Renal Perfusion Image Using Harmonic Ultrasound with Microbble Contrast Agent: Preliminary Study

PURPOSE: To compare, in terms of their feasibility and normal range, 99mTc-DTPA renal perfusion imaging and renal perfusion imaging using harmonic ultrasound (US) with a microbubble contrast agent for the evaluation of renal perfusion after renal transplantation. MATERIALS AND METHODS: During a six-month period, thirty patients who had received a renal transplant underwent both 99mTc-DTPA renal perfusion imaging and renal perfusion imaging using harmonic US with a microbubble contrast agent. Sonographic renal perfusion images were obtained before and after a bolus injection of the microbubble contrast agent LevovistTM (SH U 508A; Schering AG, Berlin, Germany) every 3 seconds for 3 minutes. Sonographic renal perfusion images were converted into a renal perfusion curve by a computer program and Tpeak of the curve thus obtained was compared with that of the 99mTc-DTPA curve. RESULTS: Average Tpeak of the 99mTc-DTPA renal perfusion curve was 16.2 seconds in the normal group and 39.6 seconds in the delayed perfusion group, while average Tpeak of the sonographic renal perfusion curve was 23.7 seconds and 46.2 seconds, respectively. Tpeak of the sonographic renal perfusion curve showed a good correlation with that of the 99mTc-DTPA curve (correlation coefficient=0.8209; p=0.0001). The cut-off value of Tpeak of the sonographic renal perfusion curve was 35 seconds (sensitivity=90%, specificity=95%). CONCLUSION: In patients who have received a renal transplant, the findings of renal perfusion imaging using harmonic US with a microbubble contrast agent show close correlation with those of 99mTc-DTPA renal perfusion imaging. The optimal cut-off value of Tpeak of the sonographic renal perfusion curve was 35 seconds.

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.

Unusual Renal Tuberculosis Manifested as an Isolated Renal Mass in an Immunocompromised Patient: A Case Report

Renal tuberculosis commonly involves the urinary tract and results in multifocal fibrosis and stricture. Rarely, it presents as a renal mass with or without urinary tract abnormality. The radiologic features of this rare pseudotumor have not been sufficiently described in the previous literature, and we now report a case of tuberculosis presenting as an isolated renal mass and multiple hepatic nodules without evidence of associated urinary tract abnormality. The condition mimicked malignant neoplastic disease and occurred in a patient who had undergone chemotherapy for leukemia.

Imaging Findings of Xanthogra nulomatous Pyelonephritis

PURPOSE: To define the imaging patterns of xanthogranulomatous pyelonephritis (XGP). MATERIALS AND METHODS: The demographic, clinical, and imaging findings of 21 cases of pathologically proven XGP in 20 patients (bilateral in one) were evaluated. The findings of ultrasonography and CT were retrospec-tively evaluated with regard to distribution and extent of the disease, kidney size, the presence of calculi, hy-dronephrosis, and renal function. The findings were assessed by two radiologists, who established a consen-sus. Imaging and pathologic findings were compared. RESULTS: Sixteen of the 20 patients were female, and 19 were adults. Their age ranged from 3 to 61 (mean, 45) years. In all patients except one, the disease was unilateral (right: left=13:16). In one patient, XGP was bilater-al, and there were thus 21 cases. Seventeen (81%) of these were diffuse, and four (19%) were focal; extrarenal extension occurred in 13 cases (62%), among which ipsilateral pleural effusion was noted in two. The kidney was enlarged diffusely in 12 cases (57%), and focally in three (14%); urinary calculi were present in 16 cases (76%), with staghorn calculi in four of these; and hydronephrosis occurred in 17 (81%). Impairment of ipsilat-eral renal function was noted in 13 cases (62%). Clinical findings of inflammation such as fever, pyuria, bac-teriuria, or leucocytosis were noted in all patients. CONCLUSION: In addition to nephromegaly, renal function impairment, and urinary obstruction due to calculi, which are typical features of XGP, the condition may also show variable imaging findings. If the images ob-tained in the case of a middle-aged woman with clinical findings of urinary infection are atypical, we believe that XGP should be included in the differential diagnosis.

Hyperechogenicity of Renal Medulla and Urinary Bladder in Normal Neonates: Clinical Significance

PURPOSE: To evaluate the clinical significance of hyperechogenicity of the renal medulla and urinary bladder in normal neonates. MATERIALS AND METHODS: We investigated 31 clinically normal neonates, including one post-term, 16 pre-term, and 14 full-term babies, in whom hyperechogenicity of the renal medulla or urinary bladder was seen on ini-tial sonograms. All neonates underwent sonography while aged between 1 and 21 (mean: 2.5)days. For 14, fol-low-up sonography was performed 2-20 (mean : 6.8) days later. Eighteen neonates also underwent urinalysis, and two underwent a bacteriologic examination. RESULTS: Initial sonograms revealed (hyperechogenicity in the renal medulla (n=28) and urinary bladder (n=12). Twenty-five neonates were aged less than one week, four were aged 1-2 weeks, and two were aged 2-3 weeks. Urinalysis showed that six neonates were erythrocyte-positive (+/-:1, +1:4, +4:1), two were protein-pos-itive (+/-:2), and the others were negative. In all cases the results of bacteriologic study were negative. Follow-up sonography revealed that the hyperechogencity of renal medulla had regressed (n=12) or decreased (2), and that of the urinary bladder had regressed (n=4). CONCLUSION: In clinically normal neonates, hyperechogenicity of the renal medulla and urinary bladder was mostly visualized within the first week of life, and on follow-up sonography was seen to have regressed or decreased.

Effectiveness of MR Urography in the Evaluation of Kidney which Failed to Opacify during Excretory Urography: Comparison with Ultrasonography

OBJECTIVE: The purpose of this study was to compare the effectiveness of MR urography (MRU) with that of ultrasonography (US) in the evaluation of urinary tract when this failed to opacify during excretory urography (EXU). MATERIALS AND METHODS: Twelve urinary tracts in 11 patients were studied. In each case, during EXU, the urinary system failed to opacify within one hour of the injection of contrast media, and US revealed dilatation of the pelvocalyceal syytem. Patients underwent MRU, using a HASTE sequence with the breath-hold technique; multi-slice acquisition was then performed, and the images were reconstructed using maximal intensity projection. Each set of images was evaluated by three radiologists to determine the presence, level, and cause of urinary tract obstruction. RESULTS: Obstruction was present in all twelve cases, and in all of these, MRU accurately demonstrated its level. In this respect, however, US was successful in only ten. The cause of obstruction was determined by MRU in eight cases, but by US in only six. In all of these six, MRU also successfully demonstrated the cause. CONCLUSION: MRU is an effective modality for evaluation of the urinary tract when this fails to opacify during EXU, and appears to be superior to US in demon-strating the level and cause of obstruction.

Power Doppler Ultrasound Findings of Renal Infarct after Experimental Renal Artery Occlusion: Comparison withSpiral CT

PURPOSE: To evaluate the efficacy of power Doppler ultrasonography (PDUS) in depicting renal infarction inrabbits during experimental renal segmental arterial occlusion, and to compare the results with those of CTscanning. MATERIALS AND METHODS: In 28 rabbits weighing 2.5-4kg, the segmental renal artery was occluded throughthe left main renal artery by embolization with Ivalon (Nycomed, Paris, France). Power Doppler ultrasonography andspiral CT scanning were performed before and at 2, 5, 8, 15, and 24 hours, and 3 and 7 days after occlusion of thesegmental renal artery. The location of infarcted areas and collaterals, as seen on PDUS and CT scans, wasevaluated by two radiologists. RESULTS: In all cases, as seen on power Doppler ultrasonography, infaretedareas-when compared with normal parenchyma, clearly demonstrated wedge-shaped perfusion defects in the kidney. Thelocation of the lesion closely corresponded to the location seen during CT scanning. After renal arterialocclusion, transiently congested capsular arteries, which were named 'capsular sign', were seen in 63% ofrabbits in the two and five-hour groups. No significant cortical rim sign was demonstrated on power Dopplerultrasonography, though it was noted on spiral CT at 15 and 24 hours, and 3 and 7 days after renal arterialocclusion. CONCLUSION: Power Doppler ultrasonography was useful for the diagnosis of renal infarction. Congestedcapsular artery seen in the early stage of renal infarction might be a characteristic finding of this condition,as seen on power Doppler ultrasonography.

The Value of Intrarenal Resistive Index in Autosomal Dominant Polycystic Kidney Disease

PURPOSE: The purpose of this study was to determine the value of the intrarenal resistive index (RI),measured by Doppler sonography, in order to assess intrarenal vascular resistance in autosomal dominant polycystickidney disease (ADPKD) patients. MATERIALS AND METHODS: In 26 patients with ADPKD, RI was measured by Dopplersonography and correlated with the presence of hypertension, renal function (creatinine clearance) and anatomicalrenal severity index (RSI), thus indicating renal morphologic abnormalities during B-mode sonography . RESULTS:RI was significantly higher in 18 hypertensive ADPKD patients (0.64+/-0.65) (Mean+/-1SD; range: 0.52-0.74) than ineight normotensive patients (0.59+/-0.50) ( 0.48-0.64) (p<0.05). Statistically significant inverse correlation wasfound between RI values and creatinine clearance (r=-0.45, p<0.05), and statistically significant correlation wasfound between RI values and RSI, indicating the degree of renal parenchymal involvement. CONCLUSION: RIcorrelates with the development of hypertension, renal function and renal morphologic abnormality scoring by RSIduring B-mode Doppler sonography, and measured in this way may thus be used to assess renal vaseular resistance inADPRD patients.

Dupplex Doppler Sonography in Patients with Medical Renal Diseases: Correlation with Clinical and Histopathologic Findings

PURPOSE: To compare the RI (resistive index) of renal artery with serum creatinine level and histological change in 50 patients with renal parenchymal disease. MATERIALS AND METHODS: To measure RI in each patient, Doppler studies were performed three times in each kidney at the level of the interlobar arteries, and the average value of RI was taken. The study was performed 1-3 days after renal biopsy and the time interval between blood sampling for serum creatinine and duplex study was also 1-3 days. The RI of patients with renal disease was also correlated with patient's age, sex and serum creatinine level, and RI was also correlated with the degree of severity of glomerular, interstitial, and vascular change in the kidneys. Statistical analysis was performed using Student's t test and Pearson's correlation method. RESULTS: The RI of the normal control and renal disease group was 0.566+/-0.037 and 0.584+/-0.038, respectively with no statistical significance (p=0.444). In the group with renal disease, there was no significant correlation between RI and a patient's age, sex, and serum creatininelevel (p>0.05). RI was not significantly different between predominantly glomerular disease (n=45) and nonglomerular or mixed disease (n=5) (p=0.558), and did not correlate with the severity of glomerular sclerosis, interstitial fibrosis, or atherosclerosis (p>0.05). CONCLUSION: The authors conclude that RI is not helpful for the diagnosis and differential diagnosis of renal parenchymal diseases and does not correlate with serum creatinine levels. In order to define the role of the RI, further clinical experience with more cases is required.

CT Findings of Acute Pyelonephritis and Clinical Correlation

PURPOSE: To evaluate postcontrast CT findings of acute pyelonephritis and correlate these with clinical findings and severities. MATERIALS AND METHODS: We retrospectively reviewed the medical records and CT scans of 50 patients with abnormal CT findings among 52 patients of acute pyelonephritis whose postcontrast CT scans had been examined. Fifty cases of acute pyelonephritis were classified into three subgroups on the basis of postcontrast CT findings : Group I (n=20, 40%) wedge-shaped lesions; Group II (n=13, 26%) mass-like lesions; Group III (n=17, 34%) renal abscess formation. In each group, clinical findings and severity were analyzed and correlated with CT findings. The results were statistically analyzed. RESULTS: Although mean values of clinical parameters of group I were lower than those of group II and III with regard to all clinical parameters (including maximal temperature and duration of fever, flank pain, leukocytosis, and admission period), there was no statistically significant correlation among the three groups (p>0.05). All cases were successfully treated with antibiotics only, despite the high rate of abscess formation (34%). CONCLUSION: Acute pyelonephritis spans a continuum of CT findings of varying severity from wedge-shaped or mass-like lesions to multifocal abscesses ; postenhanced CT scan shows high sensitivity (96%) in the detection of acute pyelonephritis. Although the clinical course of groups of mass-like lesions and abscess formation was longer and more severe than that of wedge-shaped lesions, there was no statistically significant clinicoradiologic correlation among the three groups.

Evaluation of Renal Resistive Index in Cirrhotic Patients for Predicting the Hepatorenal Syndrome

PURPOSE: To evaluate the usefulness of renal resistive index(RI) in patients with liver cirrhosis as an indicator for predicting hepatorenal syndrome. MATERIALS AND METHODS: Renal RIs of thirty cirrhotic patients were analyzed using the gray-scale and Doppler ultrasonograms. As a control group, eight normal subjects were alsoincluded. Renal RIs were measured at three sites of interlobar or arcuate arteries of both kidneys. The patients were divided into three groups (A, B, or C) according to the Child-Turcotte-Pugh classification and their serum BUN and creatinine levels were compared. We determined whether RIs of normal controls differed from those of cirrhotic patients or whether RIs of cirrhotic patients correlated with the Child-Turcotte-Pugh classification or BUN and creatinine levels. RESULTS: Mean RIs(0.63 +/-0.03) of normal subjects were statistically different from those(0.67 +/-0.05) of cirrhotic patients(P=0.009). RIs of group A(n=6), B(n=9) and C(n=15) were 0.65 +/-0.03,0.65 +/-0.04 and 0.70 +/-0.04, respectively. The ANOVA test revealed statistically significant differences between the three groups(F ratio=4.472, P=0.021). RIs did not correlate with BUN or creatinine levels. CONCLUSION: RI could be used as an index for predicting hepatorenal syndrome before the renal function becomes impaired.

Morphological Variation of the Kidney Secondary to Junctional Parenchyma on Ultrasound

PURPOSE: To evaluate the prevalance of morphological variation of the kidney secondary to junctional parenchyma, as well as to analyze the ultrasonographic features of junctional parenchyma. MATERIALS AND METHODS: Two hundred and eighty two kidneys of 141 patient without clinical or radiologic evidence of renal disease were prospectively analysed using ultrasound. In all patients, ultrasonograms were obtained in sagittal, coronal and transaxial planes. The kidney was considered to have morphological variation if the ulrasonogram demonstrated junctional parenchymal defect or line ; those showing such variation were classified as one of three types :continuous, discontinuous, or junctional parenchymal line or defect without junctional parenchyma. The prevalance and ultrasonographic features of the kidneys were evaluated. RESULTS: Morphological variation was noted in 71 cases(25%). the continuous type accounted for 54% of these, the discontinuous type for 38%, and junctional parenchymal defect or line without junctional parenchyma for 8%. In all cases, junctional parenchyma was located approximately at the junction of the upper and middle third of the kidny, and had the same echogenecity as the renal cortex. CONCLUSION: An understanding of the morphological variation of the kidney resulting from junctional renal parenchyma would be helpful in differentiating pseudo tumor from true renal neoplasm.