Whole-body MRI versus an FDG-PET/CT-based reference standard for staging of paediatric Hodgkin lymphoma: a prospective multicentre study

Can Whole-Body Magnetic Resonance Imaging Predict Relapse in Juvenile Idiopathic Arthritis? A Longitudinal Pilot Study

OBJECTIVE

To determine the utility of whole-body magnetic resonance imaging (WB MRI) to predict relapse in children with juvenile idiopathic arthritis (JIA) in clinical remission.

METHODS

Consecutive patients with JIA who fulfilled the Wallace criteria for remission were recruited into this longitudinal pilot study and underwent WB MRI. A radiological score was devised, incorporating synovitis, bone marrow edema, sacroiliitis, enthesitis, and bone erosions. Two readers independently scored the MR data sets. The same score was calculated for both knee joints individually and correlated with outcome for that joint. Score-based models incorporating clinical and laboratory variables were generated. Logistic regression analysis was done to determine predictors for relapse. Receiver operating characteristic curve was drawn for significant variables.

RESULTS

Twenty-two children (median age, 12 years; interquartile range, 9.5-14.25 years) were included in the final analysis. At 24 months' follow-up, 15 joints in 5 children relapsed; knee was the most common site. Seven knee joints had disease relapse. On univariate analysis, synovitis and total score on WB MRI were significant predictors of relapse at follow-up, with odds ratios of 9.46 (bias-corrected 95% confidence interval, 3.07-29.13) and 2.8 (bias-corrected 95% confidence interval, 1.23-6.39) respectively. Two models, which included a higher number of joints involved at presentation and abrupt drug withdrawal strategy as predictor variables, were also statistically significant (odds ratio, approximately 1.9). On multivariate analysis of the predictors variables in models where p < 0.6, it was found that only synovitis score and total score were near statistical significance ( p = 0.06); no clinical or laboratory variables were significant. The areas under the receiver operating characteristic curve for relapse prediction were approximately 0.82, 0.87, 0.79, and 0.81 for synovitis score, total MRI score, and both models, respectively.

CONCLUSION

Synovitis on WB MRI is the strongest independent predictor for disease relapse in children with JIA in remission.

Diagnostic accuracy of whole-body magnetic resonance imaging versus positron emission tomography-computed tomography for the staging of pediatric lymphoma: a systematic review and meta-analysis

BACKGROUND

Whole-body magnetic resonance imaging (MRI) has been investigated by multiple authors as a radiation-free alternative to positron emission tomography computed tomography (PET-CT) in children with lymphoma.

OBJECTIVE

To evaluate the sensitivity, specificity, and diagnostic odds ratio of whole-body MRI compared to PET-CT for the staging of pediatric lymphoma.

METHODS

The databases PubMed, Embase, and Scopus were searched for studies that reported the accuracy of whole-body MRI compared to PET-CT for lymphoma staging in children. Data was collected from included studies to formulate 2 × 2 contingency tables, including the number of true positive, true negative, false positive, and false negative. The pooled sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated. Summary receiver operating characteristic curves were drawn and the area under the curve (AUC) calculated. In addition, the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2) tool was used to assess the risk of bias and applicability concerns.

RESULTS

A total of seven studies were included in the final analysis. Of these, six studies used unenhanced whole-body MRI. The pooled sensitivity of whole-body MRI-based staging was 95.8%, while the pooled specificity was 21.8%. The DOR for whole-body MRI was 1.19. For extranodal staging, the pooled sensitivity was 88.9%, specificity was 97.4%, and DOR was 25.29. The partial AUC for overall staging was 0.63, whereas that for extranodal staging stood at 0.88. Based on the QUADAS 2 tool, all seven studies were at risk of bias (six at high risk, one at unclear risk).

CONCLUSION

Whole-body MRI has high sensitivity for staging of pediatric lymphoma and may be a useful alternative to PET-CT.

[18F]FDG PET/MRI in children suffering from lymphoma: does MRI contrast media make a difference?

OBJECTIVES

Evaluate the influence of an MRI contrast agent application on primary and follow-up staging in pediatric patients with newly diagnosed lymphoma using [18F]FDG PET/MRI to avoid adverse effects and save time and costs during examination.

METHODS

A total of 105 [18F]FDG PET/MRI datasets were included for data evaluation. Two different reading protocols were analyzed by two experienced readers in consensus, including for PET/MRI-1 reading protocol unenhanced T2w and/or T1w imaging, diffusion-weighted imaging (DWI), and [18F]FDG PET imaging and for PET/MRI-2 reading protocol an additional T1w post contrast imaging. Patient-based and region-based evaluation according to the revised International Pediatric Non-Hodgkin's Lymphoma (NHL) Staging System (IPNHLSS) was performed, and a modified standard of reference was applied comprising histopathology and previous and follow-up cross-sectional imaging. Differences in staging accuracy were assessed using the Wilcoxon and McNemar tests.

RESULTS

In patient-based analysis, PET/MRI-1 and PET/MRI-2 both determined a correct IPNHLSS tumor stage in 90/105 (86%) exams. Region-based analysis correctly identified 119/127 (94%) lymphoma-affected regions. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for PET/MRI-1 and PET/MRI-2 were 94%, 97%, 90%, 99%, 97%, respectively. There were no significant differences between PET/MRI-1 and PET/MRI-2.

CONCLUSIONS

The use of MRI contrast agents in [18F]FDG PET/MRI examinations has no beneficial effect in primary and follow-up staging of pediatric lymphoma patients. Therefore, switching to a contrast agent-free [18F]FDG PET/MRI protocol should be considered in all pediatric lymphoma patients.

CLINICAL RELEVANCE STATEMENT

This study gives a scientific baseline switching to a contrast agent-free [18F]FDG PET/MRI staging in pediatric lymphoma patients. This could avoid side effects of contrast agents and saves time and costs by a faster staging protocol for pediatric patients.

KEY POINTS

• No additional diagnostic benefit of MRI contrast agents at [18F]FDG PET/MRI examinations of pediatric lymphoma primary and follow-up staging • Highly accurate primary and follow-up staging of pediatric lymphoma patients at MRI contrast-free [18F]FDG PET/MRI.

The diagnostic value of dual-layer CT in the assessment of lymph nodes in lymphoma patients with PET/CT as a reference standard

This study aimed to evaluate the diagnostic performances of dual-layer CT (DLCT) for the identification of positive lymph nodes (LNs) in patients with lymphoma and retrospectively included 1165 LNs obtained by biopsy from 78 patients with histologically proven lymphoma, who underwent both pretreatment DLCT and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). According to 18F-FDG PET/CT findings as a reference standard, cases were categorized into the LN-negative and LN-positive groups. LNs were then randomly divided at a ratio of 7:3 into the training (n = 809) and validation (n = 356) cohorts. The patients' clinical characteristics and quantitative parameters including spectral curve slope (λHU), iodine concentration (IC) on arterial phase (AP) and venous phase (VP) images were compared between the LN-negative and LN-positive groups using Chi-square test, t-test or Mann-Whitney U test for categorical variables or quantitative parameters. Multivariate logistic regression analysis with tenfold cross-validation was performed to establish the most efficient predictive model in the training cohort. The area under the curve (AUC) was used to evaluate the diagnostic value of the predictive model, and differences in AUC were determined by the DeLong test. Moreover, the predictive model was validated in the validation cohort. Repeatability analysis was performed for LNs using intraclass correlation coefficients (ICCs). In the training cohort, long diameter (LD) had the highest AUC as an independent factors compared to other parameter in differentiating LN positivity from LN negativity (p = 0.006 to p < 0.001), and the AUC of predictive model jointly involving LD and λHU-AP was significantly elevated (AUC of 0.816, p < 0.001). While the AUC of predictive model in the validation cohort was 0.786. Good to excellent repeatability was observed for all parameters (ICC > 0.75). The combination of DLCT with morphological and functional parameters may represent a potential imaging biomarker for detecting LN positivity in lymphoma.

Correlation of mean apparent diffusion coefficient (ADC) and maximal standard uptake value (SUVmax) evaluated by diffusion-weighted MRI and 18F-FDG-PET/CT in children with Hodgkin lymphoma: a feasibility study

BACKGROUND

The objective was to analyse if magnetic resonance imaging (MRI) can act as a non-radiation exposure surrogate for (18)F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in children with histologically confirmed Hodgkin lymphoma (HL) before treatment. This was done by analysing a potential correlation between apparent diffusion coefficient (ADC) in MRI and the maximum standardized uptake value (SUVmax) in FDG-PET/CT.

PATIENTS AND METHODS

Seventeen patients (six female, eleven male, median age: 16 years, range: 12-20 years) with histologically confirmed HL were retrospectively analysed. The patients underwent both MRI and (18)F-FDG PET/CT before the start of treatment. (18)F-FDG PET/CT data and correlating ADC maps in MRI were collected. For each HL-lesion two readers independently evaluated the SUVmax and correlating meanADC.

RESULTS

The seventeen patients had a total of 72 evaluable lesions of HL and there was no significant difference in the number of lesions between male and female patients (median male: 15, range: 12-19 years, median female: 17 range: 12-18 years, p = 0.021). The mean duration between MRI and PET/CT was 5.9 ± 5.3 days. The inter-reader agreement as assessed by the intraclass correlation coefficient (ICC) was excellent (ICC = 0.98, 95% CI: 0.97-0.99). The correlated SUVmax and meanADC of all 17 patients (ROIs n = 72) showed a strong negative correlation of -0.75 (95% CI: -0.84, - -0.63, p = 0.001). Analysis revealed a difference in the correlations of the examination fields. The correlated SUVmax and meanADC showed a strong correlation at neck and thoracal examinations (neck: -0.83, 95% CI: -0.93, - -0.63, p < 0.0001, thoracal: -0.82, 95% CI: -0.91, - -0.64, p < 0.0001) and a fair correlation at abdominal examinations of -0.62 (95% CI: -0.83, - -0.28, p = 0.001).

CONCLUSIONS

SUVmax and meanADC showed a strong negative correlation in paediatric HL lesions. The assessment seemed robust according to inter-reader agreements. Our results suggest that ADC maps and meanADC have the potential to replace PET/CT in the analysis of disease activity in paediatric Hodgkin lymphoma patients. This may help reduce the number of PET/CT examinations and decrease radiation exposure to children.

Whole body MRI with Diffusion Weighted Imaging versus 18F-fluorodeoxyglucose-PET/CT in the staging of lymphomas

PURPOSE

To assess the diagnostic performance of Whole Body (WB)-MRI in comparison with 18F-Fluorodeoxyglucose-PET/CT (18F-FDG-PET/CT) in lymphoma staging and to assess whether quantitative metabolic parameters from 18F-FDG-PET/CT and Apparent Diffusion Coefficient (ADC) values are related.

MATERIALS AND METHODS

We prospectively enrolled patients with a histologically proven primary nodal lymphoma to  undergo 18F-FDG-PET/CT and WB-MRI, both performed within 15 days one from the other, either before starting treatment (baseline) or during treatment (interim). Positive and negative predictive values of WB-MRI for the identification of nodal and extra-nodal disease were measured. The agreement between WB-MRI and 18F-FDG-PET/CT for the identification of lesions and staging was assessed through Cohen's coefficient k and observed agreement. Quantitative parameters of nodal lesions derived from 18F-FDG-PET/CT and WB-MRI (ADC) were measured and the Pearson or Spearman correlation coefficient was used to assess the correlation between them. The specified level of significance was p ≤ 0.05.

RESULTS

Among the 91 identified patients, 8 refused to participate and 22 met exclusion criteria, thus images from 61 patients (37 men, mean age 30.7 years) were evaluated. The agreement between 18F-FDG-PET/CT and WB-MRI for the identification of nodal and extra-nodal lesions was 0.95 (95% CI 0.92 to 0.98) and 1.00 (95% CI NA), respectively; for staging it was 1.00 (95% CI NA). A strong negative correlation was found between ADCmean and SUVmean of nodal lesions in patients evaluated at baseline (Spearman coefficient r_s = - 0.61, p = 0.001).

CONCLUSION

WB-MRI has a good diagnostic performance for staging of patients with lymphoma in comparison with 18F-FDG-PET/CT and is a promising technique for the quantitative assessment of disease burden in these patients.

Simultaneous multislice diffusion-weighted imaging versus standard diffusion-weighted imaging in whole-body PET/MRI

OBJECTIVE

To compare standard (STD-DWI) single-shot echo-planar imaging DWI and simultaneous multislice (SMS) DWI during whole-body positron emission tomography (PET)/MRI regarding acquisition time, image quality, and lesion detection.

METHODS

Eighty-three adults (47 females, 57%), median age of 64 years (IQR 52-71), were prospectively enrolled from August 2018 to March 2020. Inclusion criteria were (a) abdominal or pelvic tumors and (b) PET/MRI referral from a clinician. Patients were excluded if whole-body acquisition of STD-DWI and SMS-DWI sequences was not completed. The evaluated sequences were axial STD-DWI at b-values 50-400-800 s/mm2 and the apparent diffusion coefficient (ADC), and axial SMS-DWI at b-values 50-300-800 s/mm2 and ADC, acquired with a 3-T PET/MRI scanner. Three radiologists rated each sequence's quality on a five-point scale. Lesion detection was quantified using the anatomic MRI sequences and PET as the reference standard. Regression models were constructed to quantify the association between all imaging outcomes/scores and sequence type.

RESULTS

The median whole-body STD-DWI acquisition time was 14.8 min (IQR 14.1-16.0) versus 7.0 min (IQR 6.7-7.2) for whole-body SMS-DWI, p < 0.001. SMS-DWI image quality scores were higher than STD-DWI in the abdomen (OR 5.31, 95% CI 2.76-10.22, p < 0.001), but lower in the cervicothoracic junction (OR 0.21, 95% CI 0.10-0.43, p < 0.001). There was no significant difference in the chest, mediastinum, pelvis, and rectum. STD-DWI detected 276/352 (78%) lesions while SMS-DWI located 296/352 (84%, OR 1.46, 95% CI 1.02-2.07, p = 0.038).

CONCLUSIONS

In cancer staging and restaging, SMS-DWI abbreviates acquisition while maintaining or improving the diagnostic yield in most anatomic regions.

KEY POINTS

• Simultaneous multislice diffusion-weighted imaging enables faster whole-body image acquisition. • Simultaneous multislice diffusion-weighted imaging maintains or improves image quality when compared to single-shot echo-planar diffusion-weighted imaging in most anatomical regions. • Simultaneous multislice diffusion-weighted imaging leads to superior lesion detection.

Whole-body MRI in children: state of the art

Whole-body magnetic resonance imaging (WBMRI) is an increasingly popular technique in paediatric imaging. It provides high-resolution anatomical information, with the potential for further exciting developments in acquisition of functional data with advanced MR sequences and hybrid imaging with radionuclide tracers. WBMRI demonstrates the extent of disease in a range of multisystem conditions and, in some cases, disease burden prior to the onset of clinical features. The current applications of WBMRI in children are hereby reviewed, along with suggested anatomical stations and sequence protocols for acquisition.

A comparison of FDG PET/MR and PET/CT for staging, response assessment, and prognostic imaging biomarkers in lymphoma

The aim of the current study was to investigate the diagnostic performance of FDG PET/MR compared to PET/CT in a patient cohort including Hodgkins lymphoma, diffuse large B-cell lymphoma, and high-grade B-cell lymphoma at baseline and response assessment. Sixty-one patients were examined with FDG PET/CT directly followed by PET/MR. Images were read by two pairs of nuclear medicine physicians and radiologists. Concordance for lymphoma involvement between PET/MR and the reference standard PET/CT was assessed at baseline and response assessment. Correlation of prognostic biomarkers Deauville score, criteria of response, SUVmax, SUVpeak, and MTV was performed between PET/MR and PET/CT. Baseline FDG PET/MR showed a sensitivity of 92.5% and a specificity 97.9% compared to the reference standard PET/CT (κ 0.91) for nodal sites. For extranodal sites, a sensitivity of 80.4% and a specificity of 99.5% were found (κ 0.84). Concordance in Ann Arbor was found in 57 of 61 patients (κ 0.92). Discrepancies were due to misclassification of region and not lesion detection. In response assessment, a sensitivity of 100% and a specificity 99.9% for all sites combined were found (κ 0.92). There was a perfect agreement on Deauville scores 4 and 5 and criteria of response between the two modalities. Intraclass correlation coefficient (ICC) for SUVmax, SUVpeak, and MTV values showed excellent reliability (ICC > 0.9). FDG PET/MR is a reliable alternative to PET/CT in this patient population, both in terms of lesion detection at baseline staging and response assessment, and for quantitative prognostic imaging biomarkers.

Whole-body MRI versus an [18F]FDG-PET/CT-based reference standard for early response assessment and restaging of paediatric Hodgkin's lymphoma: a prospective multicentre study

OBJECTIVES

To compare WB-MRI with an [18F]FDG-PET/CT-based reference for early response assessment and restaging in children with Hodgkin's lymphoma (HL).

METHODS

Fifty-one children (ages 10-17) with HL were included in this prospective, multicentre study. All participants underwent WB-MRI and [18F]FDG-PET/CT at early response assessment. Thirteen of the 51 patients also underwent both WB-MRI and [18F]FDG-PET/CT at restaging. Two radiologists independently evaluated all WB-MR images in two separate readings: without and with DWI. The [18F]FDG-PET/CT examinations were evaluated by a nuclear medicine physician. An expert panel assessed all discrepancies between WB-MRI and [18F]FDG-PET/CT to derive the [18F]FDG-PET/CT-based reference standard. Inter-observer agreement for WB-MRI was calculated using kappa statistics. Concordance, PPV, NPV, sensitivity and specificity for a correct assessment of the response between WB-MRI and the reference standard were calculated for both nodal and extra-nodal disease presence and total response evaluation.

RESULTS

Inter-observer agreement of WB-MRI including DWI between both readers was moderate (κ 0.46-0.60). For early response assessment, WB-MRI DWI agreed with the reference standard in 33/51 patients (65%, 95% CI 51-77%) versus 15/51 (29%, 95% CI 19-43%) for WB-MRI without DWI. For restaging, WB-MRI including DWI agreed with the reference standard in 9/13 patients (69%, 95% CI 42-87%) versus 5/13 patients (38%, 95% CI 18-64%) for WB-MRI without DWI.

CONCLUSIONS

The addition of DWI to the WB-MRI protocol in early response assessment and restaging of paediatric HL improved agreement with the [18F]FDG-PET/CT-based reference standard. However, WB-MRI remained discordant in 30% of the patients compared to standard imaging for assessing residual disease presence.

KEY POINTS

• Inter-observer agreement of WB-MRI including DWI between both readers was moderate for (early) response assessment of paediatric Hodgkin's lymphoma. • The addition of DWI to the WB-MRI protocol in early response assessment and restaging of paediatric Hodgkin's lymphoma improved agreement with the [18F]FDG-PET/CT-based reference standard. • WB-MRI including DWI agreed with the reference standard in respectively 65% and 69% of the patients for early response assessment and restaging.

Femoral marrow MRI is a non-invasive, non-irradiated and useful tool for detecting bone marrow involvement in non-Hodgkin lymphoma

Femoral marrow magnetic resonance imaging (MRI) is a non-invasive, non-irradiated and useful modality for evaluating bone marrow (BM) conditions. Human adult femoral BM is almost uniformly fatty marrow and has the largest volume of a single bone. MRI has an extremely high resolution for fat and water, which allows high-contrast imaging of cellular infiltration into fat tissue. In hematological diseases, femoral BM MRI can clearly detect cell infiltration, which is symmetrically imaged from the proximal to the distal direction of abnormal signal areas. Thus, we investigated the significance of femoral MRI for non-Hodgkin lymphoma (NHL). We analyzed the data of 69 NHL patients who received femoral MRI at diagnosis in this single-center retrospective cohort study. The median patient age was 73 years. MRI patterns were mainly classified as uniform patterns or nonuniform patterns. We also classified the range of cellular marrow as high-grade or low-grade based on whether it had spread to over half of the femur. Both overall survival (OS) and progression-free survival (PFS) were significantly influenced by abnormal femoral marrow MRI. In particular, the patients with cellular femoral marrow lesions had a worse OS and PFS based on log-rank tests. Multivariable analyses with the Cox proportional hazards model revealed that OS and PFS were significantly influenced by cellular marrow diagnosed by femoral MRI. We concluded that femoral marrow MRI is a useful tool for detecting BM involvement and an independent prognostic factor in NHL patients.