Reliability of ADC values in recognition of renal changes produced by extracorporeal shock wave lithotripsy (ESWL)

Objectives

To evaluate the reliability of diffusion-weighted imaging (DWI) in evaluating kidney changes after extracorporeal shock wave lithotripsy (ESWL) treatment for kidney stones.

MR perfusion imaging of the kidney pre- and post-dipyridamole stress

Animal studies have demonstrated that renal MR contrast enhancement depends on the timing of image acquisition. Limited human studies have demonstrated effects of dipyidamole (DP) on total renal perfusion. This study assessed the effect of DP on total and regional renal perfusion using gated perfusion MRI for patients undergoing DP stress. Five subjects with no evidence of renal ischemia were examined at rest and after DP stress. Rest MRI images in the left kidney were acquired using electrocardiogram (ECG)-gated MR: turbo fast low-angle shot (FLASH); echo time (TE) = 12, repetition time (TR) = 6. flip angle = 12, inversion time (TI) = (100) 10 to 45 seconds after injection of gadopentetate dimeglumine. Stress was induced in the MRI scanner (DP, .56 mg/kg over 4 minutes) followed by stress MRI after a second bolus of gadopentetate dimeglumine in the same position and identical time intervals. MR signal in the whole left kidney and renal medulla and cortex pre- and post-DP demonstrated a 70% depression of total renal perfusion with relative preservation of cortical perfusion at the expense of medullary perfusion. Post-DP MR images demonstrated a decrease in cortical perfusion with an additional 29% depression of medullary perfusion (P < .001) with respect to cortical perfusion. Turbo FLASH MRI can provide adequate time and spatial resolution to demonstrate changes in renal perfusion. Depression of renal medullary perfusion after DP appears to be caused by the intrarenal effect of DP and may have clinical impact.     

Blood pressure changes after extracorporeal shock wave nephrolithotripsy: prediction by intrarenal resistive index

In order to identify a high-risk group for the development of arterial hypertension after extracorporeal shock wave nephrolithotripsy (ESWL), we correlated the increase in renovascular resistance induced by ESWL in 79 normotensive patients with changes in arterial blood pressure occurring 20 (+-3) months after therapy. Renal vascular resistance was measured as resistive index (RI) by duplex Doppler sonography in both kidneys. Mean RI before treatment was 0.620±0.035 (SD). After treatment, we observed a significant and age-dependent increase in the RI in the treated kidney to 0.673 ± 0.06. Of the patients with a post-ESWL RI> 0.690, 39% developed hypertension. Posttherapy RI values surpassing 0.690 showed a 0.8 sensitivity and a 0.7 specificity in predicting arterial hypertension. Intrarenal Doppler ultrasound (US) is useful to find the high-risk group for arterial hypertension after ESWL. Correspondence to: R. Knapp     

Kidney changes after extracorporeal shock wave lithotripsy: appearance on MR imaging

The occurrence of changes in the kidneys after extracorporeal shock wave lithotripsy (ESWL) was evaluated with magnetic resonance (MR) imaging in 34 patients, utilizing T1-weighted spin-echo pulse sequences. Five of the 34 patients underwent bilateral ESWL therapy before MR imaging. Of the 39 kidneys studied, 29 (74%) showed one or more changes on MR imaging: subcapsular or perinephric fluid (n = 10), focal (n = 16) or diffuse (n = 8) loss of the corticomedullary junction (CMJ), and focal areas of increased (n = 7) or decreased (n = 3) signal intensity. The CMJ changes were more prominent with increasing numbers of shock waves administered during the procedure. These relatively subtle changes detected on MR imaging may not be apparent with other imaging techniques. The long-term clinical significance of these findings is not yet known, although no apparent serious renal pathologic condition was detected.     

Renal morphology and function immediately after extracorporeal shock-wave lithotripsy

The acute effects of extracorporeal shock-wave lithotripsy (ESWL) on morphology and function of the kidney were evaluated by excretory urography, quantitative radionuclide renography (QRR), and magnetic resonance imaging (MRI) in 33 consecutive patients. Excretory urograms demonstrated an enlarged kidney in seven (18%) of 41 treatments and partial or complete obstruction of the ureter by stone fragments after 15 (37%) of 41 treatments. Total effective renal plasma flow (ERPF) was not changed after ESWL, but the percentage ERPF of the treated kidney was decreased by more than 5% in 10 (30%) of 33 cases. QRR images showed partial parenchymal obstruction in 10 (25%) of 41 treated kidneys and total parenchymal obstruction in 9 (22%). MRI disclosed one or more of the following abnormalities in 24 (63%) of 38 treated kidneys: (1) loss of corticomedullary differentiation, (2) perirenal fluid, (3) subcapsular hematoma, (4) hemorrhage into a renal cyst, and (5) unexplained abnormalities. Treated kidneys were normal by all three imaging methods in 26% and abnormal by one or more tests in 74% of cases. The morphologic and functional changes are attributed to renal contusion resulting in edema and extravasation of urine and blood into the interstitial, subcapsular, and perirenal spaces.     

Renal changes from extracorporeal shock-wave lithotripsy: evaluation using Doppler sonography

In this study, duplex Doppler sonography was used to evaluate flow changes within renal intraparenchymal vessels induced by extracorporeal shock-wave lithotripsy (ESWL). We have examined 20 patients with caliceal stones before, 1 h and 24 h after ESWL. Doppler waveforms were obtained both from arteries located near the stone and at least at 3 cm from it, and resistive index (RI) measured. A statistically significant increase of the RI (0.079 ± 0.039 mean increase; P < 0.001) was detected 1 h after ESWL in vessels located near the stone. After 24 h, RI tended to normalize (0.056 ± 0.037 mean decrease; P < 0.001). The residual difference (0.022 ± 0.043; P = 0.399) between mean RI values obtained near the stone before and 24 h after ESWL was mainly due to persistent elevated RI values in three patients with ESWL induced hydronephrosis. No significant RI changes were recognized in intraparenchymal vessels located far from the stone. In all patients, Doppler alterations were not associated with morphologic changes of renal parenchyma. Correspondence to: L. E. Derchi     

Magnetic resonance imaging of the kidneys

A study of the magnetic resonance imaging (MRI) appearances of the kidneys in six normal volunteers and 52 patients is reported. Corticomedullary differentiation was seen with the inversion-recovery (IR 1400/400) sequence in the normal volunteers and in patients with functioning transplanted kidneys and acute tubular necrosis. Partial or total loss of corticomedullary differentiation was seen in glomerulonephritis, acute and chronic renal failure, renal artery stenosis, and transplant rejection. The T1 of the kidneys was increased in glomerulonephritis with nephrotic syndrome, but the T1 was within the normal range for renal medulla in glomerulonephritis without nephrotic syndrome, renal artery stenosis, and chronic renal failure. A large staghorn calculus was demonstrated with MRI, but small calculi were not seen. Fluid within the hydronephrosis, simple renal cysts, and polycystic kidneys displayed very low signal intensity and long T1 values. Evidence of recent hemorrhage into cysts was seen in polycystic kidneys. Tumors displayed varied appearances. Hypernephromas were shown to be hypo- or hyperintense with the renal medulla on the IR 1400/400 sequence. After intravenous injection of gadolinium-DTPA, there was marked decrease in the tumor T1.     

Massive retroperitoneal haemorrhage after extracorporeal shock wave lithotripsy (ESWL)

A 76-year-old male suffering from nephrolithiasis developed a shock syndrome 5 days after extracorporal shock wave lithotripsy (ESWL). CT scan of the abdomen showed massive haemorrhage around the right kidney. Although nephrectomy was performed immediately, the haemorrhage could not be controlled. Numerous units of erythrocytes were transfused, but the patient died. The autopsy revealed massive retroperitoneal haemorrhage around the right kidney. The kidney showed a subcapsular haematoma and a rupture of the capsule. The right renal artery was dissected. The inferior vena cava was lacerated. Accordingly, a hemorrhagic shock as the cause of death was determined, which might mainly have resulted from the laceration of the inferior vena cava due to ESWL. ESWL seems to be a relatively non-invasive modality, but one of its severe complications is perirenal hematoma. The injuries of the blood vessels might have been caused by excessive shock waves. Subsequently, anticoagulation therapy had been resumed 3 days after EWSL, which might have triggered the haemorrhage. Physicians should note that a haemorrhage after an ESWL can occur and they should pay attention to the postoperative management in aged individuals especially when they are under anticoagulation therapy.     

USPIO-enhanced MR imaging of macrophage infiltration in native and transplanted kidneys: initial results in humans

The purpose of this study was to evaluate the detection and characterization of macrophage infiltration in native and transplanted kidneys using ultrasmall superparamagnetic iron oxide particles (USPIO). Among 21 patients initially enrolled, 12 scheduled for renal biopsy for acute or rapidly progressive renal failure (n = 7) or renal graft rejection (n = 5) completed the study. Three magnetic resonance (MR) sessions were performed with a 1.5-T system, before, immediately after and 72 h after i.v. injection of USPIO at doses of 1.7–2.6 mg of iron/kg. Signal intensity change was evaluated visually and calculated based on a region of interest (ROI) positioned on the kidney compartments. Histological examination showed cortical macrophage infiltration in four patients (>5 macrophages/mm²), two in native kidneys (proliferative extracapillary glomerulonephritis) and two in transplants (acute rejection). These patients showed a 33 ± 18% mean cortical signal loss on T2*-weighted images. In the remaining eight patients, with <5 macrophages/mm², there was no cortical signal loss. However, in three of these, presenting with ischemic acute tubular necrosis, a strong (42 ± 18%) signal drop was found in the medulla exclusively. USPIO-enhanced MR imaging can demonstrate infiltration of the kidneys by macrophages both in native and transplanted kidneys and may help to differentiate between kidney diseases.     

Dynamic scintigraphy of the kidney using 99m-Tc-DTPA before and after extracorporeal shock wave lithotripsy

The results of dynamic scintigraphy of the kidneys using 99mTc-DTPA that is glomerular radiopharmaceutic in patients before and after ESWL (extracorporeal shock wave lithotripsy) are presented. Investigation was performed in 22 patients--in 8 patients immediately before ESWL, 7 days and 3 months later, and in 14 patients before and 7 days after ESWL. The time alteration of the achievement of the maximal values of radiorenographic curve obtained by dynamic scintigraphy (Tmax), as the alteration of separate clearance (SCI) counted as an integral below the other phase of renographic curve. No significant differences were observed in the values of separate clearance before and after ESWL, while Tmax was significantly reduced 3 months after ESWL (p < 0.05). Our results indicated the improvement of glomerular filtration of the kidneys 3 months after ESWL (faster passing of DTPA through the treated kidney).     

Dynamic magnetic resonance imaging in the assessment of chronic medical nephropathies with impaired renal function

We examined the value of dynamic magnetic resonance imaging (MRI) in chronic renal disease with renal insufficiency. In 33 consecutive patients (21 vascular nephropathy, 12 glomerular nephropathy) MRI was performed using a 1.5-T unit and a body coil, with SE T1-weighted (TR/TE = 600/19 ms) and dynamic TFFE T1-weighted sequences (TR/TE = 12/5 ms, flip angle = 25 °) after manual bolus injection (via a cubital vein) of 0.1 mmol/kg Gd-DTPA-BMA. Morphological evaluation was performed in unblinded fashion by three radiologists, evaluating renal size, cortical thickness, and corticomedullary differentiation. Functional analysis was performed by one reviewer. Time-signal intensity curves, peak intensity value (P), time to peak intensity (T), and the P/T ratio were obtained at the cortex, medulla, and pyelocaliceal system of each kidney. The relationship of these parameters to serum creatinine and with creatinine clearance was investigated. A good correlation between morphological features of the kidneys and serum creatinine values was found. Morphological findings could not distinguish between vascular and glomerular nephropathies. A statistically significant correlation (P <0.01) between cortical P, cortical P/T, medullary P, and serum creatinine and creatinine clearance was found. A significant correlation (P <0.01) was also found between cortical T, medullary P/T, T of the excretory system, and creatinine clearance. The cortical T value was significantly higher (P <0.01) in vascular nephropathy than in glomerular nephropathy. Thus in patients with chronic renal failure dynamic MRI shows both morphological and functional changes. Morphological changes are correlated with the degree of renal insufficiency and not with the type of nephropathy; the functional changes seem to differ in vascular from glomerular nephropathies. Received: 5 March 1999; Revised: 28 June 1999; Accepted: 9 August 1999     

Microvascular changes in rabbit kidneys after extracorporeal shock wave treatment

Concerns about the safety of extracorporeal shock wave lithotripsy include the risk of vascular damage and the genesis of hypertension. We evaluated gross specimens and barium microangiograms of the right kidneys of 14 rabbits exposed to shock waves; the untreated left kidneys served as controls. Six rabbits were assessed immediately after shock wave treatment, whereas the other eight rabbits had the same procedure 3 months later. All six acute phase animals showed microangiographic changes indicative of shock wave trauma, including cortical, subcapsular, and medullary extravasation of barium and patchy loss of efferent vessels. No significant vascular abnormalities were seen in the control kidneys. All kidneys treated from the animals that had delayed microangiography showed macroscopic evidence of fibrotic capsular thickening and parenchymal scarring. Microscopically, there was crowding of glomeruli and areas of avascularity. In this model, shock waves damaged the cortical circulation and resulted in persistent alterations of the microvasculature that potentially could be responsible for the abnormal secretion of renin.     

Complications of the treatment of renal calculi by extracorporeal lithotripsy. Prospective evaluation of 80 treated kidneys

The acute effects of extracorporeal shock wave lithotripsy (ESWL) on morphology and function of the kidney were prospectively evaluated by abdominal radiography, ultrasonography and contrast-enhanced computed tomography, in 80 treated kidneys. Two types of complications were demonstrated: 1. Obstruction of the ureter by stone fragments in 25% of cases. Relief procedures became necessary in 5 patients (6% of the 80 cases). 2. Limited injuries of the kidney and perirenal spaces in 44% of cases: parenchymatous abnormalities 17.5%; subcapsular hematoma 12.5%; perirenal fluid collection 24%. No treatment was necessary and morphologic abnormalities disappeared in one or two months post-ESWL. Severe ureteral obstruction after ESWL seems to be related to stone size. No definitive evidence that kidney's injury was related to the number of shock waves applied to the kidney was found.     

Functional evaluation of transplanted kidneys in normal function and acute rejection using BOLD MR imaging

In this study, we evaluated a large number of subjects using BOLD MRI to provide more information about oxygen metabolism in the normal function of transplanted kidneys and to distinguish acute graft rejection from normal function kidneys. This study included 122 subjects (20 volunteers, 72 patients with normal functioning transplants, and 21 patients with acute rejection), and 9 patients had normal function grafts received examination while grafts dysfunction occurred within 6 months during the follow-up. The R2 (1/s) values in the cortex and medulla as well as the R2 ratio of the medulla to cortex (R2 ratio of M/C) were recorded. The R2 values of the medulla were higher than those of the cortex in the normal function group and the volunteers which have a steep R2 ratio of M/C. All the R2 values in the acute rejection group were lower than those in the normal function grafts group (P<0.001). Moreover, in the 9 patients as normal function, the R2 values of the cortex and medulla were different from the normal function grafts, which was lower in 5 patients and was higher in the 4 remaining patients. Conversely, the R2 ratios of M/C of the 9 patients were similar to those in the normal function group. BOLD MRI shows that decreased R2 values of the cortex and medulla and R2 ratio of M/C suggest acute renal graft rejection; furthermore, a steep R2 ratio of M/C (>1.1) is an important reason for keeping clinical normal function.     

Complications of renal extracorporeal shock wave lithotripsy reviewed

Renal extracorporeal shock wave lithotripsy (ESWL) is a noninvasive and effective method for the treatment of a variety of urinary tract calculi with significantly lower morbidity than both surgical procedures for stone removal (pyelolithotomy/ureterolithotomy) and percutaneous nephrostolithotomy. Though significant, severe complications are rare, ESWL therapy can result in a wide spectrum of tissue injury. This article serves to review the currently known complications of ESWL, which radiologists may encounter, providing an understanding of the potential effects of shock waves on body organs and the resultant functional and morphologic changes that may result.     

Parenchymal abnormalities associated with developmental venous anomalies

Introduction To report a retrospective series of 84 cerebral developmental venous anomalies (DVAs), focusing on associated parenchymal abnormalities within the drainage territory of the DVA. Methods DVAs were identified during routine diagnostic radiological work-up based on magnetic resonance imaging (MRI) (60 cases), computed tomography (CT) (62 cases) or both (36 cases). Regional parenchymal modifications within the drainage territory of the DVA, such as cortical or subcortical atrophy, white matter density or signal alterations, dystrophic calcifications, presence of haemorrhage or a cavernous-like vascular malformation (CVM), were noted. A stenosis of the collecting vein of the DVA was also sought for. Results Brain abnormalities within the drainage territory of a DVA were encountered in 65.4% of the cases. Locoregional brain atrophy occurred in 29.7% of the cases, followed by white matter lesions in 28.3% of MRI investigations and 19.3% of CT investigations, CVMs in 13.3% of MRI investigations and dystrophic calcification in 9.6% of CT investigations. An intracranial haemorrhage possibly related to a DVA occurred in 2.4% cases, and a stenosis on the collecting vein was documented in 13.1% of cases. Parenchymal abnormalities were identified for all DVA sizes. Conclusion Brain parenchymal abnormalities were associated with DVAs in close to two thirds of the cases evaluated. These abnormalities are thought to occur secondarily, likely during post-natal life, as a result of chronic venous hypertension. Outflow obstruction, progressive thickening of the walls of the DVA and their morphological organization into a venous convergence zone are thought to contribute to the development of venous hypertension in DVA. Presented at the 44th Annual Meeting of the American Society of Neuroradiology, San Diego, Calif., USA, May 1–5, 2006.     

MR灌注成像在正常肾和肾脏疾病中的应用价值

目的 探讨正常肾脏及常见肾脏疾病MR灌注加权成像(PWI)的主要表现特征和临床应用价值.方法 搜集共31例患者行MR PWI,其中9例非泌尿系统疾病患者作为正常肾对照组,肾癌14例,肾囊肿6例,肾结核2例.31例均行冠状面常规T1WI、T2WI与PWI.原始图像经工作站处理后获得灌注曲线及各功能图像,比较正常肾脏及病变部位的时间-信号强度曲线、血容量(RBV)、血流量(RBF)、平均通过时间(MTT)、达峰值时间(TTP)及相应灌注功能图像.正常肾脏灌注参数(RBV、RBF、MTT和TTP)的相对值通过左肾/右肾获得,异常肾脏灌注参数通过病变组织/对侧同一部位肾组织获得.观察两组肾脏的血流灌注参数变化,并结合灌注图像对其病变组织的血流变化进行分析.对正常对照组左、右肾和正常肾皮、髓质各灌注参数的比较采用t检验;对异常肾与正常肾各灌注参数的比较行q检验.结果 正常肾脏皮质的相对RBV(1.33±0.08)和RBF(1.44 ±0.09)均明显大于髓质相对RBV(0.58 ±0.05)和相对RBF(0.78 ±0.13),差异均有统计学意义(t值分别为9.2241和5.0336,P值均＜0.01);肾脏皮质相对MTT(1.11±0.08)和相对TTP(1.04 ±0.06)与髓质相对MTT(0.97±0.04)和相对TTP(0.94±0.03)差异无统计学意义(t值分别为2.2551和2.2613,P值均＞0.05).肾癌相对RBF(1.35±0.34)明显高于正常肾脏组织相对RBF(1.02±0.06)(q=3.0882,P＜0.01).结论 PWI可以测量正常肾组织与病理情况的血液动力学变化,在肾功状态变化和疾病的鉴别诊断方面具有较高的应用价值.     

The kidney in paroxysmal nocturnal haemoglobinuria: MRI findings

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, acquired stem-cell disorder characterized by defective haematopoiesis, which results in an increased sensitivity of the erythrocytes to complement-mediated intravascular haemolysis. Renal damage is infrequent but can produce chronic renal failure due cortical deposits of haemosiderin and microvascular thrombosis. MRI provides characteristic images of the kidneys that enable haemosiderin deposition to be diagnosed; in PNH, MRI typically shows reversed renal cortex-medulla differentiation on T(1) weighted images and substantial loss of cortical signal intensity on both T(1) and T(2) weighted images. We describe the MRI findings of renal cortical haemosiderosis occurring in four patients with PNH.     

肾功能衰竭大鼠超顺磁性氧化铁标记骨髓间充质干细胞肾脏移植MR活体示踪的研究

目的应用磁性氧化铁纳米粒子和多聚左旋赖氨酸（poly-L-lysine，PLL）的偶联物Fe2O3-PLL标记大鼠骨髓间充质干细胞（MSCs），MR活体示踪经肾动脉移植入肾功能衰竭（简称肾衰）大鼠肾脏的标记细胞。方法制备Fe2O3-PLL，分离、纯化并培养大鼠骨髓MSCs，Fe2O3-PLL标记细胞，普鲁士蓝染色显示细胞内铁。肌内注射甘油所致肾衰的大鼠分为2组，分别经左肾动脉移植入标记细胞（6只）和未标记细胞（5只），移植后即刻及第1、3、5、8天应用MRI对移植细胞进行活体示踪，并与肾脏组织切片普鲁士蓝染色和HE染色对照。结果MSCs的Fe2O3-PLL标记率近100％，普鲁士蓝染色显示蓝色铁颗粒位于MSCs胞质内。标记细胞移植后肾衰大鼠肾脏皮质区信号强度明显下降，T2＊WI信号改变最明显，而肾髓质及肾盂信号较细胞移植前无明显变化，信号改变随着时间的延长逐渐减轻一直持续到移植后第8天。组织学分析见绝大多数标记细胞分布于肾皮质肾小球内，与MRI信号改变区域基本一致。未标记细胞移植后未见肾脏信号改变。结论Fe2O3-PLL可以有效标记大鼠骨髓MSCs，临床应用型1．5T磁共振仪可对经肾动脉移植入肾衰大鼠肾脏的标记细胞进行初步活体示踪。     

Sonographic evaluation of renal stones treated by extracorporeal shock-wave lithotripsy

Real-time sonography was performed on 94 patients the day before and at 24 and 48 hr after extracorporeal shock-wave lithotripsy (ESWL) therapy. The ability of sonography to detect renal stones before ESWL, changes in the calculi after ESWL, and the occurrence of pre- and post-ESWL hydronephrosis was evaluated. Abdominal radiographs and linear renal tomography were used as the standard of comparison. Six other patients had sonography only either before or after ESWL. One hundred patients had a total 105 kidneys treated; 18 kidneys with more than three stones were not included. The other 87 kidneys had 102 stones evaluated by sonography before having ESWL; 66 stones (65%) were identified and 36 were not. Of those calculi not seen, 10 were less than or equal to 5 mm in diameter. Nineteen of the other 26 stones were in the ureter or at the ureteropelvic junction. Comparison of sonograms of 80 kidneys obtained before and after ESWL revealed no change in 37 (46%), more stones or fragments detected in 23 (29%), fewer stones or a change in location in 12 (15%), and an apparent decrease in the size of the original stone in eight (10%). Hydronephrosis was detected by pre-ESWL sonography in 16 kidneys (20%) and was noted to develop after ESWL in 20 (31%) of the 64 other kidneys. These results indicate that the ability of sonography to detect renal calculi is related not only to stone size but also to location. The clinical significance of pre- and post-ESWL hydronephrosis found by sonography must be considered in conjunction with the patient's symptoms, laboratory data, and other radiographic studies. Therefore, the routine use of sonography in the post-ESWL patient does not seem warranted.