PET-CT in presurgical lymph node staging in non-small cell lung cancer: the importance of false-negative and false-positive findings. / La PET-TC en la estadificación ganglionar prequirúrgica del carcinoma de pulmón de células no pequeñas: implicación de los falsos negativos y falsos positivos.

OBJECTIVE: To assess the importance of false-negative and false-positive findings in computed tomography (CT) and 18F-FDG positron emission tomography (PET) in mediastinal lymph node staging in patients undergoing surgery for non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: This retrospective study included 113 consecutive patients and 120 resected NSCLCs; 22 patients received neoadjuvant treatment. We compared the findings on preoperative 18F-FDG PET-CT studies with the postoperative pathology findings. Lymph node size and primary tumor size were measured with CT, and lymph nodes and primary tumors were evaluated qualitatively and semiquantitatively (using standardized uptake values (SUVmax)) with PET. RESULTS: Metastatic lymph nodes were found in 26 (21.7%) of the 120 tumors and in 41 (7.7%) of the 528 lymph node stations analyzed. 18F-FDG PET-CT yielded 53.8% sensitivity, 76.6% specificity, 38.9% positive predictive value, 85.7% negative predictive value, and 71.7% diagnostic accuracy. The false-negative rate was 14.2%. Multivariable analysis found that the factors associated with false-negative findings were a moderate degree of differentiation in the primary tumor (p = 0.005) and an SUVmax of the primary tumor >4 (p = 0.027). The false-positive rate was 61.1%, and the multivariable analysis found that lymph node size >1cm was associated with false-positive findings (p < 0.001). CONCLUSIONS: In mediastinal lymph node staging in patients with NSCLC, 18F-FDG PET-CT improves the specificity and negative predictive value and helps clinicians to select the patients that will benefit from surgery. Given the high rate of false positives, histological confirmation of positive cases is recommendable.

Breslow thickness and (18)F-FDG PET-CT result in initial staging of cutaneous melanoma: Can a cut-off point be established?

AIM: To establish a Breslow Thickness (BT) cut-off point for indication of PET-CT of cutaneous melanoma in early stages and evaluate its prognostic value. MATERIAL AND METHODS: Retrospective analysis of 347 PET-CT studies with diagnosis of melanoma, of which 108 were performed for initial staging. Thirty-one patients were excluded, and a final sample of 77 patients remained. A ROC curve analysis was performed to establish an optimal cut-off point. A survival analysis was performed, considering death assignable to melanoma as the main event, for the evaluation of its prognostic value. RESULTS: Forty-seven (61.04%) of all 77 patients selected were men, and 11 (14.29%) had a positive PET-CT result. Mean age was 65.17±15.00 years. The median BT in patients with a negative PET-CT result was 2.75 mm (IQR 1.83-4.50) and in the positive group 6.25 mm (IQR 5.40-7.50) (P=.0013). In the ROC curve analysis (AUC 0.804, SE 0.054), an optimal value of 5 mm BT with the following values was obtained: sensitivity 90.91%, specificity 78.79%, negative predictive value (NPV) 98.1%, positive predictive value (PPV) 41.7%, diagnostic OR 37.1, and accuracy 80.52%. Mean follow-up was 18.66±14,35 months, detecting 2/53 (3.77%) deaths in the BT<5 mm group, and 7/24 (29.17%) in the BT≥5 mm group. Survival curves between both groups were significantly different (P=.0013). CONCLUSIONS: A 5 mm cut-off point correctly distinguishes those patients with positive PET-CT from those with negative results in the early stages of cutaneous melanoma; therefore it could be included in initial staging of this subgroup of patients.

Prognostic value of metabolic tumour volume and total lesion glycolysis in 18F-FDG PET/CT scans in locally advanced breast cancer staging. / Papel pronóstico del volumen metabólico tumoral y de la glucólisis tumoral total en los estudios 18F-FDG PET/TC de estadificación del cáncer localmente avanzado de mama.

OBJECTIVE: To determine whether metabolic tumour volume (MTV) and total lesion glycolysis (TLG) are able to predict recurrence risk in locally advanced breast cancer (LABC) patients. MATERIAL AND METHODS: Retrospective study of LABC patients who undertook neoadjuvant, local and adjuvant treatment and follow up. A 18F-FDG PET/CT study for initial staging was performed analysing in this study different metabolic parameters (MTV, TLG, SUVmax and SUVmed) both in the primary tumour (T) as well as in axillary nodes (N) and whole-body (WB). RESULTS: Forty females were included between January 2010-2011; follow up until January 2015 was completed. The average follow-up was 46 months. Twenty percent presented recurrence: local disease (n=2) and distant metastasis (n=6); 3 patients died (38% of the patients which recurred and 7.5% from the total). SUVmax, MTV and TLG, in T, N and WB, were higher in those patients with recurrence. The MTV and TLG parameters in the tumour (T) were related to the recurrence rate (P=.020 and P=.028, respectively); whereas SUVmax in the lymph nodes (N) was significantly related (P=.008) to the recurrence rate. The best cut-off points to predict recurrence where: MTV T ≥19.3cm3, TLG T≥74.4g and SUVmax N≥13.8, being 10-12 times more likely to recidivate when these thresholds where exceeded. Tumour grade was the only clinical-pathological variable which was related to recurrence probability (p=.035). CONCLUSIONS: In this study of LABC patients the metabolic parameters which have a better relationship with recurrence rate are: MTV and TLG in the primary tumour, SUVmax in the regional lymph node disease and whole-body PET data.

18F-FDG PET-CT imaging in the neoadjuvant setting for stages II-III breast cancer: association of loco­regional SUVmax with classical prognostic factors.

AIM: Classical prognostic and predictive factors serve to predict outcome and response to neoadjuvant treatment in stage II and III breast cancer. The purpose is to determine the relation between the SUVmax of the locoregional disease with these classical prognostic factors. METHODS: A prospective study including 43 stage II and III breast cancer patients was performed. In all the patients, two 18F-FDG PET-CT studies were performed before and after neoadjuvant chemotherapy. After this treatment, surgery and adjuvant treatment were carried out. To combine the information of the locoregional disease, the SUVmax of the lesion (tumor or abnormal lymphnodes) with the highest uptake was used. SUVmax and prognostic factors were studied with the Kruskal-Wallis non-parametric test and with the Mann-Whitney U. RESULTS: A statistically significant association between elevated SUVmax value and absence of estrogen receptors (ER) expression (16 vs.. 10; P<0.019) was found. Locorregional disease with positive HER2 phenotype had a statistically significant SUVmax value greater than Luminal A (estrogen and/or progesterone positive receptors with Ki67<15%) and B (estrogen and/or progesterone positive receptors with Ki67≥to 15%) (13.4 vs. 7.9 and 8.9; P<0.022 and P<0.024, respectively). Triple negative phenotype disease had higher SUVmax than Luminal A and B (15.4; P<0.030 and P<0.038). Positive correlation between the percentage of the Ki67 Proliferation Index and SUVmax (P<0.007) was demonstrated. High grade disease had a higher SUVmax than low grade (P<0.004). CONCLUSION: Locorregional SUVmax is associated to prognostic and predictive factors and reaffirms the utility of PET-CT as a tool in the common clinical practice.

[The impact on diagnostic quality of using contrast media in PET-CT studies]. / Calidad diagnóstica y repercusión del empleo de contrastes en los estudios de tomografía computarizada de exploraciones con tomografía por emisión de positrones en combinación con tomografía computarizada.

OBJECTIVE: To evaluate the impact of using radiologic contrast media on the quality of PET-CT studies at our center. MATERIAL AND METHODS: This is a retrospective observational study to evaluate the quality of the PET-CT studies carried out with radiologic contrast media and the presence of artifacts due to these contrast agents. Oncologic patients in whom PET was indicated according to the manufacturer's specifications for FDG ((18)F-2-fluoro-2-deoxy-D-glucose) underwent PET-CT study on a PET-CT system with a six-detector-row CT scanner. RESULTS: Between February 2009 and June 2009, we performed 612 PET-CT examinations in 369 male patients and 243 female patients. Iodinated contrast media were administered intravenously in 48% and orally in 18%. Diagnostic quality was considered high in 93.5% of the studies, intermediate in 4.3%, and low in 2.2%. In the CT studies performed using intravenous contrast agents, artifacts were identified in 8% and resulted in diagnostic uncertainty in the PET study in 1.4%. We found no diagnostic problems caused by oral contrast agents in any case. CONCLUSIONS: The use of radiologic contrast agents in PET-CT studies does not negatively affect diagnostic quality or workflow. Given that we can improve the ability of PET-CT to detect lesions by enhancing the diagnostic quality of the CT study, we consider it appropriate to include the administration of contrast agents in protocols for PET-CT studies.

[Nephroblastomatosis vs Wilms' tumor: a case report]. / Nefroblastomatosis frente a tumor de Wilms: a propósito de un caso.

Nephroblastomatosis is an abnormality of nephrogenesis and has been defined as the persistence of metanephric blastema into infancy. The association of these foci of fetal tissue with Wilms' tumor has been repeatedly documented in the literature. Numerous imaging modalities currently enable the detection of nephroblastomatosis and follow-up of patients to detect neoplastic change, which is especially indicated during infancy and early childhood, when the likelihood of Wilms' tumor developing is highest.

La PET-TC en la estadificación ganglionar prequirúrgica del carcinoma de pulmón de células no pequeñas: implicación de los falsos negativos y falsos positivos / PET-CT in presurgical lymph node staging in non-small cell lung cancer: the importance of false-negative and false-positive findings

Objetivo. Valorar las implicaciones de los falsos negativos (FN) y de los falsos positivos (FP) de la tomografía computarizada (TC) y la tomografía por emisión de positrones (PET) con fluorodesoxiglucosa (18F-FDG) en nuestro medio en la estadificación ganglionar mediastínica de pacientes operados de carcinoma de pulmón de células no pequeñas (CPCNP). Material y métodos. Estudio retrospectivo de 113 pacientes consecutivos con 120 CPCNP operados; 22 pacientes recibieron tratamiento neoadyuvante. Se compararon los resultados obtenidos en la 18F-FDG PET-TC prequirúrgica con los patológicos. Se analizaron el tamaño ganglionar y del tumor primario en la TC, y su valoración cualitativa y semicuantitativa (SUVmáx) en la PET. Resultados. Se encontraron ganglios metastásicos en el 21,7% de los 120 tumores y en el 7,7% de las 528 estaciones ganglionares analizadas. La 18F-FDG PET-TC en el estudio por tumor mostró una sensibilidad del 53,8%, una especificidad del 76,6%, un valor predictivo positivo del 38,9%, un valor predictivo negativo del 85,7% y una precisión diagnóstica del 71,7%. La tasa de FN fue del 14,2%. El análisis multivariable mostró que un grado de diferenciación moderado del tumor primario (p = 0,005) y una SUVmáx del tumor primario >4 (p = 0,027) eran los factores asociados con los FN. La tasa de FP fue del 61,1% y el tamaño ganglionar >1cm era el factor asociado con los FP (p <0,001). Conclusiones. La 18F-FDG PET-TC en la estadificación ganglionar mediastínica de pacientes con CPCNP mejora la especificidad y el valor predictivo negativo, y ayuda al clínico a seleccionar los pacientes que se beneficiarán de la cirugía. Dada la elevada tasa de FP, es recomendable que, antes de excluir a pacientes de la cirugía, se confirmen histológicamente los casos positivos (AU)

Objective. To assess the importance of false-negative and false-positive findings in computed tomography (CT) and 18F-FDG positron emission tomography (PET) in mediastinal lymph node staging in patients undergoing surgery for non-small cell lung cancer (NSCLC). Material and methods. This retrospective study included 113 consecutive patients and 120 resected NSCLCs; 22 patients received neoadjuvant treatment. We compared the findings on preoperative 18F-FDG PET-CT studies with the postoperative pathology findings. Lymph node size and primary tumor size were measured with CT, and lymph nodes and primary tumors were evaluated qualitatively and semiquantitatively (using standardized uptake values (SUVmax)) with PET. Results. Metastatic lymph nodes were found in 26 (21.7%) of the 120 tumors and in 41 (7.7%) of the 528 lymph node stations analyzed. 18F-FDG PET-CT yielded 53.8% sensitivity, 76.6% specificity, 38.9% positive predictive value, 85.7% negative predictive value, and 71.7% diagnostic accuracy. The false-negative rate was 14.2%. Multivariable analysis found that the factors associated with false-negative findings were a moderate degree of differentiation in the primary tumor (p = 0.005) and an SUVmax of the primary tumor >4 (p = 0.027). The false-positive rate was 61.1%, and the multivariable analysis found that lymph node size >1cm was associated with false-positive findings (p < 0.001). Conclusions. In mediastinal lymph node staging in patients with NSCLC, 18F-FDG PET-CT improves the specificity and negative predictive value and helps clinicians to select the patients that will benefit from surgery. Given the high rate of false positives, histological confirmation of positive cases is recommendable (AU)

Co-existence of a giant cell tumour of the tendon sheath and schwannoma in a patient with bilateral breast cancer: A potential cause of false positive findings in 18F-FDG PET/CT studies / Coexistencia de tumor de células gigantes de la vaina tendinosa y de schwannoma en paciente con cáncer de mama bilateral: causa potencial de falsos positivos en estudios 18F-FDG PET/TC

No disponible

Adenomatosis hepática múltiple con captación de 18F-FDG: una manifestación rara de una entidad poco frecuente / Multiple liver adenomatosis with 18F-FDG uptake: a rare manifestation of an infrequent entity

No disponible

Papel pronóstico del volumen metabólico tumoral y de la glucólisis tumoral total en los estudios 18F-FDG PET/TC de estadificación del cáncer localmente avanzado de mama / Prognostic value of metabolic tumour volume and total lesion glycolysis in 18F-FDG PET/CT scans in locally advanced breast cancer staging

Objetivo. Conocer si el volumen metabólico tumoral (VMT) y la glucólisis tumoral total (GTT) pueden predecir el riesgo de recurrencia en cáncer localmente avanzado de mama (CLAM). Material y métodos. Estudio retrospectivo de pacientes con CLAM tratados con tratamiento neoadyuvante, local y adyuvante; en seguimiento. Se realizó una 18F-FDG PET/TC para estadificar la enfermedad, midiéndose diferentes parámetros metabólicos (VMT, GTT, SUVmáx y SUVmed), tanto en el tumor primario (T) como en los ganglios metastásicos (N) y en el cuerpo entero (CE). Resultados. Se incluyeron 40 mujeres entre enero de 2010-2011; seguimiento hasta enero de 2015. Con una mediana de seguimiento de 46 meses el 20% tuvieron recidiva, local (n=2) o a distancia (n=6); fallecieron 3 (38% de aquellas con recidiva y 7,5% del total). EL SUVmáx, VMT y GTT, tanto en T, como N y CE, fue mayor en aquellas que presentaron recidiva. En el T tanto el VMT como la GTT se relacionaron con la recidiva de la enfermedad (p=0,020 y p=0,028, respectivamente), mientras que en la N fue el SUVmáx (p=0,008). Los puntos de corte óptimos para predecir recurrencia fueron: VMT T≥19,3cm3, GTT T≥74,4g y SUVmáx N≥13,8, existiendo 10-12 veces más probabilidad de experimentar progresión tumoral cuando superaban estos umbrales. El grado tumoral fue la única variable clínico-patológica asociada con la recidiva (p=0,035). Conclusiones. En este estudio de CLAM los parámetros metabólicos que más se asocian con la tasa de recidiva son el VMT y la GTT en el tumor primario, el SUVmáx en la enfermedad ganglionar regional y los 3 índices PET en el cuerpo entero. Estos parámetros podrían utilizarse en la práctica asistencial para identificar a las pacientes con mayor riesgo (AU)

Objective. To determine whether metabolic tumour volume (MTV) and total lesion glycolysis (TLG) are able to predict recurrence risk in locally advanced breast cancer (LABC) patients. Material and methods. Retrospective study of LABC patients who undertook neoadjuvant, local and adjuvant treatment and follow up. A 18F-FDG PET/CT study for initial staging was performed analysing in this study different metabolic parameters (MTV, TLG, SUVmax and SUVmed) both in the primary tumour (T) as well as in axillary nodes (N) and whole-body (WB). Results. Forty females were included between January 2010-2011; follow up until January 2015 was completed. The average follow-up was 46 months. Twenty percent presented recurrence: local disease (n=2) and distant metastasis (n=6); 3 patients died (38% of the patients which recurred and 7.5% from the total). SUVmax, MTV and TLG, in T, N and WB, were higher in those patients with recurrence. The MTV and TLG parameters in the tumour (T) were related to the recurrence rate (P=.020 and P=.028, respectively); whereas SUVmax in the lymph nodes (N) was significantly related (P=.008) to the recurrence rate. The best cut-off points to predict recurrence where: MTV T ≥19.3cm3, TLG T≥74.4g and SUVmax N≥13.8, being 10-12 times more likely to recidivate when these thresholds where exceeded. Tumour grade was the only clinical-pathological variable which was related to recurrence probability (p=.035). Conclusions. In this study of LABC patients the metabolic parameters which have a better relationship with recurrence rate are: MTV and TLG in the primary tumour, SUVmax in the regional lymph node disease and whole-body PET data (AU)

Relación entre el índice de Breslow y el resultado de la PET-TC en la estadificación inicial del melanoma cutáneo: ¿es posible establecer un punto de corte? / Breslow thickness and 18F-FDG PET-CT result in initial staging of cutaneous melanoma: Can a cut-off point be established?

Objetivo. Establecer un punto de corte del índice de Breslow (IB) para la indicación del estudio PET-TC en la estadificación del melanoma cutáneo en estadios iniciales y evaluar su valor pronóstico. Material y métodos. Análisis retrospectivo de 347 estudios PET-TC con 18F-FDG con diagnóstico de melanoma, siendo 108 de estadificación. Excluimos 31 obteniendo una muestra final de 77 pacientes. Para establecer el punto de corte óptimo llevamos a cabo un análisis de la curva ROC. Para evaluar el valor pronóstico se realizó un análisis de supervivencia registrando la muerte atribuible al melanoma. Resultados. De los 77 pacientes, 47 eran varones (61,04%) y 11 (14,29%) presentaron un resultado PET-TC positivo. La edad media fue 65,17 ± 15,00 años. La mediana del IB en el grupo con PET-TC negativo fue 2,75 mm (IQR 1,83-4,50) y en el grupo con resultado positivo 6,25 mm (IQR 5,40-7,50) (p = 0,0013). El análisis de la curva ROC (AUC 0,804, SE 0,054) dio como óptimo un punto de corte de 5 mm: sensibilidad 90,91%, especificidad 78,79%, VPN 98,1%, VPP 41,7%, OR diagnóstica 37,1 y exactitud diagnóstica 80,52%. El seguimiento medio fue de 18,66 ± 14,35 meses, observándose 3,77% muertes en el grupo con IB < 5 mm y 29,17% en el grupo con IB ≥ 5 mm. Las curvas de supervivencia entre ambos grupos fueron significativamente diferentes (p = 0,0013). Conclusiones. Un punto de corte de IB de 5 mm discrimina de manera adecuada a aquellos pacientes con PET-TC positiva de aquellos con resultado negativo en estadios precoces del melanoma cutáneo, por lo que podría incluirse en la estadificación inicial de este subgrupo de pacientes (AU)

Aim. To establish a Breslow Thickness (BT) cut-off point for indication of PET-CT of cutaneous melanoma in early stages and evaluate its prognostic value. Material and methods. Retrospective analysis of 347 PET-CT studies with diagnosis of melanoma, of which 108 were performed for initial staging. Thirty-one patients were excluded, and a final sample of 77 patients remained. A ROC curve analysis was performed to establish an optimal cut-off point. A survival analysis was performed, considering death assignable to melanoma as the main event, for the evaluation of its prognostic value. Results. Forty-seven (61.04%) of all 77 patients selected were men, and 11 (14.29%) had a positive PET-CT result. Mean age was 65.17 ± 15.00 years. The median BT in patients with a negative PET-CT result was 2.75 mm (IQR 1.83-4.50) and in the positive group 6.25 mm (IQR 5.40-7.50) (P=.0013). In the ROC curve analysis (AUC 0.804, SE 0.054), an optimal value of 5 mm BT with the following values was obtained: sensitivity 90.91%, specificity 78.79%, negative predictive value (NPV) 98.1%, positive predictive value (PPV) 41.7%, diagnostic OR 37.1, and accuracy 80.52%. Mean follow-up was 18.66 ± 14,35 months, detecting 2/53 (3.77%) deaths in the BT < 5 mm group, and 7/24 (29.17%) in the BT≥5 mm group. Survival curves between both groups were significantly different (P=.0013). Conclusions. A 5 mm cut-off point correctly distinguishes those patients with positive PET-CT from those with negative results in the early stages of cutaneous melanoma; therefore it could be included in initial staging of this subgroup of patients (AU)

Calidad diagnóstica y repercusión del empleo de contrastes en los estudios de tomografía computarizada de exploraciones con tomografía por emisión de positrones en combinación con tomografía computarizada / The impact on diagnostic quality of using contrast media in PET-CT studies

Objetivo. Valorar la repercusión del uso de contrastes radiológicos en las exploraciones de tomografía por emisión de positrones en combinación con tomografía computarizada (PET-TC) utilizados en nuestro centro. Material y métodos. Los estudios se realizaron en un equipo PET-TC con una TC multidetector de 6 detectores. La población estudiada fueron pacientes oncológicos. Las indicaciones para realizar estos estudios fueron las incluidas en la ficha técnica de la 18F-2-fluoro-2-desoxi-D-glucosa. Se realizó un estudio retrospectivo observacional con el fin de valorar la calidad de los estudios PET-TC realizados con contrastes radiológicos y la presencia de artefactos generados por estos contrastes. Resultados. Entre febrero y junio de 2009 se han realizado 612 exploraciones PET-TC. Trescientas sesenta y nueve fueron en varones y 243 en mujeres. Se administró contraste iodado intravenoso en el 48% de los pacientes y oral en el 18%. La calidad diagnóstica se valoró como alta en el 93,5% de los estudios, como media en el 4,3% y como baja en el 2,2%. De las TC realizadas con contraste intravenoso se identificaron artefactos por contraste en el 8%, y en el 1,4% ocasionaron dudas diagnósticas en la PET. El contraste oral no produjo problemas diagnósticos en ninguna ocasión. Conclusiones. En el análisis de nuestros estudios hemos observado que el uso de contrastes radiológicos en las exploraciones PET-TC no deteriora la calidad diagnóstica ni altera el flujo de trabajo. Si a esto se añade que una TC de alta calidad diagnóstica puede mejorar la capacidad de detección de la PET-TC nos parece adecuado incluirla en los protocolos de exploración (AU)

Objective. To evaluate the impact of using radiologic contrast media on the quality of PET-CT studies at our center. Material and methods. This is a retrospective observational study to evaluate the quality of the PET-CT studies carried out with radiologic contrast media and the presence of artifacts due to these contrast agents. Oncologic patients in whom PET was indicated according to the manufacturer's specifications for FDG (18F-2-fluoro-2-deoxy-D-glucose) underwent PET-CT study on a PET-CT system with a six-detector-row CT scanner. Results. Between February 2009 and June 2009, we performed 612 PET-CT examinations in 369 male patients and 243 female patients. Iodinated contrast media were administered intravenously in 48% and orally in 18%. Diagnostic quality was considered high in 93.5% of the studies, intermediate in 4.3%, and low in 2.2%. In the CT studies performed using intravenous contrast agents, artifacts were identified in 8% and resulted in diagnostic uncertainty in the PET study in 1.4%. We found no diagnostic problems caused by oral contrast agents in any case. Conclusions. The use of radiologic contrast agents in PET-CT studies does not negatively affect diagnostic quality or workflow. Given that we can improve the ability of PET-CT to detect lesions by enhancing the diagnostic quality of the CT study, we consider it appropriate to include the administration of contrast agents in protocols for PET-CT studies (AU)

Nefroblastomatosis frente a tumor de Wilms: a propósito de un caso / Nephroblastomatosis vs Wilms' tumor: a case report

La nefroblastomatosis es una alteración de la nefrogénesis que se define como la persistencia de blastema metanéfrico en la infancia. La asociación de estos focos de tejido fetal con el tumor de Wilms se encuentra ampliamente documentada en la literatura. En la actualidad disponemos de numerosas técnicas de imagen que van a permitir el diagnóstico y seguimiento de esta entidad, especialmente en los primeros años de vida, cuando el riesgo de malignización es mayor (AU)

Nephroblastomatosis is an abnormality of nephrogenesis and has been defined as the persistence of metanephric blastema into infancy. The association of these foci of fetal tissue with Wilms' tumor has been repeatedly documented in the literature. Numerous imaging modalities currently enable the detection of nephroblastomatosis and follow-up of patients to detect neoplastic change, which is especially indicated during infancy and early childhood, when the likelihood of Wilms' tumor developing is highest (AU)