Pitfalls in whole body MRI with diffusion weighted imaging performed on patients with lymphoma: What radiologists should know

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.

Optimized Whole-Body PET MRI Sequence Workflow in Pediatric Hodgkin Lymphoma Patients

¹⁸F-FDG PET/MRI might be the diagnostic method of choice for Hodgkin lymphoma patients, as it combines significant metabolic information from PET with excellent soft-tissue contrast from MRI and avoids radiation exposure from CT. However, a major issue is longer examination times than for PET/CT, especially for younger children needing anesthesia. Thus, a targeted selection of suitable whole-body MRI sequences is important to optimize the PET/MRI workflow. Methods: The initial PET/MRI scans of 84 EuroNet-PHL-C2 study patients from 13 international PET centers were evaluated. In each available MRI sequence, 5 PET-positive lymph nodes were assessed. If extranodal involvement occurred, 2 splenic lesions, 2 skeletal lesions, and 2 lung lesions were also assessed. A detection rate was calculated dividing the number of visible, anatomically assignable, and measurable lesions in the respective MRI sequence by the total number of lesions. Results: Relaxation time-weighted (T2w) transverse sequences with fat saturation (fs) yielded the best result, with detection rates of 95% for nodal lesions, 62% for splenic lesions, 94% for skeletal lesions, and 83% for lung lesions, followed by T2w transverse sequences without fs (86%, 49%, 16%, and 59%, respectively) and longitudinal relaxation time-weighted contrast-enhanced transverse sequences with fs (74%, 35%, 57%, and 55%, respectively). Conclusion: T2w transverse sequences with fs yielded the highest detection rates and are well suited for accurate whole-body PET/MRI in lymphoma patients. There is no evidence to recommend the use of contrast agents.

[Imaging for Multiple Myeloma according to the Recent International Myeloma Working Group Guidelines: Analysis of Image Acquisition Techniques and Response Evaluation in Whole-Body MRI according to MY-RADS]

Multiple myeloma (MM) is a malignant hematologic disease caused by the proliferation of clonal plasma cells in the bone marrow, and its incidence is increasing in Korea. With the development of treatments for MM, the need for early diagnosis and treatment has emerged. In recent years, the International Myeloma Working Group (IMWG) has been constantly revising the laboratory and radiological diagnostic criteria for MM. In addition, as whole-body MRI (WBMR) has been increasing used in the diagnosis and treatment response evaluation of patients with MM, the Myeloma Response Assessment and Diagnosis System (MY-RADS) was created to standardize WBMR image acquisition techniques, image interpretation, and response evaluation methods. Radiologists need to have a detailed knowledge of the features of MM for accurate diagnosis. Thus, in this review article, we describe the imaging method for MM according to the latest IMWG guidelines as well as the image acquisition and response evaluation technique for WBMR according to MY-RADS.

Giant subcutaneous bronchogenic cyst in the intergluteal cleft region of an adult: a case report and literature review

BACKGROUND

Bronchogenic cysts (BCs) are generally detected in the mediastinum, along the tracheobronchial tree, or in the lung parenchyma. Subcutaneous BCs are rare, but, when found, are usually small (< 3 cm) and detected in children.

CASE PRESENTATION

In an unusual adult case, we treated a 52-year-old woman who presented with a mass in the left intergluteal cleft region. Ultrasonography showed a well-circumscribed hypoechoic lesion with posterior enhancement and internal echogenic foci within the mass. Color Doppler images showed no signals. Computed tomography showed the mass as a homogeneous, 6.8- × 6.3- × 5.1-cm soft tissue-attenuation lesion lodged in subcutaneous fatty tissue. Magnetic resonance imaging revealed a cystic lesion of similar dimensions with heterogeneous hyperintensity on both T1- and T2-weighted images. No contrast enhancement, solid components, or restricted diffusion foci were apparent. The cyst was completely excised, and histopathological evaluation indicated it was a BC. The patient's recovery was uneventful.

CONCLUSIONS

BCs should be considered in the differential diagnosis of all subcutaneous cystic masses, regardless of their location and size and the patient's age.

Diagnostic performance of computed tomography and diffusion-weighted imaging as first-line imaging modality according to the International Myeloma Working Group (IMWG) imaging algorithm for monoclonal plasma cell disorders

BACKGROUND

The latest International Myeloma Working Group (IMWG) guideline recommends low-dose whole-body (WB) computed tomography (CT) as the first-line imaging technique for the initial diagnosis of plasma cell disorders.

PURPOSE

To evaluate diagnostic performances of CT and diffusion-weighted imaging (DWI) as the first-line imaging modalities and assess misclassification rates obtained following the guideline.

MATERIAL AND METHODS

Two independent radiologists analyzed CT (acquired as PET/CT) and DWI (3-T; b-values = 50 and 900 s/mm²) of patients newly diagnosed with plasma cell disorder, categorizing the number of bone lesions. Diagnostic performance of CT and DWI was compared using the McNemar test, and misclassification rates were calculated with a consensus WB-MRI reading as the reference standard. Differences in lesion number categories were assessed using marginal homogeneity and kappa statistics.

RESULTS

Of 56 patients (36 men; mean age = 63.5 years), 39 had myeloma lesions. DWI showed slightly higher sensitivity for detecting myeloma lesions (97.4%) than CT (84.6%-92.3%; P > 0.05). CT showed significantly higher specificity (88.2%) than DWI (52.9%-58.8%; P<0.05). CT had a higher additional study requirement rate than DWI (7.7%-15.4% vs. 2.6%), but a lower unnecessary treatment rate (11.8% vs. 41.2%-47.1%). Both readers showed significant differences in categorization of the number of lesions on CT compared with the reference standard (P < 0.001), and one reader showed a significant difference on DWI (P = 0.006 and 0.098).

CONCLUSION

CT interpreted according to the IMWG guideline is a diagnostically effective first-line modality with relatively high sensitivity and specificity. DWI alone may not be an acceptable first-line imaging modality because of low specificity.

Whole-body MRI: detecting bone metastases from prostate cancer

Whole-body magnetic resonance imaging (WB-MRI) is currently used worldwide for detecting bone metastases from prostate cancer. The 5-year survival rate for prostate cancer is > 95%. However, an increase in survival time may increase the incidence of bone metastasis. Therefore, detecting bone metastases is of great clinical interest. Bone metastases are commonly located in the spine, pelvis, shoulder, and distal femur. Bone metastases from prostate cancer are well-known representatives of osteoblastic metastases. However, other types of bone metastases, such as mixed or inter-trabecular type, have also been detected using MRI. MRI does not involve radiation exposure and has good sensitivity and specificity for detecting bone metastases. WB-MRI has undergone gradual developments since the last century, and in 2004, Takahara et al., developed diffusion-weighted Imaging (DWI) with background body signal suppression (DWIBS). Since then, WB-MRI, including DWI, has continued to play an important role in detecting bone metastases and monitoring therapeutic effects. An imaging protocol that allows complete examination within approximately 30 min has been established. This review focuses on WB-MRI standardization and the automatic calculation of tumor total diffusion volume (tDV) and mean apparent diffusion coefficient (ADC) value. In the future, artificial intelligence (AI) will enable shorter imaging times and easier automatic segmentation.

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.

Pediatric skeletal diffusion-weighted magnetic resonance imaging: part 1 - technical considerations and optimization strategies

Diffusion-weighted MRI, or DWI, is a fast, quantitative technique that is easily integrated into a morphological MR acquisition. The ability of DWI to aid in detecting multifocal skeletal pathology and in characterizing tissue cellularity to a level beyond that possible with other techniques makes it a niche component of multiparametric MR imaging of the skeleton. Besides its role in disease detection and establishing cellularity and character of osseous lesions, DWI continues to be examined as a surrogate biomarker for therapeutic response of several childhood bone tumors. There is increasing interest in harnessing DWI as a potential substitute to alternative modes of imaging evaluation that involve radiation or administration of intravenous contrast agent or radiopharmaceuticals, for example in early detection and diagnosis of capital femoral epiphyseal ischemia in cases of Legg-Calvé-Perthes disease, or diagnosis and staging of lymphoma. The expected evolution of skeletal diffusivity characteristics with maturation and the unique disease processes that affect the pediatric skeleton necessitate a pediatric-specific discussion. In this article, the author examines the developmentally appropriate normal appearances, technique, artifacts and pitfalls of pediatric skeletal DWI.

Imaging side effects and complications of chemotherapy and radiation therapy: a pictorial review from head to toe

Newer biologic drugs and immunomodulatory agents, as well as more tolerated and effective radiation therapy schemes, have reduced treatment toxicity in oncology patients. However, although imaging assessment of tumor response is adapting to atypical responses like tumor flare, expected changes and complications of chemo/radiotherapy are still routinely encountered in post-treatment imaging examinations. Radiologists must be aware of old and newer therapeutic options and related side effects or complications to avoid a misinterpretation of imaging findings. Further, advancements in oncology research have increased life expectancy of patients as well as the frequency of long-term therapy-related side effects that once could not be observed. This pictorial will help radiologists tasked to detect therapy-related complications and to differentiate expected changes of normal tissues from tumor relapse.

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.

Diagnostic accuracy of pelvic magnetic resonance imaging for the assessment of bone marrow involvement in diffuse large B-cell lymphoma

Purpose

We investigated the efficacy of pelvic magnetic resonance imaging (MRI) in the diagnosis of bone marrow involvement (BMinv) in diffuse large B-cell lymphoma (DLBCL) patients.

Patients and methods

This was a retrospective study of data from a previous study (NCT02733887). We included 171 patients who underwent bone marrow biopsy (BMB) and bone marrow smear (BMS), pelvic MRI, and whole-body positron emission tomography-computed tomography (PET/CT) from January 2016 to December 2019 at a single center. BMB/BMS and whole-body PET/CT results were used as reference standards against which we calculated the diagnostic value of pelvic MRI for BMinv in DLBCL patients. A chi-square test was used to compare detection rates, and a receiver operating characteristic curve was used to evaluate diagnostic value of pelvic MRI. Propensity-score matching was performed according to clinical information, and Kaplan-Meier curves were constructed to compare progression-free survival (PFS) and overall survival (OS) of patients.

Results

The BMinv detection rate of pelvic MRI (42/171) was higher (P = 0.029) than that of BMB/BMS (25/171), and similar to that of PET/CT (44/171; P = 0.901). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of pelvic MRI were 83.33%, 98.37%, 94.15%, 95.24%, and 93.80%, respectively. Median PFS values were as follows: BMB/BMS-positive, 17.8 months vs. BMB/BMS-negative, 26.9 months (P = 0.092); PET/CT-positive, 24.8 months vs. PET/CT-negative, 33.0 months (P = 0.086); pelvic MRI-positive, 24.9 months vs. pelvic MRI-negative, 33.1 months (P<0.001). Median OS values were as follows: BMB/BMS-positive, 22.3 months vs. BMB/BMS-negative, 29.8 months (P = 0.240); PET/CT-positive, 27.9 months vs. PET/CT-negative, 33.9 months (P = 0.365); pelvic MRI-positive, 27.3 months vs. pelvic MRI-negative, 35.8 months (P = 0.062).

Conclusion

Pelvic MRI is effective for detecting BMinv in DLBCL patients, providing a more accurate indication of PFS than BMB/BMS and PET/CT do. It may ultimately be used to improve the accuracy of clinical staging, guide patient treatment, and evaluate prognosis.

Oncologically Relevant Findings Reporting and Data System (ONCO-RADS): Guidelines for the Acquisition, Interpretation, and Reporting of Whole-Body MRI for Cancer Screening

Acknowledging the increasing number of studies describing the use of whole-body MRI for cancer screening, and the increasing number of examinations being performed in patients with known cancers, an international multidisciplinary expert panel of radiologists and a geneticist with subject-specific expertise formulated technical acquisition standards, interpretation criteria, and limitations of whole-body MRI for cancer screening in individuals at higher risk, including those with cancer predisposition syndromes. The Oncologically Relevant Findings Reporting and Data System (ONCO-RADS) proposes a standard protocol for individuals at higher risk, including those with cancer predisposition syndromes. ONCO-RADS emphasizes structured reporting and five assessment categories for the classification of whole-body MRI findings. The ONCO-RADS guidelines are designed to promote standardization and limit variations in the acquisition, interpretation, and reporting of whole-body MRI scans for cancer screening. Published under a CC BY 4.0 license Online supplemental material is available for this article.

Assessment of naive indolent lymphoma using whole-body diffusion-weighted imaging and T2-weighted MRI: results of a prospective study in 30 patients

Background

We prospectively evaluated the diagnostic utility of whole-body diffusion-weighted imaging with background body signal suppression and T2-weighted short-tau inversion recovery MRI (WB-DWIBS/STIR) for the pretherapeutic staging of indolent lymphoma in 30 patients.

Methods

This prospective study included 30 treatment-naive patients with indolent lymphomas who underwent WB-DWIBS/STIR and conventional imaging workup plus biopsy. The pretherapeutic staging agreement, sensitivity, and specificity of WB-DWIBS/STIR were investigated with reference to the multimodality and multidisciplinary consensus review for nodal and extranodal lesions excluding bone marrow.

Results

In the pretherapeutic staging, WB-DWIBS/STIR showed very good agreement (κ = 0.96; confidence interval [CI], 0.88–1.00), high sensitivity (93.4–95.1%), and high specificity (99.0–99.4%) for the whole-body regions. These results were similar to those of ¹⁸F-FDG-PET/CT, except for the sensitivity for extranodal lesions. For extranodal lesions, WB-DWIBS/STIR showed higher sensitivity compared to ¹⁸F-FDG-PET/CT for the whole-body regions (94.9–96.8% vs. 79.6–86.3%, P = 0.058).

Conclusion

WB-DWIBS/STIR is an effective modality for the pretherapeutic staging of indolent lymphoma, and it has benefits when evaluating extranodal lesions, compared with ¹⁸F-FDG-PET/CT.

[Diagnostic imaging of malignant lymphomas]

BACKROUND

Malignant lymphomas represent approximately 5% of all cancers. Imaging procedures play a crucial role concerning initial staging and assessment of the response to treatment.

OBJECTIVE

This article gives an overview of the significance of imaging procedures in the treatment of patients with malignant lymphomas at various times during treatment. These include the initial assessment of the extent of the disease and staging during and after treatment under consideration of the current classification systems.

MATERIAL AND METHODS

A selective literature search was carried out with analysis of dedicated original research articles and reviews as well as a discussion of the clinical guidelines.

RESULTS

Computed tomography (CT) is the basic diagnostic tool in patients with malignant lymphomas. Particularly important is fluorodeoxyglucose (FDG) positron emission tomography (PET) CT, which enables a more accurate stage definition and a better assessment of the response to treatment in FDG-avid lymphoma subtypes. Using the FDG-PET/CT-based Deauville score persisting disease activity can be identified in residual masses and refractory disease can be distinguished from complete metabolic remission. The use of magnetic resonance imaging (MRI) with diffusion-weighted imaging can represent a future alternative but is, however, not yet sufficiently standardized and validated.

CONCLUSION

The standardized analysis and reporting of purely morphological and metabolic imaging procedures is the backbone of treatment decisions in patients with malignant lymphomas.

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.

Diffusion-Weighted Imaging in Oncology: An Update

To date, diffusion weighted imaging (DWI) is included in routine magnetic resonance imaging (MRI) protocols for several cancers. The real additive role of DWI lies in the "functional" information obtained by probing the free diffusivity of water molecules into intra and inter-cellular spaces that in tumors mainly depend on cellularity. Although DWI has not gained much space in some oncologic scenarios, this non-invasive tool is routinely used in clinical practice and still remains a hot research topic: it has been tested in almost all cancers to differentiate malignant from benign lesions, to distinguish different malignant histotypes or tumor grades, to predict and/or assess treatment responses, and to identify residual or recurrent tumors in follow-up examinations. In this review, we provide an up-to-date overview on the application of DWI in oncology.

Theragnostic Use of Radiolabelled Dota-Peptides in Meningioma: From Clinical Demand to Future Applications

Meningiomas account for approximately 30% of all new diagnoses of intracranial masses. The 2016 World Health Organization's (WHO) classification currently represents the clinical standard for meningioma's grading and prognostic stratification. However, watchful waiting is frequently the chosen treatment option, although this means the absence of a certain histological diagnosis. Consequently, MRI (or less frequently CT) brain imaging currently represents the unique available tool to define diagnosis, grading, and treatment planning in many cases. Nonetheless, these neuroimaging modalities show some limitations, particularly in the evaluation of skull base lesions. The emerging evidence supporting the use of radiolabelled somatostatin receptor analogues (such as dota-peptides) to provide molecular imaging of meningiomas might at least partially overcome these limitations. Moreover, their potential therapeutic usage might enrich the current clinical offering for these patients. Starting from the strengths and weaknesses of structural and functional neuroimaging in meningiomas, in the present article we systematically reviewed the published studies regarding the use of radiolabelled dota-peptides in surgery and radiotherapy planning, in the restaging of treated patients, as well as in peptide-receptor radionuclide therapy of meningioma.

Renal endometriosis mimicking complicated cysts of kidney: report of two cases

Endometriosis is a common gynecologic disorder characterized by ectopic endometrial tissue growth outside the uterine cavity. Although usually occurring in pelvic organs, endometrial lesions may involve urinary tract. Renal endometriosis is extremely rare and it has only occasionally been reported in the past. We report two cases of patients with renal cystic lesions, incidentally found at imaging techniques during oncologic follow-up for gastric sarcoma and melanoma, initially misinterpreted as complicated haemorrhagic cysts and then histologically characterized as renal localizations of extragenital endometriosis.

Imaging features of adrenal masses

The widespread use of imaging examinations has increased the detection of incidental adrenal lesions, which are mostly benign and non-functioning adenomas. The differentiation of a benign from a malignant adrenal mass can be crucial especially in oncology patients since it would greatly affect treatment and prognosis. In this setting, imaging plays a key role in the detection and characterization of adrenal lesions, with several imaging tools which can be employed by radiologists. A thorough knowledge of the imaging features of adrenal masses is essential to better characterize these lesions, avoiding a misinterpretation of imaging findings, which frequently overlap between benign and malignant conditions, thus helping clinicians and surgeons in the management of patients. The purpose of this paper is to provide an overview of the main imaging features of adrenal masses and tumor-like conditions recalling the strengths and weaknesses of imaging modalities commonly used in adrenal imaging.

Advances in whole body MRI for musculoskeletal imaging: Diffusion-weighted imaging

Recent advances in imaging technology have enabled the acquisition of anatomical and functional imaging from head to toe in a reasonably short scan time. Accordingly, whole body magnetic resonance imaging (WB-MRI) and diffusion-weighted imaging (WB-DWI) have gained recent attention for the management of musculoskeletal problems such as bone tumors and rheumatologic diseases. WB-MRI is especially useful in diagnosing systemic or widespread disease requiring whole body evaluation, such as bone metastases, multiple myeloma, lymphoma, neurofibromatosis, and spondyloarthropathies. Among WB-MRI sequences, the WB-DWI technique greatly increases the value of WB-MRI in the evaluation of disease extent and characterization as well as treatment monitoring. In support of the utilization of WB-MRI and WB-DWI in orthopedic clinics for various musculoskeletal diseases, we provide an overview of the technical aspects of WB-MRI and WB-DWI and their clinical applications in musculoskeletal tumors and rheumatic diseases.

Clinical and prognostic value of 18F-FDG-PET/CT in restaging of pancreatic cancer

AIM

The aim of this retrospective multicentre study was to evaluate the clinical and prognostic effect of fluorine-18-fluorodeoxyglucose (F-FDG)-PET/computed tomography (CT) in the restaging process of pancreatic cancer (PC).

MATERIALS AND METHODS

Data from patients treated for primary PC, who underwent F-FDG-PET/CT for suspicious of disease progression, were collected. Accuracy was assessed employing conventional diagnostic procedures, multidisciplinary team case notes, further F-FDG-PET/CT scans and/or follow-up. Receiver operating characteristic curve and likelihood ratio (LR+/-) analyses were used for completion of accuracy definition. Progression-free survival (PFS) and overall survival were assessed by using Kaplan-Meier method. The Cox proportional hazards model was used to identify predictors of outcome.

RESULTS

Fifty-two patients (33 males and 19 females, with mean age of 59 years and range: 42-78 years) with PC were finally included in our study. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of F-FDG-PET were 85, 84, 90, 76, and 84%, respectively. Area under the curve was 0.84 (95% confidence intervals: 0.72-0.96; P<0.05). LR+ and LR- were 5.3 and 0.17, respectively. F-FDG-PET/CT revealed new metastatic foci in 5/52 patients (10%) and excluded suspicious lesions in 11/52 (21%). Analysis of PFS revealed F-FDG-PET/CT positivity to be associated with a worse cumulative survival rate over a 6 and 12-month period in comparison with F-FDG-PET/CT negativity (6-month PFS 95 vs. 67%, P<0.05; 12-month PFS 81 vs. 29%, P<0.05). A negative F-FDG-PET/CT result was associated with a significantly longer overall survival than a positive one (70 vs. 26% after 2 years, P<0.05). In addition, a positive F-FDG-PET/CT scan result and an maximum standardized uptake value (SUVmax) value more than 6 were significantly associated with an increased risk of disease progression (PET positivity hazard ratio=3.9, P=0.01; SUVmax>6 h=4.2, P=0.02) and death (PET positivity hazard ratio=3.5, P=0.02; SUVmax>6 h=3.7, P=0.01).

CONCLUSION

F-FDG-PET/CT showed high diagnostic accuracy for restaging process of PC, proving also its potential value in predicting clinical outcome after primary treatment.

Whole-body diffusion-weighted MR and FDG-PET/CT in Hodgkin Lymphoma: Predictive role before treatment and early assessment after two courses of ABVD

PURPOSE

To evaluate whether imaging features of pathologic lymph nodes on whole-body diffusion-weighted MR have a predictive role before treatment and may assess the response after two courses of chemotherapy in comparison to FDG-PET/CT in Hodgkin Lymphoma.

MATERIALS AND METHODS

We reviewed the whole-body MR and FDG-PET/CT performed on 41 patients with Hodgkin Lymphoma before and after two Doxorubicin-Bleomycin-Vinblastine-Dacarbazine (ABVD). Responder and non-responder lesions were identified on interim-FDG-PET/CT performed after two ABVD. We used Multivariate Generalized Estimating Equations model to assess statistical association between being-responder and baseline-Maximum Standard Uptake Value (SUV_max), baseline and interim-Apparent Diffusion Coefficient (ADC) and size, ADC and size changes during chemotherapy, site of disease, bulky, and stage.

RESULTS

10/41 (24%) patients were positive on interim-FDG-PET/CT. The interim-FDG-PET/CT positivity was associated with worse cumulative survival rate at 24 months in comparison to interim-FDG-PET/CT negativity (P < .05); 3/10 patients with positive interim-FDG-PET/CT and 1/31 with negative interim-FDG-PET/CT experienced disease progression. Baseline-SUV_max was 11.18 ± 5.58 (3.1-28.0) and baseline-ADC was 0.70 ± 0.14 × 10^-3 mm²/s (0.39-0.98). There was a significant difference between responder and non-responder lesions based on interim-ADC (1.83 ± 0.34 × 10^-3 mm²/s vs. 1.01 ± 0.27 × 10^-3 mm²/s;p <.001), interim-size (3.1 cm² vs. 9.4 cm²;p = .009), and bulky (8.2% vs. 66.7%;p = .002). There was no significant difference between responder and non-responder lesions based on baseline-SUV_max (p = .713), baseline-ADC (p = .253), ADC changes (p = .058), size changes (p = .085), site (p = .209), stage (p = .290), baseline-size (p = .064).

CONCLUSIONS

Interim-ADC is helpful for identifying non-responder lesions, while size changes are not useful. Baseline-SUV_max and ADC have no predictive role. Bulky is the most useful imaging parameter to predict suboptimal response to chemotherapy.

Whole-Body MRI: Current Applications in Oncology

OBJECTIVE

The purpose of this article is to review current image acquisition and interpretation for whole-body MRI, clinical applications, and the emerging roles in oncologic imaging, especially in the assessment of bone marrow diseases.

CONCLUSION

Whole-body MRI is an emerging technique used for early diagnosis, staging, and assessment of therapeutic response in oncology. The improved accessibility and advances in technology, including widely available sequences (Dixon and DWI), have accelerated its deployment and acceptance in clinical practice.

Whole body magnetic resonance in indolent lymphomas under watchful waiting: The time is now

ᅟ: The indolent non-Hodgkin lymphomas (i-NHLs) are characterised by 'indolent' clinical behaviour with slow growth and prolonged natural history. The watchful waiting (WW) strategy is a frequently employed treatment option in these patients. This implies a strict monitoring by imaging examinations, including 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) and CT. A major concern is radiation exposure due to regularly monitoring by conventional imaging procedures. Several studies have demonstrated the reliability of whole-body magnetic resonance imaging (WB-MRI) for lymphoma staging. WB-MRI could be useful for active surveillance in i-NHLs providing the suspect of disease progression that can be then confirmed by additional diagnostic procedures, including 18F-FDG-PET/CT. The directive 2013/59 by the European Union claims that if a radiation-free imaging technique allows obtaining the same diagnostic results, it should be invariably used. In this setting, WB-MRI may be considered a reasonable option in i-NHLs under WW, replacing imaging modalities that cause exposure to ionising radiations. This will help to reduce the cancer risk in i-NHL patients for whom chemo-/radiotherapy remain the usual treatment options following the usually long WW phase. The scientific community should raise the awareness of the risk of ionising radiations in i-NHLs and the emphasise the need for establishing the proper place of WB-MRI in lymphoma imaging.

KEY POINTS

• Watchful waiting is a reasonable option in patients with indolent non-Hodgkin lymphomas. • Imaging is crucial to monitor patients with indolent non-Hodgkin lymphomas. • CT and ¹⁸ F-FDG-PET/CT are commonly used, implying a substantial radiation exposure. • WB-MRI is highly reliable in lymphoma staging. • WB-MRI may be considered to monitor indolent non-Hodgkin lymphomas under watchful waiting.

Diffusion tensor imaging in the musculoskeletal and peripheral nerve systems: from experimental to clinical applications

Magnetic resonance imaging (MRI) is a well-established imaging modality which is used in all districts of the musculoskeletal and peripheral nerve systems. More recently, initial studies have applied multiparametric MRI to evaluate quantitatively different aspects of musculoskeletal and peripheral nerve diseases, thus providing not only images but also numbers and clinical data. Besides ¹H and ³¹P magnetic resonance spectroscopy, diffusion-weighted imaging (DWI) and blood oxygenation level-dependent imaging, diffusion tensor imaging (DTI) is a relatively new MRI-based technique relying on principles of DWI, which has traditionally been used mainly for evaluating the central nervous system to track fibre course. In the musculoskeletal and peripheral nerve systems, DTI has been mostly used in experimental settings, with still few indications in clinical practice. In this review, we describe the potential use of DTI to evaluate different musculoskeletal and peripheral nerve conditions, emphasising the translational aspects of this technique from the experimental to the clinical setting.

Solid bone tumors of the spine: Diagnostic performance of apparent diffusion coefficient measured using diffusion-weighted MRI using histology as a reference standard

PURPOSE

To assess the diagnostic performance of mean apparent diffusion coefficient (mADC) in differentiating benign from malignant bone spine tumors, using histology as a reference standard. Conventional magnetic resonance imaging (MRI) sequences have good reliability in evaluating spinal bone tumors, although some features of benign and malignant cancers may overlap, making the differential diagnosis challenging.

MATERIALS AND METHODS

In all, 116 patients (62 males, 54 females; mean age 59.5 ± 14.1) with biopsy-proven spinal bone tumors were studied. Field strength/sequences: 1.5T MR system; T₁ -weighted turbo spin-echo (repetition time / echo time [TR/TE], 500/13 msec; number of excitations [NEX], 2; slice thickness, 4 mm), T₂ -weighted turbo spin-echo (TR/TE, 4100/102 msec; NEX, 2; slice thickness, 4 mm), short tau inversion recovery (TR/TE, 4800/89 msec; NEX, 2; slice thickness, 4 mm, IT, 140 msec), axial spin-echo echo-planar diffusion-weighted imaging (DWI) (TR/TE 5200/72 msec; slice thickness 5 mm; field of view, 300; interslice gap, 1.5 mm; NEX, 6; echo-planar imaging factor, 96; no parallel imaging) with b-values of 0 and 1000 s/mm², and 3D fat-suppressed T₁ -weighted gradient-recalled-echo (TR/TE, 500/13 msec; slice thickness, 4 mm) after administration of 0.2 ml/kg body weight gadolinum-diethylenetriamine pentaacetic acid. Two readers manually drew regions of interest on the solid portion of the lesion (hyperintense on T₂ -weighted images, hypointense on T₁ -weighted images, and enhanced after gadolinium administration on fat-suppressed T₁ -weighted images) to calculate mADC. Histology was used as the reference standard. Tumors were classified into malignant primary tumors (MPT), bone metastases (BM), or benign primary tumors (BPT). Statistical tests: Nonnormality of distribution was tested with the Shapiro-Wilk test. The Kruskal-Wallis and Mann-Whitney U-test with Bonferroni correction were used. Sensitivity and specificity of the mADC values for BM, MPT, and BPT were calculated. Approximate receiver operating characteristic curves were created. Interobserver reproducibility was evaluated using the intraclass correlation coefficient (ICC).

RESULTS

The mADC values of MPT (n = 35), BM (n = 65), and BPT (n = 16) were 1.00 ± 0.32 (0.59-2.10) × 10^-3 mm² /s, 1.02 ± 0.25 (0.73-1.96) × 10^-3 mm² /s, 1.31 ± 0.36 (0.83-2.14) × 10^-3 mm² /s, respectively. The mADC was significantly different between BPT and all malignant lesions (BM+MPT) (P < 0.001), BM and BPT (P = 0.008), and MPT and BPT (P = 0.008). No difference was found between BM and MPT (P = 0.999). An mADC threshold of 0.952 × 10^-3 mm² /s yielded 81.3% sensitivity, 55.0% specificity. Accuracy was 76% (95% confidence interval [CI] = 63.9%-88.1%). Interobserver reproducibility was almost perfect (ICC = 0.916; 95% CI = 0.879-0.942).

CONCLUSION

DWI with mADC quantification is a reproducible tool to differentiate benign from malignant solid tumors with 76% accuracy. The mADC values of BPT were statistically higher than that of malignant tumors. However, the large overlap between cases may make mADC not helpful in a specific patient.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1034-1042.

Imaging features of solid renal masses

The widespread use of abdominal imaging techniques has increased the detection of solid renal masses over the past years. Imaging plays a crucial role in the management and surveillance and in determining which lesions need treatment. The "classical angiomyolipoma" is the only benign solid renal mass that can be characterized with confidence by imaging through the detection of a fat-containing lesion without calcifications. There is a large overlap of imaging features between benign and malignant renal masses that often makes difficult a correct characterization of these lesions. In this review, we discuss the imaging features of the main solid renal masses that may suggest a likely benign diagnosis.

Diffusion-weighted imaging for the cellularity assessment and matrix characterization of soft tissue tumour

PURPOSE

To evaluate whether apparent diffusion coefficient (ADC) of diffusion-weighted imaging (DWI) is able to investigate the histological features of soft tissue tumours.

METHODS

We reviewed MRIs of soft tissue tumours performed from 2012 to 2015 to calculate the average ADCs. We included 46 patients (27 male; mean age: 57 years, range 12-85 years) with histologically proven soft tissue tumours (10 benign, 2 intermediate 34 malignant) grouped into eight tumour type classes. An experienced pathologist assigned a semi-quantitative cellularity score (very high, high, medium and low) and tumour grading. The t test, ANOVA and linear regression were used to correlate ADC with clinicopathological data. Approximate receiver operating characteristic curves were created to predict possible uses of ADC to differentiate benign from malignant tumours.

RESULTS

There was a significant difference (p < 0.01) in ADCs between these three groups excluding myxoid sarcomas. A significant difference was also evident between the tumour type classes (p < 0.001), grade II and III myxoid lesions (p < 0.05), tumour grading classes (p < 0.001) and cellularity scores classes (p < 0.001), with the lowest ADCs in the very high cellularity. While the linear regression analysis showed a significant relationship between ADC and tumour cellularity (r = 0.590, p ≤ 0.05) and grading (r = 0.437, p ≤ 0.05), no significant relationship was found with age, gender, tumour size and histological subtype. An optimal cut-off ADC value of 1.45 × 10^-3 mm²/s with 76.8% accuracy was found to differentiate benign from malignant tumours.

CONCLUSIONS

DWI may offer adjunctive information about soft tissue tumours, but its clinical role is still to be defined.

Caecal leiomyoma detected by whole-body MRI in a patient with Hodgkin lymphoma: first case report

INTRODUCTION

Hodgkin Lymphoma (HL) is one of the most curable malignant diseases. Modern treatments, like the combined radiochemotherapy and stem cell transplantation, have increased the number of malignant disease survivors. However, HL survivors are at risk of long-term effects, including the development of solid tumors. Secondary neoplasms are a major cause of late morbidity and mortality following treatment for HL.

CASE REPORT

We report the case of a male patient, treated for HL by chemotherapy, who developed a large leiomyoma of the cecum one year after the treatment. A whole-body Magnetic Resonance (WBMRI) scan performed during the follow-up allowed the detection of this incidental caecal mass that was absent in a Computed Tomography (CT) scan performed immediately after the treatment. After a CT-guided biopsy, the lesion was surgically removed and the diagnosis of caecal leiomyoma was obtained.

DISCUSSION

To our knowledge, this is the first case report, according to the scientific literature, of caecal leiomyoma developing after chemotherapy in a HL survivor. Leiomyoma is a rare benign tumor that usually appears as a solitary small mass with a nodular growth and a benign course.

CONCLUSION

This case shows that WB-MRI allows detecting relevant incidental findings during the oncologic follow-up, avoiding both radiation exposure and contrast agent administration. Furthermore, leiomyoma should be considered in the differential diagnosis between the caecal masses with high growth rate.

Whole body MRI with qualitative and quantitative analysis of DWI for assessment of bone marrow involvement in lymphoma

AIM

Our study aimed to investigate the role of qualitative and quantitative whole body MRI with DWI for assessment of bone marrow involvement (BMI) in newly diagnosed lymphoma using FDG PET-CT and bone marrow biopsy (BMB) as reference standard.

MATERIALS AND METHODS

We retrospectively evaluated 56 patients with newly diagnosed lymphoma (21 Hodgkin's lymphoma and 35 non-Hodgkin's lymphoma) who underwent random unilateral BMB, FDG PET-CT and Wb-MRI-DWI for initial staging. In a patient-based analysis, results of Wb-MRI-DWI were compared with FDG PET-CT and BMB. For quantitative analysis, mean ADC values of posterior iliac crest were correlated with BMI and bone marrow cellularity.

RESULTS

WB-MR-DWI obtained excellent concordance with FDG PET-CT both in HL (k = 1.000; 95% CI 1.000-1.000) and in DLBCL (k = 1.000; 95% CI 1.000-1.000). In other NHL, WB-MRI-DWI obtained a good correlation with BMB (k = 0.611; 95% CI 0.295-0.927) while FDG PET-CT had poor concordance (k = 0.067; 95% CI 0.372-0.505). WB-MR-DWI has no false negative errors but 4 false positive results consisting in focal lesions consensually reported by FDG PET-CT and resolved after therapy. No significant correlation between ADC mean value and BMI was found (p = 0.0586).

CONCLUSION

Our data suggest that Wb-MRI-DWI is a valid technique for BMI assessment in lymphoma patients, thanks to its excellent concordance with FDG PET-CT and good concordance with BMB (superior than FDG PET-CT). If further investigations will confirm our results on larger patient groups, it could become a useful tool in the clinical workup.

Whole-body MRI, FDG-PET/CT, and bone marrow biopsy, for the assessment of bone marrow involvement in patients with newly diagnosed lymphoma

PURPOSE

To compare whole-body MRI (WB-MRI) with diffusion-weighted imaging (DWI), FDG-PET/CT, and bone marrow biopsy (BMB), for the evaluation of bone marrow involvement (BMI) in patients with newly diagnosed lymphoma.

MATERIALS AND METHODS

This retrospective study was approved by our Institutional Review Board. Two independent radiologists and one nuclear medicine specialist reviewed all WB-MRI and FDG-PET/CT scans prospectively performed on 104 patients with newly diagnosed lymphoma (53 males; 47 Hodgkin; mean age: 44 years; range, 15-86 years) between 2013 and 2015. The delay between imaging scans and BMBs was up to 10 days. The diagnostic accuracy of WB-MRI (1.5 Tesla MR scanner, with T1w, T2w-STIR, and DWI sequences) was evaluated using BMB and FDG-PET/CT as the reference standard. We applied Cohen's kappa coefficient to assess the inter-observer agreement in WB-MRI interpretation and to compare WB-MRI, FDG-PET/CT and BMB. The Student's t test was done to compare pelvic marrow ADC values of patients with positive and negative BMB. A P-value of < 0.01 was considered significant.

RESULTS

Inter-observer agreement was excellent (k = 0.937). Agreement between WB-MRI and FDG-PET/CT was excellent, with a k = 0.935. Agreement between WB-MRI and BMB was moderate (k = 0.489), and fair between FDG-PET/CT and BMB (k = 0.370). WB-MRI and FDG-PET/CT were falsely negative in four indolent non-Hodgkin lymphomas with BMI < 30% of marrow cellularity. Conversely, WB-MRI and FDG-PET/CT detected all cases with a BMI>30% of marrow cellularity. Mean ADC values in patients with positive and negative BMB were not significantly different (P = 0.049).

CONCLUSION

WB-MRI and FDG-PET/CT are valuable tools for the assessment of BMI.

LEVEL OF EVIDENCE

3 J. Magn. Reson. Imaging 2017;45:1082-1089.

Whole-body MRI in patients with lymphoma: collateral findings

PURPOSE

To assess the incidence of collateral findings detected on whole-body magnetic resonance (WB-MRI) scans performed on patients with lymphoma.

MATERIALS AND METHODS

114 patients (65 male; median age 45.2 years, range 15-86) with histologically confirmed lymphoma (47 Hodgkin, 67 Non-Hodgkin) underwent WB-MRI. The collateral findings were classified into three classes, according to their clinical significance, as follows: not or low significant (class 1), moderately or potentially significant (class 2), and significant (class 3). A Chi-square (χ (2)) test was performed to assess the statistical significance of differences in the incidence of collateral findings based on age (≤50 and >50 years old), gender and histology (Hodgkin and Non-Hodgkin Lymphoma).

RESULTS

Ninety-one of 114 patients (79.8 %) had one or more incidental findings on WB-MRI. Collateral findings were more frequent in class 1 (43 %); abnormalities found in 35 patients (30.7 %) were considered potentially significant, whereas seven patients (6.1 %) demonstrated significant collateral findings requiring immediate treatment or further diagnostic evaluation. Collateral findings were more frequent in subjects over 50 years old compared to those of 50 years old or younger; differences were statistical significant (χ (2) = 8.42, p < 0.05). There were not statistically significant differences related to gender (χ (2) = 0.17, p > 0.05) and histology (χ (2) = 0.24, p > 0.05).

CONCLUSION

WB-MRI is an attractive procedure that allows to detect incidental abnormalities of organs not involved by disease offering the opportunity to obtain an early diagnosis of asymptomatic life-threatening diseases.