Whole-body MRI for staging and interim response monitoring in paediatric and adolescent Hodgkin's lymphoma: a comparison with multi-modality reference standard including 18F-FDG-PET-CT

Comparison of diffusion-weighted MRI and [18F]FDG PET/MRI for treatment monitoring in pediatric Hodgkin and non-Hodgkin lymphoma

OBJECTIVE

To compare tumor therapy response assessments with whole-body diffusion-weighted imaging (WB-DWI) and 18F-fluorodeoxyglucose ([18F]FDG) PET/MRI in pediatric patients with Hodgkin lymphoma and non-Hodgkin lymphoma.

MATERIALS AND METHODS

In a retrospective, non-randomized single-center study, we reviewed serial simultaneous WB-DWI and [18F]FDG PET/MRI scans of 45 children and young adults (27 males; mean age, 13 years ± 5 [standard deviation]; age range, 1-21 years) with Hodgkin lymphoma (n = 20) and non-Hodgkin lymphoma (n = 25) between February 2018 and October 2022. We measured minimum tumor apparent diffusion coefficient (ADCmin) and maximum standardized uptake value (SUVmax) of up to six target lesions and assessed therapy response according to Lugano criteria and modified criteria for WB-DWI. We evaluated the agreement between WB-DWI- and [18F]FDG PET/MRI-based response classifications with Gwet's agreement coefficient (AC).

RESULTS

After induction chemotherapy, 95% (19 of 20) of patients with Hodgkin lymphoma and 72% (18 of 25) of patients with non-Hodgkin lymphoma showed concordant response in tumor metabolism and proton diffusion. We found a high agreement between treatment response assessments on WB-DWI and [18F]FDG PET/MRI (Gwet's AC = 0.94; 95% confidence interval [CI]: 0.82, 1.00) in patients with Hodgkin lymphoma, and a lower agreement for patients with non-Hodgkin lymphoma (Gwet's AC = 0.66; 95% CI: 0.43, 0.90). After completion of therapy, there was an excellent agreement between WB-DWI and [18F]FDG PET/MRI response assessments (Gwet's AC = 0.97; 95% CI: 0.91, 1).

CONCLUSION

Therapy response of Hodgkin lymphoma can be evaluated with either [18F]FDG PET or WB-DWI, whereas patients with non-Hodgkin lymphoma may benefit from a combined approach.

CLINICAL RELEVANCE STATEMENT

Hodgkin lymphoma and non-Hodgkin lymphoma exhibit different patterns of tumor response to induction chemotherapy on diffusion-weighted MRI and PET/MRI.

KEY POINTS

• Diffusion-weighted imaging has been proposed as an alternative imaging to assess tumor response without ionizing radiation. • After induction therapy, whole-body diffusion-weighted imaging and PET/MRI revealed a higher agreement in patients with Hodgkin lymphoma than in those with non-Hodgkin lymphoma. • At the end of therapy, whole-body diffusion-weighted imaging and PET/MRI revealed an excellent agreement for overall tumor therapy responses for all lymphoma types.

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.

Significance of E-lesions in Hodgkin lymphoma and the creation of a new consensus definition: a report from SEARCH

The International Staging Evaluation and Response Criteria Harmonization for Childhood, Adolescent, and Young Adult Hodgkin Lymphoma (SEARCH for CAYAHL) seeks to provide an appropriate, universal differentiation between E-lesions and stage IV extranodal disease in Hodgkin lymphoma (HL). A literature search was performed through the PubMed and Google Scholar databases using the terms "Hodgkin disease," and "extranodal," "extralymphatic," "E lesions," "E stage," or "E disease." Publications were reviewed for the number of participants; median age and age range; diagnostic modalities used for staging; and the definition, incidence, and prognostic significance of E-lesions. Thirty-six articles describing 12 640 patients met the inclusion criteria. Most articles reported staging per the Ann Arbor (72%, 26/36) or Cotswolds modification of the Ann Arbor staging criteria (25%, 9/36), and articles rarely defined E-lesions or disambiguated "extranodal disease." The overall incidence of E-lesions for patients with stage I-III HL was 11.5% (1330/11 602 unique patients). Available stage-specific incidence analysis of 3888 patients showed a similar incidence of E-lesions in stage II (21.2%) and stage III (21.9%), with E-lesions rarely seen with stage I disease (1.1%). E-lesions likely remain predictive, but we cannot unequivocally conclude that identifying E-lesions in HL imparts prognostic value in the modern era of the more selective use of targeted radiation therapy. A harmonized E-lesion definition was reached based on the available evidence and the consensus of the SEARCH working group. We recommend that this definition of E-lesion be applied in future clinical trials with explicit reporting to confirm the prognostic value of E-lesions.

MRI-based long-term follow-up of indolent orbital lymphomas after curative radiotherapy: imaging remission criteria and volumetric regression kinetics

We systematically analyzed the kinetics of tumor regression, the impact of residual lesions on disease control and the applicability of the Lugano classification in follow-up MRI of orbital non-Hodgkin lymphomas that were irradiated with photons. We retrospectively analyzed a total of 154 pre- and post-irradiation MRI datasets of 36 patients with low-grade, Ann-Arbor stage I, orbital non-Hodgkin lymphomas. Patients with restricted conjunctival involvement were excluded. Lymphoma lesions were delineated and volumetrically analyzed on T1-weighted sequences. Tumor residues were present in 91.2% of all cases during the first six months after treatment. Volumetric partial response rates (> 50% volume reduction) were 75%, 69.2%, and 50% at 12-24 months, 36-48 months and > 48 months after the end of treatment. The corresponding complete response (CR) rates according to the Lugano classification were 20%, 23.1% and 50%. During a median clinical follow-up of 37 months no significant differences in progression free survival (PFS) rates were observed between the CR and non-CR group (p = 0.915). A residual tumor volume below 20% of the pretreatment volume should be expected at long-term follow-up beyond one year after radiotherapy.

Diagnostic performance of prospective same-day 18F-FDG PET/MRI and 18F-FDG PET/CT in the staging and response assessment of lymphoma

BACKGROUND

Accurate staging and response assessment are essential for prognosis and to guide treatment in patients with lymphoma. The aim of this study was to compare the diagnostic performance of FDG PET/MRI versus FDG PET/CT in adult patients with newly diagnosed Hodgkin and Non- Hodgkin lymphoma.

METHODS

In this single centre study, 50 patients were prospectively recruited. FDG PET/MRI was performed after staging FDG PET/CT using a single injection of 18F-FDG. Patients were invited to complete same-day FDG PET/MRI with FDG PET/CT at interim and end of treatment response assessments. Performance was assessed using PET/CT as the reference standard for disease site identification, staging, response assessment with Deauville score and concordance in metabolic activity.

RESULTS

Staging assessment showed perfect agreement (κ = 1.0, P = 0) between PET/MRI and PET/CT using Ann Arbor staging. There was excellent intermodality correlation with disease site identification at staging (κ = 0.976, P < 0.001) with FDG PET/MRI sensitivity of 96% (95% CI, 94-98%) and specificity of 100% (95% CI, 99-100%). There was good correlation of disease site identification at interim assessment (κ = 0.819, P < 0.001) and excellent correlation at end-of-treatment assessment (κ = 1.0, P < 0.001). Intermodality agreement for Deauville scores was good at interim assessment (κ = 0.808, P < 0.001) and excellent at end-of-treatment assessment (κ = 1.0, P = 0). There was good-excellent concordance in SUV max and mean between modalities across timepoints. Minimum calculated radiation patient effective dose saving was 54% between the two modalities per scan.

CONCLUSION

With high concordance in disease site identification, staging and response assessment, PET/MR is a potentially viable alternative to PET/CT in lymphoma that minimises radiation exposure.

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.

Whole-Body MRI Is an Effective Imaging Modality for Hematological Malignancy Treatment Response Assessment: A Systematic Review and Meta-Analysis

OBJECTIVES

To evaluate the diagnostic accuracy of whole-body MRI (WB-MRI) for assessment of hematological malignancies' therapeutic response.

METHODS

PubMed, Embase, and Web of Science were searched up to August 2021 to identify studies reporting the diagnostic performance of WB-MRI for the assessment of hematological malignancies' treatment response. A bivariate random-effects model was applied for the generation of the pooled diagnostic performance.

RESULTS

Fourteen studies with 457 patients with lymphoma, multiple myeloma, and sarcoma (very small proportion) were analyzed. Overall pooled sensitivity and specificity of WB-MRI were 0.88 (95% CI: 0.73-0.95) and 0.86 (95% CI: 0.73-0.93), respectively. Studies using whole-body diffusion-weighted imaging (WB-DWI) showed higher sensitivity than those that did not (0.94 vs. 0.55, p = 0.02). The pooled concordance rate of WB-MRI to assess hematological malignancies' treatment response with reference standard was 0.78 (95% CI: 0.59-0.96). WB-MRI and PET/CT showed similar diagnostic performance (sensitivity [0.83 vs. 0.92, p = 0.11] and specificity [0.87 vs. 0.76, p = 0.73]).

CONCLUSION

WB-MRI has high diagnostic performance for hematological malignancies' treatment response assessment. The adding of WB-DWI is strongly associated with increased sensitivity.

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.

18F-FDG PET/MRI for Staging and Interim Response Assessment in Pediatric and Adolescent Hodgkin Lymphoma: A Prospective Study with 18F-FDG PET/CT as the Reference Standard

Treatment regimens for pediatric Hodgkin lymphoma (HL) depend on accurate staging and treatment response assessment, based on accurate disease distribution and metabolic activity depiction. With the aim of radiation dose reduction, we compared the diagnostic performance of 18F-FDG PET/MRI with a 18F-FDG PET/CT reference standard for staging and response assessment. Methods: Twenty-four patients (mean age, 15.4 y; range, 8-19.5 y) with histologically proven HL were prospectively and consecutively recruited in 2015 and 2016, undergoing both 18F-FDG PET/CT and 18F-FDG PET/MRI at initial staging (n = 24) and at response assessment (n = 21). The diagnostic accuracy of 18F-FDG PET/MRI for both nodal and extranodal disease was compared with that of 18F-FDG PET/CT, which was considered the reference standard. Discrepancies were retrospectively classified as perceptual or technical errors, and 18F-FDG PET/MRI and 18F-FDG PET/CT were corrected by removing perceptual error. Agreement with Ann Arbor staging and Deauville grading was also assessed. Results: For nodal and extranodal sites combined, corrected staging 18F-FDG PET/MRI sensitivity was 100% (95% CI, 96.7%-100%) and specificity was 99.5% (95% CI, 98.3%-99.9%). Corrected response-assessment 18F-FDG PET/MRI sensitivity was 83.3% (95% CI, 36.5%-99.1%) and specificity was 100% (95% CI, 99.2%-100%). Modified Ann Arbor staging agreement between 18F-FDG PET/CT and 18F-FDG PET/MRI was perfect (κ = 1.0, P = 0.000). Deauville grading agreement between 18F-FDG PET/MRI and 18F-FDG PET/CT was excellent (κ = 0.835, P = 0.000). Conclusion:18F-FDG PET/MRI is a promising alternative to 18F-FDG PET/CT for staging and response assessment in children with HL.

Whole-body magnetic resonance imaging for the diagnosis of metastasis in children and adolescents: a systematic review and meta-analysis

Whole-body magnetic resonance imaging (WB-MRI) is a noninvasive imaging method that can be used to diagnose and stage tumors, as well as to assess therapeutic responses in oncology. The objective of this meta-analysis was to evaluate the accuracy of WB-MRI for the diagnosis of metastases in pediatric patients. The following electronic databases were searched: Medline, Embase, Cochrane Central Register of Controlled Trials, Scientific Electronic Library Online, Latin-American and Caribbean Health Sciences Literature, Cumulative Index to Nursing and Allied Health Literature, Web of Science, and ClinicalTrials.gov. All of the selected studies included children and adolescents with histopathological confirmation of a primary tumor. Collectively, the studies included 118 patients ranging in age from 7 months to 19 years. The pooled sensitivity and specificity of WB-MRI were, respectively, 0.964 (95% CI: 0.944-0.978; I² = 0%) and 0.902 (95% CI: 0.882-0.919; I² = 98.4%), with an area under the curve (AUC) of 0.991. We found that WB-MRI had good accuracy for the diagnosis of metastases in pediatric patients and could therefore provide an alternative to complete the staging of tumors in such patients, being a safer option because it does not involve the use of ionizing radiation.

Whole-Body Magnetic Resonance Imaging: Current Role in Patients with Lymphoma

Imaging of lymphoma is based on the use of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) and/or contrast-enhanced CT, but concerns have been raised regarding radiation exposure related to imaging scans in patients with cancer, and its association with increased risk of secondary tumors in patients with lymphoma has been established. To date, lymphoproliferative disorders are among the most common indications to perform whole-body magnetic resonance imaging (MRI). Whole-body MRI is superior to contrast-enhanced CT for staging the disease, also being less dependent on histology if compared to ¹⁸F-FDG-PET/CT. As well, it does not require exposure to ionizing radiation and could be used for the surveillance of lymphoma. The current role of whole-body MRI in the diagnostic workup in lymphoma is examined in the present review along with the diagnostic performance in staging, response assessment and surveillance of different lymphoma subtypes.

Repeatability and reproducibility of ADC measurements: a prospective multicenter whole-body-MRI study

OBJECTIVES

Multicenter oncology trials increasingly include MRI examinations with apparent diffusion coefficient (ADC) quantification for lesion characterization and follow-up. However, the repeatability and reproducibility (R&R) limits above which a true change in ADC can be considered relevant are poorly defined. This study assessed these limits in a standardized whole-body (WB)-MRI protocol.

METHODS

A prospective, multicenter study was performed at three centers equipped with the same 3.0-T scanners to test a WB-MRI protocol including diffusion-weighted imaging (DWI). Eight healthy volunteers per center were enrolled to undergo test and retest examinations in the same center and a third examination in another center. ADC variability was assessed in multiple organs by two readers using two-way mixed ANOVA, Bland-Altman plots, coefficient of variation (CoV), and the upper limit of the 95% CI on repeatability (RC) and reproducibility (RDC) coefficients.

RESULTS

CoV of ADC was not influenced by other factors (center, reader) than the organ. Based on the upper limit of the 95% CI on RC and RDC (from both readers), a change in ADC in an individual patient must be superior to 12% (cerebrum white matter), 16% (paraspinal muscle), 22% (renal cortex), 26% (central and peripheral zones of the prostate), 29% (renal medulla), 35% (liver), 45% (spleen), 50% (posterior iliac crest), 66% (L5 vertebra), 68% (femur), and 94% (acetabulum) to be significant.

CONCLUSIONS

This study proposes R&R limits above which ADC changes can be considered as a reliable quantitative endpoint to assess disease or treatment-related changes in the tissue microstructure in the setting of multicenter WB-MRI trials.

KEY POINTS

• The present study showed the range of R&R of ADC in WB-MRI that may be achieved in a multicenter framework when a standardized protocol is deployed. • R&R was not influenced by the site of acquisition of DW images. • Clinically significant changes in ADC measured in a multicenter WB-MRI protocol performed with the same type of MRI scanner must be superior to 12% (cerebrum white matter), 16% (paraspinal muscle), 22% (renal cortex), 26% (central zone and peripheral zone of prostate), 29% (renal medulla), 35% (liver), 45% (spleen), 50% (posterior iliac crest), 66% (L5 vertebra), 68% (femur), and 94% (acetabulum) to be detected with a 95% confidence level.

Whole-body magnetic resonance imaging in children - how and why? A systematic review

Whole-body magnetic resonance imaging (MRI) is increasingly being used for a number of indications. Our aim was to review and describe indications and scan protocols for diagnostic value of whole-body MRI for multifocal disease in children and adolescents, we conducted a systematic search in Medline, Embase and Cochrane for all published papers until November 2018. Relevant subject headings and free text words were used for the following concepts: 1) whole-body, 2) magnetic resonance imaging and 3) child and/or adolescent. Included were papers in English with a relevant study design that reported on the use and/or findings from whole-body MRI examinations in children and adolescents. This review includes 54 of 1,609 papers identified from literature searches. Chronic nonbacterial osteomyelitis, lymphoma and metastasis were the most frequent indications for performing a whole-body MRI. The typical protocol included a coronal STIR (short tau inversion recovery) sequence with or without a coronal T1-weighted sequence. Numerous studies lacked sufficient data for calculating images resolution and only a few studies reported the acquired voxel volume, making it impossible for others to reproduce the protocol/images. Only a minority of the included papers assessed reliability tests and none of the studies documented whether the use of whole-body MRI affected mortality and/or morbidity. Our systematic review confirms significant variability of technique and the lack of proven validity of MRI findings. The information could potentially be used to boost attempts towards standardization of technique, reporting and guidelines development.

Whole Body 3.0 T Magnetic Resonance Imaging in Lymphomas: Comparison of Different Sequence Combinations for Staging Hodgkin's and Diffuse Large B Cell Lymphomas

To investigate the diagnostic value of different whole-body magnetic resonance imaging (WB-MRI) protocols for staging Hodgkin and diffuse-large B-cell lymphomas (HL and DLBCL), twenty-two patients (M/F 12/10, median age 32, range 22-87, HL/DLBCL 14/8) underwent baseline WB-MRI and 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET) fused with computed tomography (CT) scan 18F-FDG-PET-CT. The 3.0 T WB-MRI was performed using pre-contrast modified Dixon (mDixon), T2-weighted turbo-spin-echo (TSE), diffusion-weighted-imaging (DWI), dynamic-contrast-enhanced (DCE) liver/spleen, contrast-enhanced (CE) lung MRI and CE whole-body mDixon. WB-MRI scans were divided into: (1) "WB-MRI DWI+IP": whole-body DWI + in-phase mDixon (2) "WB-MRI T2-TSE": whole-body T2-TSE (3) "WB-MRI Post-C": whole-body CE mDixon + DCE liver/spleen and CE lung mDixon (4) "WB-MRI All ": the entire protocol. Two radiologists evaluated WB-MRIs at random, independently and then in consensus. Two nuclear-medicine-physicians reviewed 18F-FDG PET-CT in consensus. An enhanced-reference-standard (ERS) was derived using all available baseline and follow-up imaging. The sensitivity and specificity of WB-MRI protocols for nodal and extra-nodal staging was derived against the ERS. Agreement between the WB-MRI protocols and the ERS for overall staging was assessed using kappa statistic. For consensus WB-MRI, the sensitivity and specificity for nodal staging were 75%, 98% for WB-MRI DWI+IP, 76%, 98% for WB-MRI Post-C, 83%, 99% for WB-MRI T2-TSE and 87%, 100% for WB-MRI All. The sensitivity and specificity for extra-nodal staging were 67% 100% for WB-MRI DWI+IP, 89%, 100% for WB-MRI Post-C, 89%, 100% for WB-MRI T2-TSE and 100%, 100% for the WB-MRI All. The consensus WB-MRI All read had perfect agreement with the ERS for overall staging [kappa = 1.00 (95% CI: 1.00-1.00)]. The best diagnostic performance is achieved combining all available WB-MRI sequences.

Detection and Characterization of Musculoskeletal Cancer Using Whole-Body Magnetic Resonance Imaging

Whole-body magnetic resonance imaging (WB-MRI) is gradually being integrated into clinical pathways for the detection, characterization, and staging of malignant tumors including those arising in the musculoskeletal (MSK) system. Although further developments and research are needed, it is now recognized that WB-MRI enables reliable, sensitive, and specific detection and quantification of disease burden, with clinical applications for a variety of disease types and a particular application for skeletal involvement. Advances in imaging techniques now allow the reliable incorporation of WB-MRI into clinical pathways, and guidelines recommending its use are emerging. This review assesses the benefits, clinical applications, limitations, and future capabilities of WB-MRI in the context of other next-generation imaging modalities, as a qualitative and quantitative tool for the detection and characterization of skeletal and soft tissue MSK malignancies.

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

Objectives

To assess the concordance of whole-body MRI (WB-MRI) and an FDG-PET/CT-based reference standard for the initial staging in children with Hodgkin lymphoma (HL)

Methods

Children with newly diagnosed HL were included in this prospective, multicentre, international study and underwent WB-MRI and FDG-PET/CT at staging. Two radiologists and a nuclear medicine physician independently evaluated all images. Discrepancies between WB-MRI and FDG-PET/CT were assessed by an expert panel. All FDG-PET/CT errors were corrected to derive the FDG-PET/CT-based reference standard. The expert panel corrected all reader errors in the WB-MRI DWI dataset to form the intrinsic MRI data. Inter-observer agreement for WB-MRI DWI was calculated using overall agreement, specific agreements and kappa statistics. Concordance for correct classification of all disease sites and disease stage between WB-MRI (without DWI, with DWI and intrinsic WB-MRI DWI) and the reference standard was calculated as primary outcome. Secondary outcomes included positive predictive value, negative predictive value and kappa statistics. Clustering within patients was accounted for using a mixed-effect logistic regression model with random intercepts and a multilevel kappa analysis.

Results

Sixty-eight children were included. Inter-observer agreement between WB-MRI DWI readers was good for disease stage (κ = 0.74). WB-MRI DWI agreed with the FDG-PET/CT-based reference standard for determining disease stage in 96% of the patients versus 88% for WB-MRI without DWI. Agreement between WB-MRI DWI and the reference standard was excellent for both nodal (98%) and extra-nodal (100%) staging.

Conclusions

WB-MRI DWI showed excellent agreement with the FDG-PET/CT-based reference standard. The addition of DWI to the WB-MRI protocol improved the staging agreement.

Key Points

• This study showed excellent agreement between WB-MRI DWI and an FDG-PET/CT-based reference standard for staging paediatric HL.

• Diffusion-weighted imaging is a useful addition to WB-MRI in staging paediatric HL.

• Inter-observer agreement for WB-MRI DWI was good for both nodal and extra-nodal staging and determining disease stage.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07182-0) contains supplementary material, which is available to authorized users.

Relevance on the diagnosis of malignant lymphoma of the salivary gland

Malignant lymphoma originates from the lymphohematopoietic system. It can occur in any lymphoid tissue. Malignant lymphoma of the salivary gland is rare, but its incidence has increased in recent years. Its clinical- presentations are non-specific, and it is often manifested as a painless mass in a salivary gland, which can be accompanied by multiple swollen cervical lymph nodes. Confirmation of the diagnosis before an invasive procedure is difficult. Clinically, malignant lymphoma of the salivary gland tends to be misdiagnosed, leading to an inappropriate treatment plan and the ultimate delay in the optimal treatment of the disease. This article reviews the pathogenesis, clinical features, imaging findings, diagnosis, treatment and prognosis of malignant lymphoma of the salivary gland.

Therapy Response Assessment of Pediatric Tumors with Whole-Body Diffusion-weighted MRI and FDG PET/MRI

Background Whole-body diffusion-weighted (DW) MRI can help detect cancer with high sensitivity. However, the assessment of therapy response often requires information about tumor metabolism, which is measured with fluorine 18 fluorodeoxyglucose (FDG) PET. Purpose To compare tumor therapy response with whole-body DW MRI and FDG PET/MRI in children and young adults. Materials and Methods In this prospective, nonrandomized multicenter study, 56 children and young adults (31 male and 25 female participants; mean age, 15 years ± 4 [standard deviation]; age range, 6-22 years) with lymphoma or sarcoma underwent 112 simultaneous whole-body DW MRI and FDG PET/MRI between June 2015 and December 2018 before and after induction chemotherapy (ClinicalTrials.gov identifier: NCT01542879). The authors measured minimum tumor apparent diffusion coefficients (ADCs) and maximum standardized uptake value (SUV) of up to six target lesions and assessed therapy response after induction chemotherapy according to the Lugano classification or PET Response Criteria in Solid Tumors. The authors evaluated agreements between whole-body DW MRI- and FDG PET/MRI-based response classifications with Krippendorff α statistics. Differences in minimum ADC and maximum SUV between responders and nonresponders and comparison of timing for discordant and concordant response assessments after induction chemotherapy were evaluated with the Wilcoxon test. Results Good agreement existed between treatment response assessments after induction chemotherapy with whole-body DW MRI and FDG PET/MRI (α = 0.88). Clinical response prediction according to maximum SUV (area under the receiver operating characteristic curve = 100%; 95% confidence interval [CI]: 99%, 100%) and minimum ADC (area under the receiver operating characteristic curve = 98%; 95% CI: 94%, 100%) were similar (P = .37). Sensitivity and specificity were 96% (54 of 56 participants; 95% CI: 86%, 99%) and 100% (56 of 56 participants; 95% CI: 54%, 100%), respectively, for DW MRI and 100% (56 of 56 participants; 95% CI: 93%, 100%) and 100% (56 of 56 participants; 95% CI: 54%, 100%) for FDG PET/MRI. In eight of 56 patients who underwent imaging after induction chemotherapy in the early posttreatment phase, chemotherapy-induced changes in tumor metabolism preceded changes in proton diffusion (P = .002). Conclusion Whole-body diffusion-weighted MRI showed significant agreement with fluorine 18 fluorodeoxyglucose PET/MRI for treatment response assessment in children and young adults. © RSNA, 2020 Online supplemental material is available for this article.

Whole-body magnetic resonance imaging (WB-MRI) in oncology: an Italian survey

PURPOSE

To perform a survey among all members of the Italian Society of Medical and Interventional Radiology (SIRM) to assess how whole-body MRI (WB-MRI) is performed in oncologic patients in Italy.

METHODS

On March 2019, we administered an online poll to all SIRM members about their use of WB-MRI in 2018 asking 15 questions regarding oncologic indications, imaging protocol, use of contrast media, experience in WB-MRI, duration of scan time and reporting time.

RESULTS

Forty-eight members participated to the survey. WB-MRIs/total MRIs ratio was 1%. Lymphoma was the most common indication (17/48, 35%), followed by myeloma and prostate cancer, with these three tumors representing the most common indication in 39/48 of cases (81%). WB-MRI acquisition time and reporting time were 46-60 min in 22/48 centers (46%) and 20-30 min in 19/48 (40%), respectively. WB-MRIs were mostly performed in 1.5T scanners (43/48, 90%), with surface coils (22/48, 46%) being preferred to Q-body (15/48, 31%) and integrated coils (11/48, 23%). Contrast media were injected in 22/48 of the centers (46%), mainly used for breast cancer (13/22, 59%). DWI was the most used sequence (45/48, 94%), mostly with b800 (27/48, 56%), b0 (24/48, 50%) and b1000 (20/48, 42%) values. In about half of cases, radiologists started evaluating WB-MRI non-contrast morphologic sequences, then checking DWI and post-contrast images.

CONCLUSION

WB-MRI was mainly performed at 1.5T unit, with lymphoma, myeloma and prostate cancer having been the most common indications. The extreme variability in the choice of imaging protocols and use of contrast agents demonstrates the need of a standardization of WB-MRI application in clinical practice.

Comparison of whole-body MRI with diffusion-weighted imaging and PET/CT in lymphoma staging

OBJECTIVES

To compare the diagnostic efficiency of whole-body MRI-DWI and PET/CT in lymphoma staging.

METHODS

A prospective study enrolled 92 patients with lymphoma. Prior to treatment, all patients underwent whole-body MRI-DWI and PET-CT. The methods' efficiency was compared in the diagnosis of lymph node (LN) and organ involvement, and in determining lymphoma stage.

RESULTS

Sensitivity, specificity, and accuracy in the diagnosis of enlarged LN involvement were 98.2%, 99.9%, and 99.3%, respectively, for MRI-DWI, and 99.4%, 100.0%, and 99.8%, respectively, for PET/CT. ROC analysis showed similar methods' efficiency in the diagnosis of enlarged LN involvement (p > 0.06). MRI-DWI and PET/CT sensitivity in the diagnosis of non-enlarged LN involvement was 77.8% and 88.1%, respectively (p < 0.001). MRI-DWI and PET/CT sensitivity, specificity, and accuracy in the diagnosis of lung involvement were 73.3%, 98.7%, 94.6% and 86.7%, 98.7%, 96.7%; spleen involvement 54.8%, 98.3%, 83.3% and 100.0%, 100.0%, 100.0%; bone marrow involvement 87.1%, 96.4%, 93.0% and 64.5%, 87.3%, 79.1%; and all-organ involvement 72.9%, 98.1%, 91.4% and 80.0%, 96.6%, 92.2%, respectively. ROC analysis showed similar methods' efficiency in the diagnosis of lung involvement (р > 0.3), higher for PET/CT in spleen involvement (р < 0.0001), higher for MRI-DWI in bone marrow involvement (р < 0.0008), and similar in all-organ involvement (р > 0.35). MRI-DWI and PET/CT determined the correct lymphoma stage in 79 (86%) patients.

CONCLUSIONS

Whole-body MRI-DWI and PET/CT determined the correct lymphoma stage in similar numbers of patients. MRI-DWI can serve as a non-irradiative alternative to PET/CT in lymphoma staging.

KEY POINTS

• Whole-body MRI-DWI efficiency compared with that of PET/CT is similar in the diagnosis of enlarged LN involvement, inferior in the diagnosis of non-enlarged LN and spleen involvement, but superior in the diagnosis of bone marrow involvement. • A new efficient MRI-DWI sign for diagnosis of diffuse bone marrow involvement has been proposed, i.e., a diffuse increase in spine signal intensity on high b value DWI images above the kidney parenchyma. • MRI-DWI and PET/CT determined the correct lymphoma stage in similar numbers of patients.

Whole-Body Diffusion-Weighted MRI Compared to 18 FFDG PET/CT in Initial Staging and Therapy Response Assessment of Hodgkin Lymphoma in Pediatric Patients

PURPOSE

The aim of our study was to compare whole-body diffusion-weighted MRI (WB-DWI-MRI) to fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the assessment of initial staging and treatment response in pediatric patients with Hodgkin lymphoma.

MATERIALS AND METHODS

This prospective study comprised 11 children with Hodgkin lymphoma. Whole-body DWI-MRI and FDG-PET/CT were obtained at baseline and after 2 cycles of chemotherapy. Two radiologists measured the apparent diffusion coefficient (ADC) values of the sites of involvement agreed upon in consensus and 1 nuclear medicine physician assessed the PET/CT. Reliability of radiologists' ratings was assessed by intraclass correlation coefficients (ICC_2,1). The sensitivity and positive predictive value (PPV) of DW-MRI relative to PET/CT were calculated for nodal and extranodal sites. The patients were staged according to both modalities. Association of treatment responses was assessed through the Pearson correlation between the ADC ratios and the change standardized uptake value (SUV) between baseline and follow-up.

RESULTS

There was good agreement between the raters for nodal and extranodal ADC measurements. The sensitivity and PPV of DW-MRI relative to PET/CT of nodal disease was 0.651 and 1.0, respectively, at baseline, and 0.697 and 0.885 at follow-up. The sensitivity and PPV of extranodal disease were 0.545 and 0.6 at baseline, and 0.167 and 0.333 at follow-up. Diffusion-weighted MRI determined correct tumor stage in 8 of 11 examinations. There was poor correlation between the ADC ratios and the absolute change in SUV between baseline and follow-up (0.348).

CONCLUSION

Our experience showed that WB-DWI-MRI is inferior to PET/CT for initial staging and assessment of treatment response of Hodgkin lymphoma in pediatric patients.

Whole-body magnetic resonance imaging in pediatric oncology - recommendations by the Oncology Task Force of the ESPR

The purpose of this recommendation of the Oncology Task Force of the European Society of Paediatric Radiology (ESPR) is to indicate reasonable applications of whole-body MRI in children with cancer and to address useful protocols to optimize workflow and diagnostic performance. Whole-body MRI as a radiation-free modality has been increasingly performed over the last two decades, and newer applications, as in screening of children with germ-line mutation cancer-related gene defects, are now widely accepted. We aim to provide a comprehensive outline of the diagnostic value for use in daily practice. Based on the results of our task force session in 2018 and the revision in 2019 during the ESPR meeting, we summarized our group's experiences in whole-body MRI. The lack of large evidence by clinical studies is challenging when focusing on a balanced view regarding the impact of whole-body MRI in pediatric oncology. Therefore, the final version of this recommendation was supported by the members of Oncology Task Force.

Localising occult prostate cancer metastasis with advanced imaging techniques (LOCATE trial): a prospective cohort, observational diagnostic accuracy trial investigating whole-body magnetic resonance imaging in radio-recurrent prostate cancer

BACKGROUND

Accurate whole-body staging following biochemical relapse in prostate cancer is vital in determining the optimum disease management. Current imaging guidelines recommend various imaging platforms such as computed tomography (CT), Technetium 99 m (99mTc) bone scan and 18F-choline and recently 68Ga-PSMA positron emission tomography (PET) for the evaluation of the extent of disease. Such approach requires multiple hospital attendances and can be time and resource intensive. Recently, whole-body magnetic resonance imaging (WB-MRI) has been used in a single visit scanning session for several malignancies, including prostate cancer, with promising results, providing similar accuracy compared to the combined conventional imaging techniques. The LOCATE trial aims to investigate the application of WB-MRI for re-staging of patients with biochemical relapse (BCR) following external beam radiotherapy and brachytherapy in patients with prostate cancer.

METHODS/DESIGN

The LOCATE trial is a prospective cohort, multi-centre, non-randomised, diagnostic accuracy study comparing WB-MRI and conventional imaging. Eligible patients will undergo WB-MRI in addition to conventional imaging investigations at the time of BCR and will be asked to attend a second WB-MRI exam, 12-months following the initial scan. WB-MRI results will be compared to an enhanced reference standard comprising all the initial, follow-up imaging and non-imaging investigations. The diagnostic performance (sensitivity and specificity analysis) of WB-MRI for re-staging of BCR will be investigated against the enhanced reference standard on a per-patient basis. An economic analysis of WB-MRI compared to conventional imaging pathways will be performed to inform the cost-effectiveness of the WB-MRI imaging pathway. Additionally, an exploratory sub-study will be performed on blood samples and exosome-derived human epidermal growth factor receptor (HER) dimer measurements will be taken to investigate its significance in this cohort.

DISCUSSION

The LOCATE trial will compare WB-MRI versus the conventional imaging pathway including its cost-effectiveness, therefore informing the most accurate and efficient imaging pathway.

TRIAL REGISTRATION

LOCATE trial was registered on ClinicalTrial.gov on 18th of October 2016 with registration reference number NCT02935816.