Radiologic Findings of Renal Inflammatory Pseudotumor: A Case Report

Renal inflammatory pseudotumor is a very rare benign condition of unknown etiology characterized by proliferative myofibroblasts, fibroblasts, histiocytes, and plasma cells. In the case we report, the lesion appeared on contrast-enhanced power Doppler US images as a well-defined hypoechoic mass with intratumoral vascularity, and on CT as a low-attenuated mass. Differentiation from malignant renal neoplasms was not possible.     

Echographic study with high-frequency and high-spatial resolution transducer in the evaluation of renal transplant in pediatric age

PURPOSE: We investigated the role of power Doppler US with a high-frequency and high-resolution transducer (13 MHz) in the visualization of interlobular arterioles in patients with normally functioning renal transplants or with chronic rejection. MATERIAL AND METHODS: We examined 15 patients (mean age 15 years; range 10-18 years) with a General Electric 500 MD unit using 7.5 and 13 MHz linear transducers. In all the patients serum creatinine and diuresis were evaluated; 4 patients underwent US-guided biopsy that resulted in the diagnosis of chronic rejection. RESULTS: Normally functioning renal transplants were found in 11 patients and chronic rejection was seen in 4. In normally functioning renal transplants, interlobular vessels could be depicted as "cortical blush" with the 7.5 MHz transducer; in the same patients power Doppler US with the 13 MHz transducer permitted a correct evaluation of interlobular vessels that were arranged in series like a palisade. In chronic rejection power Doppler US with the 13 MHz transducer better depicted cortical vascularity and showed irregular, narrow arteries. CONCLUSION: Power Doppler US with a 13 MHz transducer is particularly useful in children after renal transplants due to their reduced tissutal thickness. The lateral resolution of 13 MHz transducers (< 0.3 mm) allows to separate interlobular vessels from each other and the high frequency of the probe can depict interlobular vessels in the peripheral cortex. The optimal visualization of cortical vascularity with a 13 MHz transducer allows early detection of chronic rejection.     

From donor to recipient. Doppler US, power US and scintigraphy of kidney perfusion before and after transplantation

PURPOSE: To follow kidneys from the donor to the recipient by assessing whether perfusion changes occur by using duplex Doppler US, power Doppler US and scintigraphy. MATERIAL AND METHODS: The prospective study included 12 donors and their corresponding 12 recipients. For each donor, both donor kidneys were evaluated by duplex Doppler US, power Doppler US and scintigraphy 1 day before surgery. The same procedure was carried out on the renal allografts at days 1, 3, 5 and months 1 and 3 post-transplantation. Power Doppler findings were classified according to a grading system of 1 to 4. Resistive indices (RIs) were determined based on interlobar and segmental arterial flow. Peak systolic velocity and RIs of the main renal artery were also measured. A perfusion parameter named the peak-to-plateau ratio was calculated. Statistical analysis was performed using the paired-samples t-test. RESULTS: Intrarenal RI elevation and decreased renal artery peak systolic velocity was observed in normally functioning recipient kidneys. CONCLUSION: Duplex Doppler sonography demonstrated that transplanted kidneys had an increase in intrarenal vascular resistance at 1 month and a decrease in renal artery peak systolic velocity at 3 months post-transplantation. Scintigraphy and power Doppler US did not reveal any statistically significant perfusion change in normally functioning kidneys from donor to recipient.     

Vascularity of hepatocellular carcinoma: assessment with contrast-enhanced second-harmonic versus conventional power Doppler US

PURPOSE: To compare contrast material-enhanced harmonic power Doppler ultrasonography (US) with conventional power Doppler US in depicting the vascularity of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty patients with nodular HCCs (2.6-13.2 cm in diameter; mean diameter, 4.8 cm) were prospectively examined with both conventional and harmonic power Doppler US. US was performed with a 2-4-MHz curved linear-array transducer according to a standard examination protocol (1,000-Hz pulse repetition frequency, medium wall filter, and power gain of 55%-84% for conventional power Doppler US; 700-Hz pulse repetition frequency, low wall filter, and power gain of 95%-98% for harmonic power Doppler US). Serial, dynamic scans were obtained before intravenous injection of the contrast agent (SH U 508A) and at 30, 60, 90, 120, 180, 240, and 300 seconds after injection with both techniques. RESULTS: The number of intratumoral power Doppler US signals was similar with both techniques at 30-90 seconds after contrast agent injection; however, after 90 seconds, conventional power Doppler US depicted significantly more signals than did harmonic power Doppler US. Harmonic power Doppler US was superior to conventional power Doppler US in terms of power Doppler artifacts such as "blooming" or motion-related artifacts. CONCLUSION: Although the effective enhancement duration is relatively short compared with that for conventional power Doppler US, contrast-enhanced harmonic power Doppler US can be effective in evaluating the vascularity of HCCs because of the advantage of fewer power Doppler artifacts.     

Renal blood flow changes induced with endothelin-1 and fenoldopam mesylate at quantitative Doppler US: initial results in a canine study

PURPOSE: To evaluate quantitative Doppler ultrasonography (US) for assessing renal blood flow changes induced with endothelin-1 (ET-1) and fenoldopam mesylate in conscious dogs. MATERIALS AND METHODS: A blood flow probe was surgically implanted around the renal artery in eight adult dogs. Color and power Doppler US images were acquired in conscious restrained dogs during intravenous infusion of ET-1 and fenoldopam mesylate. Simultaneous with imaging, blood flow through the renal artery was measured with the implanted probe. The color level of the images within the region representing the kidney was analyzed to derive flow indices. These indices were compared with direct-flow measurements. RESULTS: The flow indices, color-weighted flow area (CWFA), and percentage of area of color, derived from color and power Doppler US images, correlated linearly with direct flow. The mean color level of color and power Doppler US images correlated weakly with direct flow. Pre- versus postinfusion CWFA decreased with all ET-1 infusions (P < or =.032). Infusion of fenoldopam mesylate increased CWFA in all cases (P < or =.032). CONCLUSION: Quantitative Doppler US enabled successful measurement of the flow changes induced with ET-1 and fenoldopam mesylate. Quantitative Doppler US is potentially useful as a noninvasive surrogate endpoint in evaluating the action of various therapeutic agents.     

Ultrasound of renal vessels

Kidneys are known as well-perfused organs and may undergo a variety amount of vascular pathological conditions such as renal artery stenosis, renal vein thrombosis, arteriovenous fistula, and aneurysms. Sonography is usually the first imaging method for renal vascular diseases. Modern US machines are now able to outline with great detail both main renal vessels and intraparenchymal vasculature of the kidney using color and power Doppler techniques. Knowledge about the use of different Doppler imaging modalities and typical sonographic findings of the most frequently conditions affecting renal vessels are of great importance. This article reviews the clinical applications of US and Doppler US techniques including basics and technological advances in the field of renal vascular diseases. Electronic Publication     

Doppler power with contrast media in the characterization of renal masses

PURPOSE: To report the results of a prospective study investigating the potentials of contrast-enhanced power Doppler in the diagnosis of expansive renal lesions. MATERIAL AND METHODS: From 1997 to October 30, 1999, we studied 59 expansive renal lesions (28 malignant, 31 benign) in 48 patients (mean age 55 years, range 10-79) with power Doppler US before and after the administration of an echo-enhancing agent (Levovist, Schering AG, Berlin, Germany). We identified 5 patterns of vascular architecture of the lesions, both before and after contrast agent administration, following the classification by Jinzaki e Coll. RESULTS AND DISCUSSION: Power Doppler US showed vascular structures in 34 patients. The administration of Levovist revealed vessels in 12/25 lesions which had none at baseline studies and in 6 cases vascularity was particularly evident. Color signals were enhanced in all the 34 vascularized lesions, which allowed better definition of vascular patterns. The characterization of vascular patterns with baseline power Doppler US helped improve diagnostic accuracy compared to gray-scale US (58% versus 32%) for hyperechoic lesions, complex cysts and pseudomasses. Independent of contrast agent administration, the integration of gray-scale and power Doppler modes increased diagnostic accuracy even further (76% correct diagnoses). CONCLUSIONS: In our series, the US contrast agent did not increase the diagnostic accuracy of power Doppler in the differential diagnosis of hyperechoic renal lesions; conversely, Levovist can be advantageous for the characterization of suspected pseudomasses and complex cysts.     

Cross-sectional imaging of idiopathic solitary renal vein varix: Report of two cases

Two cases of solitary renal vein varices are reported which presented as incidental findings on abdominal computed tomography (CT) and were initially thought to represent retroperitoneal lymph nodes. Contrast-enhanced CT, magnetic resonance imaging (MRI), and Doppler ultrasound (US), all demonstrated the vascular nature of these masses suggesting the correct diagnosis. When a rounded soft tissue density mass is seen on noncontrast-enhanced CT either in or contiguous to the renal hilum, a renal vein varix must be excluded. Doppler US, MRI, or dynamic contrast-enhanced CT should be done to exclude a renal varix as the cause.     

Renal parenchymal diseases: is characterization feasible with ultrasound?

Ultrasound (US) imaging of the kidneys has greatly improved in recent years with introduction of wideband transducers and advances is beamformer technology. US is often the first imaging technique to be employed in patients with renal failure, haematuria or proteinuria, after clinical and laboratory evaluation. After conventional US evaluation, Doppler US (DUS) and resistive indices (RIs) analysis provide renal functional evaluation. Anyway, both sensitivity and specificity of conventional US and DUS in renal parenchymal disease evaluation remains low. In the initial or mild clinical stages of renal parenchymal diseases, kidneys may present normal US morphological appearance and normal RIs values, whereas different renal parenchymal diseases may reveal similar appearance on US and DUS evaluation. Besides, different renal parenchymal diseases may present some distinct features on conventional US and DUS with colour Doppler (CD) and power Doppler (PD) evaluation, even though percutaneous renal biopsy is often necessary to reach definite diagnosis. Renal vasculitides and tubular-interstitial nephropathies are more frequently identified by conventional US and DUS than glomerular nephropathies, since glomerular component accounts only for 8% of the renal parenchyma, whereas the highest percentage is occupied by vascular and tubulo-interstitial component. Follow-up of acute renal failure, during and after medical treatment, is the most useful field of employment of conventional US and DUS techniques, since a progressive lowering of RIs is correlated to a progressive recovery of renal function.     

Current role of color Doppler ultrasound in acute renal failure]

Acute Renal Failure (ARF) is characterized by a rapid decline of the glomerular filtration rate, due to hypotension (prerenal ARF), obstruction of the urinary tract (post-renal ARF) or renal parenchymal disease (renal ARF). The differential diagnosis among different causes of ARF is based on anamnesis, clinical symptoms and laboratory data. Usually ultrasound (US) is the only imaging examination performed in these patients, because it is safe and readily available. In patients with ARF gray scale US is usually performed to rule out obstruction since it is highly sensitive to recognize hydronephrosis. Patients with renal ARF have no specific changes in renal morphology. The size of the kidneys is usually normal or increased, with smooth margins. Detection of small kidneys suggests underlying chronic renal pathology and worse prognosis. Echogenicity and parenchymal thickness are usually normal, but in some cases there are hyperechogenic kidneys, increased parenchymal thickness and increased cortico-medullary differentiation. Evaluation of renal vasculature with pulsed Doppler US is useful in the differential diagnosis between prerenal ARF and acute tubular necrosis (ATN), and in the diagnosis of renal obstruction. Latest generation US apparatus allow color Doppler and power Doppler evaluation of renal vasculature up to the interlobular vessels. A significant, but non specific, reduction in renal perfusion is usually appreciable in the patients with ARF. There are renal pathologic conditions presenting with ARF in which color Doppler US provides more specific morphologic and functional information. In particular, color Doppler US often provides direct or indirect signs which can lead to the right diagnosis in old patients with chronic renal insufficiency complicated with ARF, in patients with acute pyelonephritis, hepatic disease, vasculitis, thrombotic microangiopathies, and in patients with acute thrombosis of the renal artery and vein. Contrast enhanced US is another useful diagnostic tool in patients with ARF which has been recently introduced in clinical practice. Microbubble administration may reduce technical failure in the evaluation of the renal artery. Moreover, perfusion defects due to stenosis or thrombosis of the renal segmentary vessels are better recognized. New diagnostic possibilities of enhanced US include evaluation of both cortical and medullar vessels, and functional evaluation of renal perfusion. Measuring the transit time of the microbubbles is useful for the diagnosis of renal artery stenosis and, in transplanted kidneys, for differential diagnosis between ATN and acute rejection.     

The Use of Contrast-Enhanced Color Doppler Ultrasound in the Differentiation of Retinal Detachment from Vitreous Membrane

Objective

To compare the clinical utility of contrast-enhanced color Doppler US in the differentiation of retinal detachment (RD) from vitreous membrane (VM) with that of various conventional US modalities, and to analyze the enhancement patterns in cases showing an enhancement effect.

Materials and Methods

In 32 eyes examined over a recent two-year period, RD (n=14) and VM (n=18) were confirmed by surgery (n=28) or clinical follow-up (n=4). In all cases, gray-scale, color Doppler, and power Doppler US were performed prior to contrast injection, and after the intravenous injection of Levovist (Schering, Berlin) by hand for 30 seconds at a dose of 2.5 g and a concentration of 300 mg/mL via an antecubital vein, contrast-enhanced color Doppler US was performed. At Doppler US, the diagnostic criterion for RD and VM was whether or not color signals were visualized in membranous structures.

Results

Diagnostic accuracy was 78% at gray-scale US, 81% at color Doppler US, 59% at power Doppler US, and 97% at contrast-enhanced color Doppler US. The sensitivity of color Doppler US to color signals in RD increased from 57% to 93% after contrast enhancement.The enhancement patterns observed were signal accentuation (n=3), signal extension (n=2), signal addition (n=3), and new signal visualization (n=5).

Conclusion

Contrast-enhanced color Doppler US was the most accurate US modality for differentiating RD from VM, showing a significantly increased signal detection rate in RD.     

Comparison of harmonic and conventional power Doppler ultrasonography for assessment of slow flow in hyperechoic tissue: experimental study using a Doppler phantom

RATIONALE AND OBJECTIVES: Despite the advantages of depicting slow flow in small vessels, conventional power Doppler ultrasound (US) has a basic limitation, specifically that artifactual power Doppler signals mimic blood flow, especially in hyperechoic tissue. The purpose of this study was to compare harmonic power Doppler US with power Doppler US using a Doppler phantom under various parameter settings, focusing on the assessment of slow flow in the hyperechoic tissue. METHODS: While controlling the flow velocity (5 and 10 cm/s), pulse repetition frequency (500, 700, and 1,000 Hz), wall filter (low and medium), and Doppler gain (90%, 96%, and 100%), the authors performed both harmonic Doppler US and power Doppler US by using a Doppler phantom/flow control system. We measured and compared the relative intensities of the Doppler signals (0-250 scale) in both the vessels and hyperechoic tissue-mimicking materials with the two different imaging modalities. RESULTS: Power Doppler US with any combination of the four parameters evaluated depicted strong flow signals (mean, 213) that were superior to harmonic Doppler US (mean, 61). Relatively strong artifactual signals within the hyperechoic tissue-mimicking materials were noted on all power Doppler US studies (mean, 106) but nearly none on harmonic Doppler US (mean, 3). The contrast-to-noise ratio of harmonic Doppler US was significantly greater than that of power Doppler US. CONCLUSIONS: Harmonic Doppler US is more useful in assessing slow flow in hyperechoic tissue than power Doppler US because it produces fewer artifactual Doppler signals originating from stationary hyperechoic tissues, which can be misjudged as true signals on power Doppler US.     

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.     

Renal arteries in patients at risk of renal arterial stenosis: multicenter evaluation of the echo-enhancer SH U 508A at color and spectral Doppler US. Levovist Renal Artery Stenosis Study Group

PURPOSE: To assess SH U 508A in the diagnosis of suspected renal arterial stenosis by means of ultrasonography (US) and to confirm the safety of SH U 508A in a clinical setting. MATERIALS AND METHODS: A randomized crossover study was performed in 198 patients from 14 European centers who were referred for renal arterial angiography because they were suspected of having renal arterial stenosis. All patients underwent nonenhanced and SH U 508A-enhanced Doppler US of the renal arteries. Doppler criteria included measurement of renal arterial peak systolic velocity (threshold, 1.4-2.0 m/sec) in all centers and renoaortic ratio (threshold, 3.0-3.5) in nine. RESULTS: The number of examinations with successful results increased following enhanced Doppler US examination--160 (83.8%) compared with 122 (63.9%) with nonenhanced Doppler US (P = .001), including patients with obesity or renal dysfunction. Renal arterial stenosis (> or =50%) was detected at angiography in 72 patients. Results at enhanced Doppler US were in agreement with results at angiography more often than with results at nonenhanced Doppler US in the diagnosis or exclusion of renal arterial stenosis (P = .001). For patients examined with nonenhanced and enhanced Doppler US, sensitivity (80.0% and 83.7%, respectively) and specificity (80.8% and 83.6%, respectively) remained unchanged. There were no clinically important adverse events following use of SH U 508A. CONCLUSION: In patients suspected of having renal arterial stenosis, SH U 508A increased the number of diagnostic renal arterial Doppler studies.     

Role of echo-Doppler in the screening of renal artery stenosis in children with kidney transplants]

Renal artery stenosis (RAS) in renal transplanted pediatric patients is a long-term complication. The clinical suspicion must be considered when patients exhibit signs of impaired renal function or refractory hypertension, not associated with other complications of renal transplantation -i.e., acute or chronic rejection, glomerulonephritis, cyclosporine toxicity. The intermediate step between clinical suspicion and angiography is represented by Doppler US. The authors report their experience with Doppler US in the screening of RAS in a pediatric series of transplanted patients. The incidence of RAS in our series (54 transplanted kidneys, 46 of them included in the study) was 4.3%. A severe stenosis was demonstrated by both Doppler US and angiography in 2 patients, with 100% Doppler sensitivity. In both stenoses, Doppler US showed high systolic peaks (blood flow velocity > or = 2.5 m/s) and post-stenotic turbulence. Thanks to its high sensitivity, Doppler US is considered to be very useful in the screening of vascular complications in renal transplanted children.     

Nonpalpable breast lesions: evaluation with power Doppler US and a microbubble contrast agent-initial experience

PURPOSE: To evaluate power Doppler ultrasonography (US) performed with a microbubble US contrast agent in the differentiation of nonpalpable breast lesions. MATERIALS AND METHODS: Fifty nonpalpable breast lesions in 50 patients were prospectively evaluated with power Doppler US before and after injection of the contrast agent SH U 508A. Lesion vascularity and the morphology of vessels on US scans were analyzed and were correlated with histologic results. RESULTS: Surgical excision revealed 22 cancers and 28 benign lesions. At nonenhanced power Doppler US, eight (36%) of 22 cancers and four (14%) of 28 benign lesions were vascular. At contrast agent-enhanced power Doppler US, 21 (95%) cancers and six (21%) benign lesions were vascular (P <.001). Irregular vessels were seen in three cancers and one benign lesion at nonenhanced power Doppler US and in 11 cancers and one benign lesion at contrast-enhanced power Doppler US. By using the presence of vascularity in the mass as the diagnostic criterion for malignancy, the sensitivity, specificity, and positive and negative predictive values of power Doppler US changed from 36%, 86%, 67%, and 63%, respectively, to 95%, 79%, 78%, and 96% after contrast agent injection. CONCLUSION: Contrast-enhanced power Doppler US was superior to nonenhanced power Doppler US in the demonstration and characterization of tumor vascularity in nonpalpable breast lesions. Contrast-enhanced power Doppler US may be useful for the differentiation between nonpalpable breast cancers and benign tumors.     

Doppler US in rheumatic diseases with special emphasis on rheumatoid arthritis and spondyloarthritis

Developments in digital ultrasonography (US) technology and the use of high-frequency broadband transducers have increased the quality of US imaging, particularly of superficial tissues. Thus, US, particularly color US or power Doppler US, in which high-resolution transducers are used, has become an important imaging modality in the assessment of rheumatic diseases. Furthermore, therapeutic interventions and biopsies can be performed under US guidance during the assessment of lesions. In this era of effective treatments, such as biologics, improvements in synovial inflammation in rheumatoid arthritis as well as changes in enthesitis in spondyloarthropathies, including ankylosing spondylitis and psoriatic arthritis, can be monitored effectively using gray-scale and/or power Doppler US. US is also a good imaging modality for crystal arthropathies, including gout and pseudogout, in which synovitis, erosions, tophi, and crystal deposition within or around the joint can be visualized readily. Vascular and tenosynovial structures, as well as the salivary glands, can be assessed with US in vasculitis and connective tissue disorders, including systemic lupus erythematosus and Sjögren’s syndrome. Current research is focused on improving the sensitivity, specificity, validity, and reproducibility of US findings. In this review, we summarized the role of US, particularly power Doppler US, in rheumatic diseases and inflammation in superficial tissues.Developments in digital ultrasonography (US) technology and the use of high-frequency broadband transducers have increased the quality of US imaging, particularly of superficial tissues. The increase in spatial resolution has facilitated evaluation of normal and pathological structures using US, and the increased sensitivity of color Doppler US (CDUS) for low-flow signals has enabled the evaluation of vascularity in these structures.Thus, US, particularly CDUS or power Doppler US (PDUS), in which high-resolution transducers are used, has become the primary imaging modality for superficial tissues. US can be used as a first-step screening tool to assess the presence of superficial soft tissue masses and thus can be used to evaluate the need for other imaging techniques. High-frequency US, in some cases, allows more specific diagnoses by characterizing the anatomy of the superficial tissues and flow within the lesions or neighboring tissues (1–4).Indeed, US and Doppler US can define the cystic and solid nature of lesions and thus provide a final diagnosis, in some cases without the need for another imaging modality. Furthermore, therapeutic interventions and biopsies can be performed under US guidance during the assessment of lesions. Changes in the size and vascularity of lesions, clinical responses, and local tumor recurrence can also be followed by CDUS/PDUS (1, 3). In this review, we emphasized the role of US, particularly PDUS, in rheumatic diseases and inflammation in superficial tissues.     

Renal arterial stenosis: prospective comparison of color Doppler US and breath-hold, three-dimensional, dynamic, gadolinium-enhanced MR angiography

PURPOSE: To compare color Doppler ultrasonography (US) with fast, breath-hold, three-dimensional, gadolinium-enhanced magnetic resonance (MR) angiography in detecting renal arterial stenosis. MATERIALS AND METHODS: Forty-five patients with clinical suspicion of renovascular disease were prospectively examined with intra- and extrarenal color Doppler US and breath-hold, gadolinium-enhanced MR angiography. Digital subtraction arteriography (DSA) was the standard of reference in all patients for the number of renal arteries and degree of stenosis. RESULTS: DSA depicted 103 arteries and 52 stenoses. Color Doppler US was nondiagnostic in two examinations. Significantly more of 13 accessory renal arteries were detected with MR angiography (n = 12) than with color Doppler US (n = 3; P <.05). For assessing all stenoses, the sensitivity and accuracy were 94% and 91%, respectively, for MR angiography and 71% and 76%, respectively, for US (P <.05). The sensitivity was higher for MR angiography (100%) than for US (79%; P <.05) in diagnosing stenoses with at least 50% narrowing. The specificity, accuracy, and negative predictive value in diagnosing stenoses of at least 50% narrowing were 93%, 95%, and 100% for MR angiography and 93%, 89%, and 90% for US. CONCLUSION: Breath-hold, gadolinium-enhanced MR angiography is superior to color Doppler US in accessory renal artery detection. Although the specificity of MR angiography is similar to that of color Doppler US, MR angiography has a better sensitivity and negative predictive value in depicting renal arterial stenoses.     

Focal liver lesions in cirrhosis: value of contrast-enhanced ultrasonography compared with Doppler ultrasound and α-fetoprotein levels

Purpose

This study aimed to evaluate the diagnostic value of contrast-enhanced ultrasound (CEUS) in characterising focal liver lesions in cirrhosis and to validate its use in lesions discovered during surveillance for hepatocellular carcinoma (HCC).

Materials and methods

Between 2003 and 2006, 128 cirrhotic patients with focal liver lesions at baseline ultrasonography (US) were studied by power colour Doppler US (Doppler US) and CEUS. Serum alpha-fetoprotein (AFP) levels were assessed in all patients. Fine-needle biopsy or other reference modalities such as computed tomography (CT), magnetic resonance imaging (MRI) or digital subtraction angiography (DSA) were used as the gold standard. The accuracy of baseline US, Doppler US, AFP levels, combined US and AFP levels and combined US, Doppler US and CEUS in characterising focal liver lesions was assessed. Diagnostic performance was compared using the McNemar test.

Results

A total of 207 focal liver lesions (101 benign and 106 malignant) were identified in 128 patients. CEUS sensitivity and specificity for lesion characterisation were 96.2% and 97.0%, respectively, whereas its positive and negative predictive values were 97.1% and 96.1%. CEUS accuracy was 96.6%, higher than that of US (72.0%), Doppler US (70.0%), AFP levels (65.7%), combined US and Doppler US (70.0%) and combined US and AFP levels (90.3%). The differences between US and CEUS were statistically significant (p<0.05).

Conclusions

CEUS can characterise focal liver lesions with 96.6% accuracy, a value higher than US, Doppler US, AFP levels, combined US and AFP levels and combined US and Doppler US. CEUS should therefore be used to characterise focal liver lesions detected during HCC surveillance of cirrhotic patients.     

Radio-frequency ablation of VX2 rabbit tumors: assessment of completeness of treatment by using contrast-enhanced harmonic power Doppler US

PURPOSE: To assess contrast material-enhanced harmonic power Doppler and fundamental color Doppler ultrasonography (US) in the detection of residual viable tumor tissue after radio-frequency (RF) ablation in tumors embedded in fat. MATERIALS AND METHODS: Twenty-eight VX2 tumors were implanted into the retroperitoneum of 14 rabbits. Tumors were examined with contrast-enhanced fundamental color Doppler US and harmonic power Doppler US before and 10 minutes after RF ablation. Saline-enhanced RF ablation (30 mL/h) was performed over 10 minutes with 28-W RF power. Follow-up included repeat US examinations. Necropsies and histopathologic assessment were performed after detection of residual untreated tumor at US or 3 weeks after ablation. RESULTS: VX2 tumors reached a mean size of 21 mm +/- 9 (SD) (size range, 6-43 mm) 25 days after implantation. All tumors larger than 31 mm showed signs of central necrosis at US. Before ablation, intense vascularity was detected in all tumors with both contrast-enhanced US modes. Histopathologic assessment at the end of the follow-up period revealed local relapses due to incomplete ablation in 14 (50%) of 28 cases. Detection of residual tumor was missed in all cases with contrast-enhanced color Doppler US. Contrast-enhanced harmonic power Doppler US depicted residual flow in 12 of the 14 cases (sensitivity, 86%) in which local relapses occurred. There was a significant (P <.005, McNemar test) improvement in detection of residual tumor when the harmonic power Doppler mode was used. CONCLUSION: Contrast-enhanced harmonic power Doppler US has greater sensitivity than contrast-enhanced color Doppler US for detecting residual VX2 tumor following ablation. Therefore, contrast-enhanced harmonic power Doppler US may be a useful additional method for the detection of residual tumors after RF ablation.