Yasuhito Saito

Ten-Year Prospective Study on the Development of Renal Cell Carcinoma in Dialysis Patients

A prospective study was undertaken to investigate the development of renal cell carcinoma in dialysis patients. Three renal cell carcinomas were detected among 96 hemodialysis patients in 1979, and screening by computed tomographic (CT) scan was continued yearly until 1989. During this 10-year period, one renal cell carcinoma was found in the second year and another in the ninth year. Autopsy performed on seven of 19 patients who died showed one case of small clear cell carcinoma accompanying acquired cystic disease. In 33 males, kidneys were found to have enlarged 2.7 +/- 1.7 times over the 10-year follow-up due to acquired cysts, while no change in kidney volume was noted in 24 females. Native kidneys in nine of 12 patients who maintained functioning grafts were reduced in size. The patient with the largest kidney enlargement (11.5 times) died from retroperitoneal bleeding in 1989. These prospective study results suggest that both the incidence and prevalence of renal cell carcinoma in dialysis patients is high. Furthermore, major complications of acquired renal cystic disease seem to occur predominantly in males.

Delayed contrast enhancement in acute focal bacterial nephritis: CT features.

Computed tomography was performed in seven patients with acute pyelonephritis 6 h after the administration of contrast medium. Four patients revealed patchy wedge-shaped areas of contrast enhancement. The scans immediately after contrast medium administration showed decreased attenuation in these wedge-shaped areas. These results suggest that CT performed hours after contrast medium administration may reveal delayed enhancement in a significant number of patients with acute pyelonephritis.

Sex differences in acquired cystic disease of the kidney on long-term dialysis.

Acquired cystic disease of the kidney in chronic glomerulonephritic patients who had been on hemodialysis more than 3 years (4.5 +/- 1.2 years at the base line examination), were followed for 3.6 +/- 0.5 years (at the follow-up examination) by computed tomography (CT scan). The renal volume in the 25 male patients was significantly greater at the follow-up examination than at the base line examination. On the other hand, the renal volume in the 12 female patients was similar on both examinations. The enlargement of kidney volume more than twofold during the follow-up was seen in 9 of 25 male and none of 12 female patients. The grade of cystic transformation was increased in male patients during the follow-up period. These results indicate that sex-related endogenous substances might play a role in the pathogenesis of acquired cystic disease.

Renal cortex visualization and analysis of dynamic CT curves of the kidney.

Renal cortex visualization and dynamic renal computed tomography (CT) were carried out by bolus injection of contrast medium. In vivo renal cortex visualization showed that renal cortex volume and cortex thickness are both inversely correlated with age. The percentage volumes of cortex and columns of Bertin are correlated inversely in non renal-failure subjects. Percentage volumes of cortex tend toward low values in renal failure and status after renal transplantation. In analyzing dynamic renal CT curves, the corticomedullary junction time is a good index of mild impairment of renal function.

Evidence for Patchy Renal Vasoconstriction in Man: Observation by CT Scan

We report the first demonstration of patchy vasoconstriction of the kidney in man, together with temporary impairment of renal function. Observations were made by computerized tomography (CT scan). Such vasoconstriction might occur during the mild form or the recovery phase of acute renal failure.

Fifteen-Year Follow-Up of Acquired Renal Cystic Disease -A Gender Difference

In 1979, 96 patients who had undergone hemodialysis for a mean of 3 years and 4 months were entered into this study. This follow-up study revealed that the bilateral kidney volume significantly increased over 10 years in 33 male patients. Kidneys were found to have enlarged 2.7 times over the 10-year follow-up period. However, in 24 females kidney volume did not change over 10 years. This paper reports further results in 39 dialysis patients (21 males and 18 females) who were followed from the 10th to 15th year. In male patients, mean volume was 196 +/- 218 ml (mean +/- SD) at the 10th year and had significantly increased to 225 +/- 213 ml at the 15th year (p < 0.02). In female patients, mean kidney volume was 78 +/- 51 ml at the 10th year and had increased to 117 +/- 91 ml at the 15th year (p < 0.01). The enlargement in kidney volume during the recent 5 years was 1.26 +/- 0.39-fold in males and 1.43 +/- 0.45-fold in females. These rates did not significantly differ between males and females. During this recent 5-year period, there were no surgical cases due to renal cell carcinoma. Therefore, over the entire patient-time dialysis period, there were 6 renal cell carcinomas in 1,470 patient years. In conclusion, 10- to 15-year follow-up studies of kidney size revealed that the enlargement in the kidney due to acquired cysts persisted in male patients, but the rate of increase slowed after 13.0 years of hemodialysis, while the enlargement in the kidney in female patients became significant at 17.7 years of hemodialysis, revealing the slowly progressive nature of acquired cysts in women.

Dynamic computed tomography in acute renal failure: analysis of time-density curve.

An analysis of dynamic CT curves in 12 patients with acute renal failure was performed. An oliguric patient who demonstrates corticomedullary differentiation on CT images will develop diuresis within 4 days. A corti-coaortic junction time of more than 180 s associated with no differentiation between cortex and medulla is associated with prolonged oligoanuria. Impending diuresis is heralded by a corticoaortic junction time of less than 180 s. These preliminary results suggest that an analysis of dynamic CT curves in acute renal failure can predict the time of appearance of the diuretic stage.

Digital glomerular reconstruction in a patient with a sporadic adult form of glomerulocystic kidney disease

This study describes a sporadic adult form of glomerulocystic kidney disease in a 52-year-old man. To determine whether the aperture of the proximal tubule was stenosed or obstructed to clarify the pathogenesis of glomerular cyst development, 100 serial sections of the open biopsy specimen were made. Ten glomerular cysts were reconstructed using three-dimensional imaging analysis. Bowmans capsule (glomerular cyst) volume, the volume of glomerular tufts, and the area of the proximal tubular opening were estimated using imaging analysis. The volumes of Bowmans capsule and of glomerular tufts were 0.0098 +/- 0.0039 mm3 (mean +/- SD) (normal: 0.0041 to 0.0083 mm3) and 0.0026 +/- 0.0013 mm3, respectively. The area of the proximal tubular opening was 0.0017 +/- 0.0003 mm2 (normal: 0.0012 to 0.0028 mm2). There was neither obstruction nor stenosis of the opening of the renal tubule in this sporadic adult form of glomerulocystic kidney disease. After 4 years of hemodialysis, the glomerular cysts, as well as the kidneys, enlarged. This study shows that the main cause of glomerular cyst development is not glomerulotubular neck obstruction.

Persistent wedge-shaped contrast enhancement of the kidney

A case with a single wedge-shaped high-density area of the kidney that persists after urography was observed by CT scan. This might be an aberrant form of acute renal failure with multiple wedge-shaped contrast enhancement.

Changes of the hepatic CT absorption value in hemodialysis patients

The effect of hemodialysis on the CT absorption value of the liver was examined in 14 hemodialysis patients. In the high ultrafiltration group [10 patients with a weight loss of −1.7 to −3.5 (2.9 ± 0.6) kg], the hepatic CT absorption value increased from 49.6 ± 7.0 to 58.7 ± 8.7 Hounsfield units (p < 0.001) during hemodialysis. The increase in hepatic CT absorption value during dialysis correlated with the weight loss (p < 0.001, r = 0.798). A 5.3% body weight loss by ultrafiltration resulted in an 18.5% increase in the CT absorption value of the liver. This study suggests that one should be careful in making an early diagnosis of hepatic disease, especially hemosiderosis, in hemodialysis patients based on the hepatic CT absorption value because it is affected by hemodialysis.