis was performed and the reference standard thus obtained. The conspicuity, size and number of the tumors before and after contrast administration, as determined by a sonographer, were compared between the two modes and with the pathologic findings.

Results

CE-PIHI demonstrated marked hepatic parenchymal enhancement in all rabbits. For VX2 tumors detected at both conventional US and CE- PIHI, conspicuity was improved by contrast-enhanced PIHI. On examination of gross specimens, 52 VX2 tumors were identified. Conventional US correctly detected 18 of the 52 (34.6%), while PIHI detected 35 (67.3%) (p < 0.05). In particular, conventional US detected only three (8.3%) of the 36 tumors less than 10 mm in diameter, but CE-PIHI detected 19 such tumors (52.8%) (p < 0.05).

Conclusion

Compared to conventional sonography, PIHI performed during the liver-specific phase after intravenous injection of Levovist is markedly better at detecting VX2 liver tumors.     

Imaging Features of Gray-Scale and Contrast-Enhanced Color Doppler US for the Differentiation of Transient Renal Arterial Ischemia and Arterial Infarction

Objective

To characterize the imaging features on gray-scale and contrast-enhanced color Doppler US images which differentiate renal ischemia from renal infarction.

Materials and Methods

The segmental renal arteries of eight healthy rabbits were surgically ligated. In four of these rabbits, the ligated renal artery was released 60 minutes after arterial occlusion to cause transient ischemia. In the remaining four rabbits, the arterial ligation was retained to cause a permanent infarction. The gray-scale and contrast-enhanced color Doppler US imaging features of the involved renal parenchyma of both ischemia and infarction groups were compared with respect to the presence or absence of parenchymal swelling, echogenicity changes, tissue loss and perfusion defects.

Results

Parenchyma swelling, echogenic changes, tissue loss and perfusion defects were found to be more extensive in the infarction than the ischemia group. The hyperechoic areas reperfused with blood flow recovered normal echogenicity and perfusion, whereas the hyperechoic areas without reperfusion became renal infarcts.

Conclusion

Gray-scale and contrast-enhanced color Doppler US showed that the hyperechoic areas with reperfusion may reverse to normal parenchyma and allow the differentiation of renal ischemia from renal infarction.     

Colour Doppler signal enhancement of intrarenal vasculature of the rabbit with Perflubron

The colour Doppler signal enhancement of the intrarenal vasculature of the kidney was studied after intravenous infusion of Perflubron. This enhancement was evaluated qualitatively and semi-quantitatively. Nine rabbits received 1 g/kg of a 100% w/v Perflubron emulsion [perfluorooctylbromide (PFOB), Alliance Pharmaceutical] intravenously. Then, two groups of 2 rabbits received 2 and 3 g/kg respectively, and 1 rabbit received 4 g/kg. The kidneys were imaged longitudinally on a colour Doppler unit with a 7.5 MHz transducer. Signal enhancement was evaluated semi-quantitatively by counting the levels of signal threshold that had to be subtracted to reproduce the baseline image. This measurement was performed 1, 3, 5, 10, 30, 45, 60, 90 and 120 min after infusion. We found that detection of very small vessels deep into the parenchyma was possible with Perflubron. In the group that received 1 g/kg Perflubron significant variations in signal enhancement were noted. The curve of mean signal enhancement showed a maximum Doppler signal at about 15 min, which slightly and progressively decreased during the next hour. With the 2, 3 and 4 g/kg doses, enhancement was constant and proportional to the infused dose. Perflubron emulsion allows significant Doppler enhancement on colour flow imaging, providing better visualisation of deep parenchymal small vessels. A dose of 1 g/kg seems adequate for this purpose.Correspondence to: N. Grenier     

Differentiation of hepatocellular adenoma and focal nodular hyperplasia of the liver: comparison of power Doppler imaging and conventional color Doppler sonography

The aim of our study was to compare the diagnostic efficacy of power Doppler imaging and conventional color Doppler sonography for differentiating between hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) of the liver. Thirty-one focal liver lesions (in 29 patients) with histologic proof of HCA (n = 9) or FNH (n = 22) were studied with power and color Doppler sonography according to a standardized examination protocol. The size of the lesions ranged between 1.5 and 14.5 cm (HCA, 3.5–14.5 cm, mean ± SD 7.3 ± 3.3 cm; FNH, 1.5–9.1 cm, mean ± SD 5.1 ± 2.1 cm). Intratumoral vessels with a venous Doppler spectrum, associated with either pulsatile or continuous peripheral flow, were detected in HCA (eight of nine lesions by power Doppler imaging and six of nine by color Doppler imaging) but not in FNH. In contrast, color signals with an arterial Doppler spectrum, radiating from the center to the periphery of the lesion, were depicted in FNH (20 of 22 cases by power Doppler imaging and 15 of 22 by color Doppler sonography) but not in HCA. Differentiation of HCA and FNH was achieved in 28 of 31 cases (90 %) by power Doppler imaging and in 21 of 31 (68 %) by color Doppler sonography (p < 0.01). Power Doppler imaging is superior to conventional color Doppler sonography in the depiction of the intratumoral flow characteristics of HCA and FNH, and enables a more accurate differential diagnosis than color Doppler sonography. Received 13 January 1997; Revision received 24 February 1997; Accepted 28 March 1997