Quantitative diffusion-weighted MRI response assessment in rhabdomyosarcoma: an international retrospective study on behalf of the European paediatric Soft tissue sarcoma Study Group Imaging Committee.

OBJECTIVE: To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) as a predictive imaging marker after neoadjuvant chemotherapy in patients with rhabdomyosarcoma. MATERIAL AND METHODS: We performed a multicenter retrospective study including pediatric, adolescent and young adult patients with rhabdomyosarcoma, Intergroup Rhabdomyosarcoma Study group III/IV, treated according to the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS2005 or MTS2008 studies. DW-MRI was performed according to institutional protocols. We performed two-dimensional single-slice tumor delineation. Areas of necrosis or hemorrhage were delineated to be excluded in the primary analysis. Mean, median and 5th and 95th apparent diffusion coefficient (ADC) were extracted. RESULTS: Of 134 included patients, 82 had measurable tumor at diagnosis and response and DW-MRI scans of adequate quality and were included in the analysis. Technical heterogeneity in scan acquisition protocols and scanners was observed. Mean ADC at diagnosis was 1.1 (95% confidence interval [CI]: 1.1-1.2) (all ADC expressed in * 10-3 mm2/s), versus 1.6 (1.5-1.6) at response assessment. The 5th percentile ADC was 0.8 (0.7-0.9) at diagnosis and 1.1 (1.0-1.2) at response. Absolute change in mean ADC after neoadjuvant chemotherapy was 0.4 (0.3-0.5). Exploratory analyses for association between ADC and clinical parameters showed a significant difference in mean ADC at diagnosis for alveolar versus embryonal histology. Landmark analysis at nine weeks after the date of diagnosis showed no significant association (hazard ratio 1.3 [0.6-3.2]) between the mean ADC change and event-free survival. CONCLUSION: A significant change in the 5th percentile and the mean ADC after chemotherapy was observed. Strong heterogeneity was identified in DW-MRI acquisition protocols between centers and in individual patients.

ORGAN DOSE ESTIMATION ACCOUNTING FOR UNCERTAINTY FOR PEDIATRIC AND YOUNG ADULT CT SCANS IN THE UNITED KINGDOM.

Since our previous publication of organ dose for the pediatric CT cohort in the UK, there have been questions about the magnitude of uncertainty in our dose estimates. We therefore quantified shared and unshared uncertainties in empirical CT parameters extracted from 1073 CT films (1978-2008) from 36 hospitals in the study and propagated these uncertainties into organ doses using Monte Carlo random sampling and NCICT organ dose calculator. The average of 500 median brain and marrow doses for the full cohort was 35 (95% confidence interval: 30-40) mGy and 6 (5-7) mGy, respectively. We estimated that shared uncertainty contributed ~99% of coefficient of variation of median brain doses in brain scans compared to unshared uncertainty (1% contribution). We found that the previous brain doses were slightly underestimated for <1990 and overestimated for >1990 compared to the results in the current study due to the revised CTDI models based on CT films.

Relationship between paediatric CT scans and subsequent risk of leukaemia and brain tumours: assessment of the impact of underlying conditions.

BACKGROUND: We previously reported evidence of a dose-response relationship between ionising-radiation exposure from paediatric computed tomography (CT) scans and the risk of leukaemia and brain tumours in a large UK cohort. Underlying unreported conditions could have introduced bias into these findings. METHODS: We collected and reviewed additional clinical information from radiology information systems (RIS) databases, underlying cause of death and pathology reports. We conducted sensitivity analyses excluding participants with cancer-predisposing conditions or previous unreported cancers and compared the dose-response analyses with our original results. RESULTS: We obtained information from the RIS and death certificates for about 40% of the cohort (n∼180 000) and found cancer-predisposing conditions in 4 out of 74 leukaemia/myelodysplastic syndrome (MDS) cases and 13 out of 135 brain tumour cases. As these conditions were unrelated to CT exposure, exclusion of these participants did not alter the dose-response relationships. We found evidence of previous unreported cancers in 2 leukaemia/MDS cases, 7 brain tumour cases and 232 in non-cases. These previous cancers were related to increased number of CTs. Exclusion of these cancers reduced the excess relative risk per mGy by 15% from 0.036 to 0.033 for leukaemia/MDS (P-trend=0.02) and by 30% from 0.023 to 0.016 (P-trend<0.0001) for brain tumours. When we included pathology reports we had additional clinical information for 90% of the cases. Additional exclusions from these reports further reduced the risk estimates, but this sensitivity analysis may have underestimated risks as reports were only available for cases. CONCLUSIONS: Although there was evidence of some bias in our original risk estimates, re-analysis of the cohort with additional clinical data still showed an increased cancer risk after low-dose radiation exposure from CT scans in young patients.

Assessment of Primary Site Response in Children With High-Risk Neuroblastoma: An International Multicenter Study.

PURPOSE: The International Neuroblastoma Response Criteria (INRC) require serial measurements of primary tumors in three dimensions, whereas the Response Evaluation Criteria in Solid Tumors (RECIST) require measurement in one dimension. This study was conducted to identify the preferred method of primary tumor response assessment for use in revised INRC. PATIENTS AND METHODS: Patients younger than 20 years with high-risk neuroblastoma were eligible if they were diagnosed between 2000 and 2012 and if three primary tumor measurements (antero-posterior, width, cranio-caudal) were recorded at least twice before resection. Responses were defined as ≥ 30% reduction in longest dimension as per RECIST, ≥ 50% reduction in volume as per INRC, or ≥ 65% reduction in volume. RESULTS: Three-year event-free survival for all patients (N = 229) was 44% and overall survival was 58%. The sensitivity of both volume response measures (ability to detect responses in patients who survived) exceeded the sensitivity of the single dimension measure, but the specificity of all response measures (ability to identify lack of response in patients who later died) was low. In multivariable analyses, none of the response measures studied was predictive of outcome, and none was predictive of the extent of resection. CONCLUSION: None of the methods of primary tumor response assessment was predictive of outcome. Measurement of three dimensions followed by calculation of resultant volume is more complex than measurement of a single dimension. Primary tumor response in children with high-risk neuroblastoma should therefore be evaluated in accordance with RECIST criteria, using the single longest dimension.

Response assessment in pediatric rhabdomyosarcoma: can response evaluation criteria in solid tumors replace three-dimensional volume assessments?

PURPOSE: To investigate (a) interobserver variability for three-dimensional (3D) (based on European Pediatric Soft-Tissue Sarcoma Study Group [EpSSG] guidelines) and one-dimensional (1D) (based on Response Evaluation Criteria in Solid Tumors [RECIST]) response assessments, (b) intermethod variability between EpSSG guidelines and RECIST, and (c) clinically relevant consequences of interobserver and intermethod variability in pediatric patients with rhabdomyosarcoma. MATERIALS AND METHODS: The study was approved by the Academic Medical Center Ethics Committee and the Great Ormond Street Hospital Ethics Committee; both committees waived the requirement for informed consent because of the retrospective nature of the study. Data were analyzed from 124 consecutive male and female children and young adults (age range, 1-18 years) with rhabdomyosarcoma at two institutions (1999-2009) with relevant imaging studies. Tumors were measured by two radiologists (1D and 3D measurements) at diagnosis and after induction chemotherapy. Interobserver variability was analyzed by using three different tests, and the intermethod variation was calculated. RESULTS: Sixty-four eligible patients were included (median age, 4.6 years). Agreement between observers for EpSSG guidelines and RECIST was moderate (κ = 0.565 and 0.592, respectively); interobserver variation led to different potential treatment decisions in nine (14%) and 11 (17%) of the 64 patients, respectively. Comparison of EpSSG guidelines and RECIST resulted in 13 discrepant response classifications (20%), which were equally distributed (under- and overestimation of response) and led to consequences for treatment choice in five patients (8%). CONCLUSION: EpSSG guidelines and RECIST are not interchangeable; neither technique demonstrated superiority in this study. These findings should be taken into account in future study protocol design. Online supplemental material is available for this article.

Socio-economic variation in CT scanning in Northern England, 1990-2002.

BACKGROUND: Socio-economic status is known to influence health throughout life. In childhood, studies have shown increased injury rates in more deprived settings. Socio-economic status may therefore be related to rates of certain medical procedures, such as computed tomography (CT) scans. This study aimed to assess socio-economic variation among young people having CT scans in Northern England between 1990 and 2002 inclusive. METHODS: Electronic data were obtained from Radiology Information Systems of all nine National Health Service hospital Trusts in the region. CT scan data, including sex, date of scan, age at scan, number and type of scans were assessed in relation to quintiles of Townsend deprivation scores, obtained from linkage of postcodes with census data, using χ2 tests and Spearman rank correlations. RESULTS: During the study period, 39,676 scans were recorded on 21,089 patients, with 38,007 scans and 19,485 patients (11344 male and 8132 female) linkable to Townsend scores. The overall distributions of both scans and patients by quintile of Townsend deprivation scores were significantly different to the distributions of Townsend scores from the census wards included in the study (p < 0.0001). There was a significant association between type of scan and deprivation quintile (p < 0.0001), primarily due to the higher proportions of head scans in the three most deprived quintiles, and slightly higher proportions of chest scans and abdomen and pelvis scans in the least deprived groups. There was also a significant association (p < 0.0001) between the patient's age at the time of the CT scan and Townsend deprivation quintiles, with slightly increasing proportions of younger children with increasing deprivation. A similar association with age (p < 0.0001) was seen when restricting the data to include only the first scan of each patient. The number of scans per patient was also associated with Townsend deprivation quintiles (p = 0.014). CONCLUSIONS: Social inequalities exist in the numbers of young people undergoing CT scans with those from deprived areas more likely to do so. This may reflect the rates of injuries in these individuals and implies that certain groups within the population may receive higher radiation doses than others due to medical procedures.

How accurate is dynamic contrast-enhanced MRI in the assessment of renal glomerular filtration rate? A critical appraisal.

PURPOSE: To evaluate the current literature to see if the published results of MRI-glomerular filtration rate (GFR) stand up to the claim that MRI-GFR may be used in clinical practice. Claims in the current literature that Gadolinium (Gd) DTPA dynamic contrast enhanced (DCE) MRI clearance provides a reliable estimate of glomerular filtration are an overoptimistic interpretation of the results obtained. Before calculating absolute GFR from Gd-enhanced MRI, numerous variables must be considered. MATERIALS AND METHODS: We examine the methodology in the published studies on absolute quantification of MRI-GFR. The techniques evaluated included the dose and volume of Gd-DTPA used, the speed of injection, acquisition sequences, orientation of the subject, re-processing, conversion of signal to concentration and the model used for analysis of the data as well as the MRI platform. RESULTS: Claims in the current literature that using DCE MRI "Gd DTPA clearance provides a good estimate of glomerular filtration" are not supported by the data presented and a more accurate conclusion should be that "no MRI approach used provides a wholly satisfactory measure of renal GFR function." CONCLUSION: This study suggests that DCE MRI-GFR results are not yet able to be used as a routine clinical or research tool. The published literature does not show what change in DCE MRI-GFR is clinically significant, nor do the results in the literature allow a single DCE MRI-GFR measurement to be correlated directly with a multiple blood sampling technique.

Ultrasound evaluation of liver disease in cystic fibrosis as part of an annual assessment clinic: a 9-year review.

AIM: To review 9 years of annual assessment data in cystic fibrosis (CF) and evaluate the frequency of hepatobiliary abnormalities and the correlation between ultrasound and biochemical findings. MATERIALS AND METHODS: Over a 9-year period (1990-99), 168 children (age range 1-18 years) with CF have undergone an annual assessment which has included clinical, biochemical and ultrasonographic evaluation of the hepatobiliary system. We have retrospectively reviewed the sequential ultrasound reports and correlated them with the contemporaneous biochemical results. RESULTS: A total of 725 ultrasound examinations were performed over the review period. Sixty patients had at least one examination showing an abnormality of liver echo texture and in 39 patients this was a persisting finding. Seven patients (4.2%) developed frank cirrhotic change on ultrasound criteria, while 15 patients (8.9%) had evidence of persistent splenomegaly. Gall-bladder calculi were present in 4.8%. In 176 examinations (24%) there was disparity between the ultrasound findings and aspartate aminotransferase (AST) levels. In 3.0% of cases (five patients) there were persisting abnormalities of liver echo texture and persisting splenomegaly with a normal range AST value. CONCLUSION: No perfect method of assessing hepatobiliary involvement in CF is currently available. Ultrasonographic and biochemical assessment may reflect different aspects of disease progression. Routine use of ultrasound in annual assessment allows identification of a minority of patients with liver changes but with normal biochemistry.