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US, CT and MR Imaging Characteristics of Nephroblastomatosis
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commonly used modalities-sonography, scintigraphy, and magnetic resonance (MR) imaging. Acute scrotal disorders of children include acute epididymitis, torsion of an appendix testis or appendix epididymis, and torsion of the spermatic cord. Either scintigraphy or sonography may be used as the first imaging study, and both can aid in distinguishing among the disorders to different degrees. However, sonography is becoming the preferred modality, primarily because of the superior anatomic detail provided. Scrota1 masses are also best depicted with sonography, although MFi imaging can occasionally be a useful adjunctive modality. In cases of suspected cryptorchidism with equivocal clinical findings, both sonography and MR imaging may be useful, although sonography is usually the initial study. Knowledge of characteristic imaging appearances, as well as benefits and limitations of the available modalities, enables appropriate, expeditious radiologic evaluation of pediatric scrotal disorders.
Editorial Comment: On a monthly basis, RadioGmphics, which is published by the Radiological Society of North America, has excellent imaging review articles mostly culled from the scientific exhibits at their annual meeting. Usually anywhere from 1 to 4 articles are devoted to genitourinary topics and I strongly recommend them. The authors clearly review the multiple imaging modalities that are available for evaluation of the scrotum. They also review the entities that can be readily imaged and diagnosed as common scrotal abnormalities in the pediatric population. Acute scrotal disorders are reviewed including a pediatric case of a scrotal mass. Stanford M. Goldman, M.D.
Cystosonography With Echocontrast: A New Imaging Modality to Detect Vesicoureteric Reflux in Children M. BOSIO,Paediatric Department, Magenta Hospital and Advanced School of Paediatric Ultrasonography, Magenta, Italy Ped. Rad., 25: 250-255, 1998 Abstract Printed in J. Urol., 160 1592, 1998 Editorial Comment: The current gold standard for demonstrating significant reflux is the voiding cystourethrogram. However, this study exposes the child to radiation. Radionuclide cystography exposes the patient to less radiation and reveals significant reflux. However, it fails to show the anatomical abnormality that may underline the reflux, such as urethral valves in the male patient. The authors studied whether ultrasonic techniques using an echo contrast medium could be substituted for the current gold standard and, thus, obviate exposure to radiation. A total of 58 neonates were studied with a galactose suspension. These studies were compared to voiding cystourethrography and radionuclide cystography. It should be noted that not all patients had all 3 studies performed. The reasons for the evaluations included pyelectasis in 21 cases and pyelonephritis in 37. Echo sonography detected 76 refluxing units in 50 patients. Eight patients did not undergo voiding cystourethrography. In 43 patients voiding cystourethrography or radionuclide cystographydetected 62 refluxing units. Thus, the authors believe that echo sonography yields results comparable to voiding cystourethrography. If these excellent results are confirmed by others, one could seriously accept echo sonography as an adequate substitution for radionuclide cystography as the study of choice to following these cases. Although the authors claim that echo sonography did not fail to detect any anatomical variance, such as paraureteral diverticula, ureteroceles and duplication anomalies, I believe that posterior urethral valves can still be missed. Therefore, I would recommend that the initial study still be voiding cystourethrography. Stanford M. Goldman, M.D.
US,CT and MFt Imaging Characteristics of Nephroblastomatosis W. K. ROHRSCHNEIDER, A. WEIRICH, K. RIEDEN, K. DARGE, J. TROGER AND N. GRAF,Departments of Pediatric Radiology and Radiology, University of Heidelberg, Heidelberg, Heidelberg, and Department of Paediatric Oncology, Children’s Hospital, University of HomburglSaar, Hamburg, Germany Ped. Rad., 2 8 435-443, 1998 Objectives. To describe the imaging features of nephroblastomatosis with US, CT and MR, to point out characteristics of differentiation between nephrogenic rests (NR) and Wilms’ tumour (WT) and to determine the most appropriate imaging modality.
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Materials and methods. We reviewed the US, CT and MR images of 29 cases of histopathologically confirmed nephroblastomatosis sent to our department for reference evaluation (German nephroblastorna study). The series included 17 kidneys with NR, 6 kidneys with WT and 32 kidneys with both NR and WT. Results. NR presented as multinodular, peripheral, cortical lesions, the diffuse form of distribution being less common. Foci were homogeneous and of low echogenicity, density or signal intensity. The lesions were most clearly depicted with contrast-enhanced CT and T1-weighted (Tl-W)MR images. Lesions smaller than 1 cm were rarely identified by US. The most reliable criterion to differentiate NR from WT was their homogeneity. Conclusions. Contrast-enhanced CT and T1-W MR images are of similar potential and superior to US in the diagnosis of nephroblastomatosis. Due to the significant radiation dose of serial CT, MR imaging should be the method of choice wherever it is available. The cost-effectiveness and availability of US makes it ideal for serial follow-up of known lesions.
Editorial Comment: The authors review 29 cases of histopathologicallyproved nephroblastomatosis, including 17 kidneys with nephrogenic rests, 6 with Wilms tumor, and 32 with nephrogenic rests and Wilms tumor. They report that the multinodular peripheral form of nephrogenic rests was f a r more common than the diffuse form. Nephrogenic rests were homogeneous and of low echogenicity, density or signal intensity. Contrast enhanced computerized tomography and T1-weighted magnetic resonance imaging (MRI) more clearly depicted involvement of the kidney with nephrogenic rests than ultrasound. Lesions smaller than 1 cm. were often missed on ultrasound. The authors recommend that MRI be the method of choice because of the radiation exposure concern. However, the costmenefit factor must be included in choosing between these 2 studies at any institution. Ultrasound may be suitable for followup of patients with nephroblastomatosisfirst detected on computerized tomography or MRI. The major difficulty is differentiating Wilms tumor from nephrogenic rests. The problem is compounded by the fact that biopsy differentiation also can be extremely difficult from a microscopic point of view and because small lesions may be missed on biopsy. The authors suggest that the most reliable method to differentiate nephrogenic rests from Wilms tumor is that Wilms tumor tends to be inhomogeneous. However, in practice this differentiation is often difficult to make. Stanford M. Goldman, M.D.
Urinary Bladder Pseudolesions on Contrast-EnhancedHelical C T Frequency and Clinical Implications E. W. ~ L c o M. ~ , NINO-MURCIA AND J. S. RHEE,Departments of Radiology, Veterans AffairsPalo Alto Health Care System, Palo Alto and Stanford University School of Medicine, Stanford, California AJR, 171:1349-1354, 1998 OBJECTIVE. The goals of this study were to define the distinguishing characteristics and frequency of urinary bladder pseudolesions that are produced as opacified urine enters the bladder during contrastenhanced helical CT of the abdomen and to evaluate the usefulness of delayed imaging in differentiating pseudolesions from true lesions. SUBJECTS AND METHODS. Contrast-enhanced routine CT scans of 184 patients were obtained prospectively. For each patient, we also obtained 5-min delayed images of the bladder. The images were evaluated for apparent focal thickening or polypoid lesions involving the bladder wall, findings that may represent bladder neoplasia, without knowledge of the indications for the scan, the patient’s clinical history, or the patient’s diagnosis. Apparent lesions that were visible on routine images and entirely absent on delayed images were considered to be pseudolesions. RESULTS. Apparent lesions were identified on 20 (10.9% 2 4.5% [limits of the 95%confidence interval]) of the routine CT scans. Using delayed images, the 21 apparent lesions in these 20 patients were resolved as 13 pseudolesions and eight true lesions. Pseudolesions were present in 6.5% f 3.6% of patients. CONCLUSION. Pseudolesions of the bladder that are indistinguishable from true lesions pose a significant clinical problem in routine contrast-enhanced helical CT of the abdomen. Delayed imaging of the bladder is useful in distinguishing pseudolesions from true lesions.
Editorial Comment: The authors report 8 true and 13 pseudo lesions of the bladder among 184 patients who underwent contrast enhanced routine computerized tomography. The pseudo lesions were present in 6.5 f 3.6% of patients and represented apparent wall thickening as the result of mixing opacified and nonopacified urine in the bladder. These lesions appear as wall thickening or plypoid on computerized tomography, and are subsequently pmved by v-g imaging techniques not to represent any other pathological procesa True and pseudo lesions tend to be posterior, although they can be right or left anterior, and there is considerable overlap. It is important to recognize that wall thickening should not be readily dismissed as a pseudo lesion but rather must be confirmed as a true or pseudo lesion. Ipsilated hydronephro-
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commonly used modalities-sonography, scintigraphy, and magnetic resonance (MR) imaging. Acute scrotal disorders of children include acute epididymitis, torsion of an appendix testis or appendix epididymis, and torsion of the spermatic cord. Either scintigraphy or sonography may be used as the first imaging study, and both can aid in distinguishing among the disorders to different degrees. However, sonography is becoming the preferred modality, primarily because of the superior anatomic detail provided. Scrota1 masses are also best depicted with sonography, although MFi imaging can occasionally be a useful adjunctive modality. In cases of suspected cryptorchidism with equivocal clinical findings, both sonography and MR imaging may be useful, although sonography is usually the initial study. Knowledge of characteristic imaging appearances, as well as benefits and limitations of the available modalities, enables appropriate, expeditious radiologic evaluation of pediatric scrotal disorders.
Editorial Comment: On a monthly basis, RadioGmphics, which is published by the Radiological Society of North America, has excellent imaging review articles mostly culled from the scientific exhibits at their annual meeting. Usually anywhere from 1 to 4 articles are devoted to genitourinary topics and I strongly recommend them. The authors clearly review the multiple imaging modalities that are available for evaluation of the scrotum. They also review the entities that can be readily imaged and diagnosed as common scrotal abnormalities in the pediatric population. Acute scrotal disorders are reviewed including a pediatric case of a scrotal mass. Stanford M. Goldman, M.D.
Cystosonography With Echocontrast: A New Imaging Modality to Detect Vesicoureteric Reflux in Children M. BOSIO,Paediatric Department, Magenta Hospital and Advanced School of Paediatric Ultrasonography, Magenta, Italy Ped. Rad., 25: 250-255, 1998 Abstract Printed in J. Urol., 160 1592, 1998 Editorial Comment: The current gold standard for demonstrating significant reflux is the voiding cystourethrogram. However, this study exposes the child to radiation. Radionuclide cystography exposes the patient to less radiation and reveals significant reflux. However, it fails to show the anatomical abnormality that may underline the reflux, such as urethral valves in the male patient. The authors studied whether ultrasonic techniques using an echo contrast medium could be substituted for the current gold standard and, thus, obviate exposure to radiation. A total of 58 neonates were studied with a galactose suspension. These studies were compared to voiding cystourethrography and radionuclide cystography. It should be noted that not all patients had all 3 studies performed. The reasons for the evaluations included pyelectasis in 21 cases and pyelonephritis in 37. Echo sonography detected 76 refluxing units in 50 patients. Eight patients did not undergo voiding cystourethrography. In 43 patients voiding cystourethrography or radionuclide cystographydetected 62 refluxing units. Thus, the authors believe that echo sonography yields results comparable to voiding cystourethrography. If these excellent results are confirmed by others, one could seriously accept echo sonography as an adequate substitution for radionuclide cystography as the study of choice to following these cases. Although the authors claim that echo sonography did not fail to detect any anatomical variance, such as paraureteral diverticula, ureteroceles and duplication anomalies, I believe that posterior urethral valves can still be missed. Therefore, I would recommend that the initial study still be voiding cystourethrography. Stanford M. Goldman, M.D.
US,CT and MFt Imaging Characteristics of Nephroblastomatosis W. K. ROHRSCHNEIDER, A. WEIRICH, K. RIEDEN, K. DARGE, J. TROGER AND N. GRAF,Departments of Pediatric Radiology and Radiology, University of Heidelberg, Heidelberg, Heidelberg, and Department of Paediatric Oncology, Children’s Hospital, University of HomburglSaar, Hamburg, Germany Ped. Rad., 2 8 435-443, 1998 Objectives. To describe the imaging features of nephroblastomatosis with US, CT and MR, to point out characteristics of differentiation between nephrogenic rests (NR) and Wilms’ tumour (WT) and to determine the most appropriate imaging modality.
IMAGING
Materials and methods. We reviewed the US, CT and MR images of 29 cases of histopathologically confirmed nephroblastomatosis sent to our department for reference evaluation (German nephroblastorna study). The series included 17 kidneys with NR, 6 kidneys with WT and 32 kidneys with both NR and WT. Results. NR presented as multinodular, peripheral, cortical lesions, the diffuse form of distribution being less common. Foci were homogeneous and of low echogenicity, density or signal intensity. The lesions were most clearly depicted with contrast-enhanced CT and T1-weighted (Tl-W)MR images. Lesions smaller than 1 cm were rarely identified by US. The most reliable criterion to differentiate NR from WT was their homogeneity. Conclusions. Contrast-enhanced CT and T1-W MR images are of similar potential and superior to US in the diagnosis of nephroblastomatosis. Due to the significant radiation dose of serial CT, MR imaging should be the method of choice wherever it is available. The cost-effectiveness and availability of US makes it ideal for serial follow-up of known lesions.
Editorial Comment: The authors review 29 cases of histopathologicallyproved nephroblastomatosis, including 17 kidneys with nephrogenic rests, 6 with Wilms tumor, and 32 with nephrogenic rests and Wilms tumor. They report that the multinodular peripheral form of nephrogenic rests was f a r more common than the diffuse form. Nephrogenic rests were homogeneous and of low echogenicity, density or signal intensity. Contrast enhanced computerized tomography and T1-weighted magnetic resonance imaging (MRI) more clearly depicted involvement of the kidney with nephrogenic rests than ultrasound. Lesions smaller than 1 cm. were often missed on ultrasound. The authors recommend that MRI be the method of choice because of the radiation exposure concern. However, the costmenefit factor must be included in choosing between these 2 studies at any institution. Ultrasound may be suitable for followup of patients with nephroblastomatosisfirst detected on computerized tomography or MRI. The major difficulty is differentiating Wilms tumor from nephrogenic rests. The problem is compounded by the fact that biopsy differentiation also can be extremely difficult from a microscopic point of view and because small lesions may be missed on biopsy. The authors suggest that the most reliable method to differentiate nephrogenic rests from Wilms tumor is that Wilms tumor tends to be inhomogeneous. However, in practice this differentiation is often difficult to make. Stanford M. Goldman, M.D.
Urinary Bladder Pseudolesions on Contrast-EnhancedHelical C T Frequency and Clinical Implications E. W. ~ L c o M. ~ , NINO-MURCIA AND J. S. RHEE,Departments of Radiology, Veterans AffairsPalo Alto Health Care System, Palo Alto and Stanford University School of Medicine, Stanford, California AJR, 171:1349-1354, 1998 OBJECTIVE. The goals of this study were to define the distinguishing characteristics and frequency of urinary bladder pseudolesions that are produced as opacified urine enters the bladder during contrastenhanced helical CT of the abdomen and to evaluate the usefulness of delayed imaging in differentiating pseudolesions from true lesions. SUBJECTS AND METHODS. Contrast-enhanced routine CT scans of 184 patients were obtained prospectively. For each patient, we also obtained 5-min delayed images of the bladder. The images were evaluated for apparent focal thickening or polypoid lesions involving the bladder wall, findings that may represent bladder neoplasia, without knowledge of the indications for the scan, the patient’s clinical history, or the patient’s diagnosis. Apparent lesions that were visible on routine images and entirely absent on delayed images were considered to be pseudolesions. RESULTS. Apparent lesions were identified on 20 (10.9% 2 4.5% [limits of the 95%confidence interval]) of the routine CT scans. Using delayed images, the 21 apparent lesions in these 20 patients were resolved as 13 pseudolesions and eight true lesions. Pseudolesions were present in 6.5% f 3.6% of patients. CONCLUSION. Pseudolesions of the bladder that are indistinguishable from true lesions pose a significant clinical problem in routine contrast-enhanced helical CT of the abdomen. Delayed imaging of the bladder is useful in distinguishing pseudolesions from true lesions.
Editorial Comment: The authors report 8 true and 13 pseudo lesions of the bladder among 184 patients who underwent contrast enhanced routine computerized tomography. The pseudo lesions were present in 6.5 f 3.6% of patients and represented apparent wall thickening as the result of mixing opacified and nonopacified urine in the bladder. These lesions appear as wall thickening or plypoid on computerized tomography, and are subsequently pmved by v-g imaging techniques not to represent any other pathological procesa True and pseudo lesions tend to be posterior, although they can be right or left anterior, and there is considerable overlap. It is important to recognize that wall thickening should not be readily dismissed as a pseudo lesion but rather must be confirmed as a true or pseudo lesion. Ipsilated hydronephro-
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