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Applications of Spiral CT in Genitourinary Imaging
362
IMAGING
The authors suggest setting a compromise position of a threshold, such as 10 HU. By doing SO their patients could be assured that they did not have malignancy and did not need followup. I have a major objection to the approach of the authors. The unenhanced study is not the only available methodology of separating adenoma from malignancy. One could enhance the lesion as was suggested in the aforementioned article by Szolar and Kammerhuber. One could also use magnetic resonance imaging techniques. I also do not object to telling the patient that the lesion is most likely benign and then following up at periodic intervals. Thus, in many cases one can set Hounsfield units higher than 10 HU as a threshold and in appropriate situations follow the patients to see if there is any change. Stanford M. Goldman, M.D. Applications of Spiral CT in Genitourinary Imaging S. T. COCHRAN, Department ofRadiologica1 Sciences, UCLA Medical Center for Health Sciences, Los Angeles, California Acad. Rad., 5 380-389, 1998 Spiral computed tomography (CT), which is also called helical or volume-acquisition CT, is performed by advancing the patient on the gantry during simultaneous tube rotation with continuous x-ray exposure. This represents the latest technologic advance in CT imaging (1).The 1-second tube rotations coupled with continuous forward movement of the table permits volumetric acquisition of patient data during a single breath hold. tk2Spiral CT has advantages over conventional, incremental CT for imaging of the genitourinary tract. In the evaluation of the renal parenchyma for masses and stones, the elimination of respiratory misregistration and the ability to reconstruct overlapping images at arbitrary intervals improves visualization. In patients with symptoms of acute urinary tract obstruction, short acquisition times allow us to replace excretory urography with unenhanced spiral CT of the abdomen and pelvis for evaluation. Contrast material enhancement can be optimized by appropriate timing of the spiral scanning to coincide with peak contrast enhancement, thus enabling new applications such as CT angiography (2). This article describes and discusses the new imaging applications that are now possible with spiral CT technology. Editorial Comment: This article is 1 in a series of articles in the "New Developments in Medicine" section of Academic Radiology. It is an excellent review of the current status of applications of spiral CT,and I recommend it for those who are interested in a brief review of this subject. Stanford M. Goldman, M.D. Childhood F'yelonephritis: Comparison of Gadolinium-EnhancedMR Imaging and Renal Cortical Scintigraphy for Diagnosis
G. J. LONERGAN, D. J. PENNINGTON, J. C. MORRISON, R. M. Haws, M. S. GRIMLEY AND T.-C. GO, Departments of Diagnostic Radiology, Nuclear Medicine and Pediatrics, Wilford Hall Medical Center, Lackland Air Force Base, Sun Antonio, Texas, Departments of Radiology and Nuclear Medicine, and Preventive Medicine, Uniformed Services University of Health Sciences, Bethesda, Maryland, and Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, D. C. Radiology, 207: 377-384, 1998 PURPOSE: To compare gadolinium-enhanced inversion-recovery magnetic resonance (MR) imaging with renal cortical scintigraphy in the diagnosis of childhood pyelonephritis. MATERIALS AND METHODS: Thirty-seven patients with fever-producing urinary tract infection underwent gadolinium-enhanced inversion-recovery MR imaging and technetium-99m renal cortical scintigraphy. Each study was read in double-blind fashion by two radiologists. The kidney was divided into three zones, and each was graded as positive, equivocal, or negative for pyelonephritis. RESULTS: Seventy kidneys (210 zones) were imaged. Twenty-six kidneys (54 zones) had evidence of pyelonephritis at both MR imaging and scintigraphy. Twenty-four kidneys (100 zones) were negative on both studies. Twelve kidneys (42 zones) were positive at MR imaging but negative at scintigraphy, and four kidneys (seven zones) were negative a t MR imaging but positive a t scintigraphy. The results of MR imaging for pyelonephritis were not equivalent to the results of scintigraphy (P = .001 for renal zones). The proportion of positive agreement between readers for the presence of pyelonephritis was 0.85 and 0.57 for MR imaging and scintigraphy, respectively. The proportion of negative agreement was 0.88 and 0.80 for MR imaging and scintigraphy, respectively. CONCLUSION: Gadolinium-enhanced inversion-recovery MR imaging enabled detection of more pyelonephritic lesions than did renal cortical scintigraphy and had superior interobserver agreement.
Editorial Comment: For some the gold standard for the diagnosis of pyelonephritis using imaging techniques has been renal scintigraphy, which has been claimed to be the most sensitive and has a definite correlation for prognosticating outcome. Pediatric radiologists, pediatricians and pediatric urologists have promoted this technique because there is little exposure
IMAGING
The authors suggest setting a compromise position of a threshold, such as 10 HU. By doing SO their patients could be assured that they did not have malignancy and did not need followup. I have a major objection to the approach of the authors. The unenhanced study is not the only available methodology of separating adenoma from malignancy. One could enhance the lesion as was suggested in the aforementioned article by Szolar and Kammerhuber. One could also use magnetic resonance imaging techniques. I also do not object to telling the patient that the lesion is most likely benign and then following up at periodic intervals. Thus, in many cases one can set Hounsfield units higher than 10 HU as a threshold and in appropriate situations follow the patients to see if there is any change. Stanford M. Goldman, M.D. Applications of Spiral CT in Genitourinary Imaging S. T. COCHRAN, Department ofRadiologica1 Sciences, UCLA Medical Center for Health Sciences, Los Angeles, California Acad. Rad., 5 380-389, 1998 Spiral computed tomography (CT), which is also called helical or volume-acquisition CT, is performed by advancing the patient on the gantry during simultaneous tube rotation with continuous x-ray exposure. This represents the latest technologic advance in CT imaging (1).The 1-second tube rotations coupled with continuous forward movement of the table permits volumetric acquisition of patient data during a single breath hold. tk2Spiral CT has advantages over conventional, incremental CT for imaging of the genitourinary tract. In the evaluation of the renal parenchyma for masses and stones, the elimination of respiratory misregistration and the ability to reconstruct overlapping images at arbitrary intervals improves visualization. In patients with symptoms of acute urinary tract obstruction, short acquisition times allow us to replace excretory urography with unenhanced spiral CT of the abdomen and pelvis for evaluation. Contrast material enhancement can be optimized by appropriate timing of the spiral scanning to coincide with peak contrast enhancement, thus enabling new applications such as CT angiography (2). This article describes and discusses the new imaging applications that are now possible with spiral CT technology. Editorial Comment: This article is 1 in a series of articles in the "New Developments in Medicine" section of Academic Radiology. It is an excellent review of the current status of applications of spiral CT,and I recommend it for those who are interested in a brief review of this subject. Stanford M. Goldman, M.D. Childhood F'yelonephritis: Comparison of Gadolinium-EnhancedMR Imaging and Renal Cortical Scintigraphy for Diagnosis
G. J. LONERGAN, D. J. PENNINGTON, J. C. MORRISON, R. M. Haws, M. S. GRIMLEY AND T.-C. GO, Departments of Diagnostic Radiology, Nuclear Medicine and Pediatrics, Wilford Hall Medical Center, Lackland Air Force Base, Sun Antonio, Texas, Departments of Radiology and Nuclear Medicine, and Preventive Medicine, Uniformed Services University of Health Sciences, Bethesda, Maryland, and Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, D. C. Radiology, 207: 377-384, 1998 PURPOSE: To compare gadolinium-enhanced inversion-recovery magnetic resonance (MR) imaging with renal cortical scintigraphy in the diagnosis of childhood pyelonephritis. MATERIALS AND METHODS: Thirty-seven patients with fever-producing urinary tract infection underwent gadolinium-enhanced inversion-recovery MR imaging and technetium-99m renal cortical scintigraphy. Each study was read in double-blind fashion by two radiologists. The kidney was divided into three zones, and each was graded as positive, equivocal, or negative for pyelonephritis. RESULTS: Seventy kidneys (210 zones) were imaged. Twenty-six kidneys (54 zones) had evidence of pyelonephritis at both MR imaging and scintigraphy. Twenty-four kidneys (100 zones) were negative on both studies. Twelve kidneys (42 zones) were positive at MR imaging but negative at scintigraphy, and four kidneys (seven zones) were negative a t MR imaging but positive a t scintigraphy. The results of MR imaging for pyelonephritis were not equivalent to the results of scintigraphy (P = .001 for renal zones). The proportion of positive agreement between readers for the presence of pyelonephritis was 0.85 and 0.57 for MR imaging and scintigraphy, respectively. The proportion of negative agreement was 0.88 and 0.80 for MR imaging and scintigraphy, respectively. CONCLUSION: Gadolinium-enhanced inversion-recovery MR imaging enabled detection of more pyelonephritic lesions than did renal cortical scintigraphy and had superior interobserver agreement.
Editorial Comment: For some the gold standard for the diagnosis of pyelonephritis using imaging techniques has been renal scintigraphy, which has been claimed to be the most sensitive and has a definite correlation for prognosticating outcome. Pediatric radiologists, pediatricians and pediatric urologists have promoted this technique because there is little exposure