Computerized tomography was performed on 19 patients diagnosed as having uncomplicated acute pyelonephritis. The relationship was investigated among the laboratory findings, presence of flank pain, clinical course and severity of the lesions detected by computerized tomography. In patients febrile for less than 2 weeks healing as assessed by computerized tomography took an average of 76 days. However, in patients with repeated febrile episodes occurring for longer than 2 weeks healing was delayed until an average 232 days after onset. Computerized tomography findings generally correlated well with the erythrocyte sedimentation rate, C-reactive protein level, and presence of pyuria and flank pain. However, in patients with a prolonged course computerized tomography proved to be a more reliable indicator of progress than either the results of laboratory tests or the symptoms. In conclusion, computerized tomography was useful in the diagnosis, assessment of severity and evaluation of healing of acute pyelonephritis.

A series of 14 patients with acute pyelonephritis was evaluated for the formation of renal scarring by serial computed tomography (CT) and intravenous urography. Although the urography results were normal, CT showed renal parenchymal atrophy (cortical scarring) in 6 patients. Cortical scarring was observed to occur after 61 to 187 days, and it was slower to develop in the patients with recurrent fever lasting for 2 weeks or more in total than in those with fever for less than 2 weeks. Scarring was significantly more frequent in patients with severe renal involvement than in those with mild involvement, and scars developed at the sites of the most extensive lesions seen on the initial CT scans. Cortical scars were detected in 6 of the 7 patients in whom the lesions occupied 30% or more of the renal parenchyma. We conclude that the extent of the initial renal parenchymal involvement was the most important determinant of eventual scar formation.

Twenty-nine kidneys of seventeen patients (nine boys and eight girls) with vesicoureteral reflux and repeated urinary tract infection were studied by magnetic resonance imaging for diagnosis of renal scarring and correlation between clinical data and the degree renal scarring. Renal scarring is classified into three types according to findings in magnetic resonance imaging. The degree of renal scarring are classified into five grades according to traditional grading of intravenous pyelogram. If a fine deformity of calyx is shown on intravenous pyelogram, magnetic resonance imaging demonstrates renal scarring. Magnetic resonance imaging without irradiation is exceedingly valuable for the diagnosis of renal scarring. The appearances of magnetic resonance imaging were supported by X-ray computed tomography. There is a substantial correlation between serum creatinine and the grades of renal scarring by magnetic resonance imaging. There is a substantial correlation between fever attacks and the grade of renal scarring, and there is a significant reverse correlation between the age of the onset of upper urinary tract infection and the grade of renal scarring. It is suggested that upper urinary tract infection is the most significant factor in scar formation.