Correcting B0 inhomogeneity-induced distortions in whole-body diffusion MRI of bone

AbstractDiffusion-weighted magnetic resonance imaging (DWI) of the musculoskeletal system has various applications, including visualization of bone tumors. However, DWI acquired with echo-planar imaging is susceptible to distortions due to static magnetic field inhomogeneities. This study aimed to estimate spatial displacements of bone and to examine whether distortion corrected DWI images more accurately reflect underlying anatomy. Whole-body MRI data from 127 prostate cancer patients were analyzed. The reverse polarity gradient (RPG) technique was applied to DWI data to estimate voxel-level distortions and to produce a distortion corrected DWI dataset. First, an anatomic landmark analysis was conducted, in which corresponding vertebral landmarks on DWI and anatomic T2-weighted images were annotated. Changes in distance between DWI- and T2-defined landmarks (i.e., changes in error) after distortion correction were calculated. In secondary analyses, distortion estimates from RPG were used to assess spatial displacements of bone metastases. Lastly, changes in mutual information between DWI and T2-weighted images of bone metastases after distortion correction were calculated. Distortion correction reduced anatomic error of vertebral DWI up to 29 mm. Error reductions were consistent across subjects (Wilcoxon signed-rank p < 10–20). On average (± SD), participants’ largest error reduction was 11.8 mm (± 3.6). Mean (95% CI) displacement of bone lesions was 6.0 mm (95% CI 5.0–7.2); maximum displacement was 17.1 mm. Corrected diffusion images were more similar to structural MRI, as evidenced by consistent increases in mutual information (Wilcoxon signed-rank p < 10–12). These findings support the use of distortion correction techniques to improve localization of bone on DWI.

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Correcting B0 inhomogeneity-induced distortions in whole-body diffusion MRI of bone metastases

10.1101/2020.11.22.20236547 ◽

2020 ◽

Author(s):

Leonardino A. Digma ◽

Christine H. Feng ◽

Christopher C. Conlin ◽

Ana E. Rodríguez-Soto ◽

Kanha Batra ◽

...

Keyword(s):

Prostate Cancer ◽

Bone Metastases ◽

Bone Lesion ◽

Distortion Correction ◽

Whole Body ◽

Bone Lesions ◽

Thoracic Vertebrae ◽

Signed Rank ◽

Spatial Displacements ◽

T2 Weighted Images

AbstractBackgroundAccurate imaging of bone metastases is necessary for treatment planning and assessing treatment response. Diffusion-weighted magnetic resonance imaging (DWI) can detect bone metastases, but DWI acquired with echo-planar imaging is susceptible to distortions due to static magnetic field inhomogeneities.PurposeEstimate spatial displacements of bone lesions on DWI. Examine whether distortion-corrected DWI more accurately reflects underlying anatomy.Study TypeRetrospective.Subjects18 patients with prostate cancer bone metastases.Field Strength/Sequence3.0 T; DWI and T2-weighted imaging.AssessmentWe first applied the reverse polarity gradient (RPG) technique to estimate spatial displacements of bone metastasis on DWI. Next, we calculated changes in mutual information (MI) between DWI and T2-weighted images after RPG distortion correction. Further, we annotated skeletal landmarks on DWI and T2-weighted images. RPG was again used to estimate displacements of these landmarks. Lastly, we calculated changes in distance between DWI- and T2-defined landmarks (i.e., changes in error) after RPG distortion correction.Statistical TestsMean and bootstrap-derived confidence intervals were used to summarize variables that estimate bone lesion distortions. Wilcoxon signed-rank tests were used to assess change in MI between DWI and T2-weighted images after RPG.ResultsMean (95% CI) displacement of bone lesions was 5.6 mm (95% CI: 4.8-6.5); maximum displacement was 17.1 mm. Corrected diffusion images were more similar to structural MRI, as evidenced by consistent increases in MI after applying RPG (Wilcoxon signed-rank p<10−13). Like bone metastases, our annotated skeletal landmarks also underwent substantial displacement (average, 6.3 mm). Lastly, RPG led to consistent error reductions between DWI and T2 for each skeletal landmark (mean, [95% CI]): thoracic vertebrae (−3.8 mm, [-4.3,-3.3]), abdominal vertebrae (−1.0 mm, [-1.2,-0.71]), pelvic vertebrae (−0.6 mm, [-1.0,-0.17]), and femoral head (−1.2 mm, [-2.1,-0.4]).Data ConclusionsThese findings support the use of distortion correction techniques to improve localization of bone metastases on DWI.Grant SupportThis work was supported by NIH/NIBIB #K08EB026503, American Society for Radiation Oncology, and the Prostate Cancer Foundation. This work was further supported by the National Institute on Aging T35 grant AG26757 (PI: Dilip V. Jeste, MD, and Alison Moore, MD, MPH), and the Stein Institute for Research on Aging and the Center for Healthy Aging at the University of California, San Diego.

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68Ga-P15-041, A Novel Bone Imaging Agent for Diagnosis of Bone Metastases

Frontiers in Oncology ◽

10.3389/fonc.2021.766851 ◽

2021 ◽

Vol 11 ◽

Author(s):

Rui Guo ◽

Xiangxi Meng ◽

Fei Wang ◽

Jiangyuan Yu ◽

Qing Xie ◽

...

Keyword(s):

Nuclear Medicine ◽

Bone Metastases ◽

Cancer Patients ◽

Predictive Value ◽

Characteristic Curve ◽

Whole Body ◽

Bone Lesions ◽

Pet Ct ◽

Patlak Analysis ◽

Parametric Maps

Objectives68Ga-P15-041 (68Ga-HBED-CC-BP) is a novel bone-seeking PET radiotracer, which can be readily prepared by using a simple kit formulation and an in-house 68Ga/68Ge generator. The aim of this study is to assess the potential human application of 68Ga-P15-041 for clinical PET/CT imaging and to compare its efficacy to detect bone metastases of different cancers with 99mTc-MDP whole-body bone scintigraphy (WBBS).MethodsInitial kinetic study using Patlak analysis and parametric maps were performed in five histopathologically proven cancer patients (three males, two females) using 68Ga-P15-041 PET/CT scan only. Another group of 51 histopathologically proven cancer patients (22 males, 29 females) underwent both 99mTc-MDP WBBS and 68Ga-P15-041 PET/CT scans within a week, sequentially. Using either pathology examination or follow-up CT or MRI scans as the gold standard, the diagnostic efficacy and receiver operating characteristic curve (ROC) of the two methods in identifying bone metastases were compared (p <0.05, statistically significant).ResultsFifty-one patients were imaged, and 174 bone metastatic sites were identified. 68Ga-P15-041 PET/CT and 99mTc-MDP WBBS detected 162 and 81 metastases, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 68Ga-P15-041 PET/CT and 99mTc-MDP WBBS were 93.1% vs 81.8%, 89.8% vs 90.7%, 77.5% vs 69.2%, 97.2% vs 93.4% and 90.7% vs 88.4%, respectively. Our results showed that the mean of SUVmax was significantly higher in metastases than that in benign lesions, 15.1 ± 6.9 vs. 5.6 ± 1.3 (P <0.001). Using SUVmax = 7.6 as the cut-off value by PET/CT, it was possible to predict the occurrence of metastases (AUC = 0.976; P <0.001; 95% CI: 0.946–0.999). However, it was impossible to distinguish osteoblastic bone metastases from osteolytic bone lesions. Parametric maps based on Patlak analysis provided excellent images and highly valuable quantitative information.Conclusions68Ga-P15-041 PET/CT, offering a rapid bone scan and high contrast images in minutes, is superior to the current method of choice in detecting bone metastases. It is reasonable to suggest that 68Ga-P15-041 PET/CT could become a valuable routine nuclear medicine procedure in providing excellent images for detecting bone metastases in cancer patients. 68Ga-P15-041 could become a valuable addition expanding the collection of 68Ga-based routine nuclear medicine procedures where 18F fluoride is not currently available.

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Bone Metastases Are Measurable: The Role of Whole-Body MRI and Positron Emission Tomography

Frontiers in Oncology ◽

10.3389/fonc.2021.772530 ◽

2021 ◽

Vol 11 ◽

Author(s):

Daniela E. Oprea-Lager ◽

Matthijs C.F. Cysouw ◽

Ronald Boellaard ◽

Christophe M. Deroose ◽

Lioe-Fee de Geus-Oei ◽

...

Keyword(s):

Positron Emission Tomography ◽

Bone Metastases ◽

Bone Lesion ◽

Response Assessment ◽

Emission Tomography ◽

Whole Body ◽

Bone Lesions ◽

Cancer Type ◽

Current Response ◽

Positron Emission

Metastatic tumor deposits in bone marrow elicit differential bone responses that vary with the type of malignancy. This results in either sclerotic, lytic, or mixed bone lesions, which can change in morphology due to treatment effects and/or secondary bone remodeling. Hence, morphological imaging is regarded unsuitable for response assessment of bone metastases and in the current Response Evaluation Criteria In Solid Tumors 1.1 (RECIST1.1) guideline bone metastases are deemed unmeasurable. Nevertheless, the advent of functional and molecular imaging modalities such as whole-body magnetic resonance imaging (WB-MRI) and positron emission tomography (PET) has improved the ability for follow-up of bone metastases, regardless of their morphology. Both these modalities not only have improved sensitivity for visual detection of bone lesions, but also allow for objective measurements of bone lesion characteristics. WB-MRI provides a global assessment of skeletal metastases and for a one-step “all-organ” approach of metastatic disease. Novel MRI techniques include diffusion-weighted imaging (DWI) targeting highly cellular lesions, dynamic contrast-enhanced MRI (DCE-MRI) for quantitative assessment of bone lesion vascularization, and multiparametric MRI (mpMRI) combining anatomical and functional sequences. Recommendations for a homogenization of MRI image acquisitions and generalizable response criteria have been developed. For PET, many metabolic and molecular radiotracers are available, some targeting tumor characteristics not confined to cancer type (e.g. 18F-FDG) while other targeted radiotracers target specific molecular characteristics, such as prostate specific membrane antigen (PSMA) ligands for prostate cancer. Supporting data on quantitative PET analysis regarding repeatability, reproducibility, and harmonization of PET/CT system performance is available. Bone metastases detected on PET and MRI can be quantitatively assessed using validated methodologies, both on a whole-body and individual lesion basis. Both have the advantage of covering not only bone lesions but visceral and nodal lesions as well. Hybrid imaging, combining PET with MRI, may provide complementary parameters on the morphologic, functional, metabolic and molecular level of bone metastases in one examination. For clinical implementation of measuring bone metastases in response assessment using WB-MRI and PET, current RECIST1.1 guidelines need to be adapted. This review summarizes available data and insights into imaging of bone metastases using MRI and PET.

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Intraindividual comparison of [11C]acetate and [11C]choline PET for detection of metastases of prostate cancer

Nuklearmedizin ◽

10.1055/s-0038-1623902 ◽

2003 ◽

Vol 42 (01) ◽

pp. 25-30 ◽

Cited By ~ 106

Author(s):

B. G. Volkmer ◽

G. Glatting ◽

J. van den Hoff ◽

J. E. Gschwend ◽

P. Messer ◽

...

Keyword(s):

Prostate Cancer ◽

Lymph Node ◽

Local Recurrence ◽

Bone Metastases ◽

Primary Tumour ◽

Lymph Node Involvement ◽

Interindividual Variation ◽

Whole Body ◽

Bone Lesions ◽

Node Involvement

AbstractIn a pilot trial we investigated whether significant differences in prostate cancer (PCA) imaging would be observed using [11C]acetate and [11C]choline positron emission tomography (PET). Methods: Twelve patients were studied with both radiotracers. Whole body PET without attenuation correction was performed after injection of 0.95 ± 0.15 GBq [11C]acetate and 0.84 ± 0.13 GBq [11C]choline, respectively, from 5 to 60 min p. i. Focally increased uptake in bone, below the urinary bladder or in a lymph node region was considered as tumour. Primary tumour, lymph node involvement, bone metastases, local recurrence; and no evidence of disease were known in 2, 4, 2, 2; and 2 patients, respectively. Results: [11C]Acetate uptake was highest in spleen and pancreas while [11C]choline uptake was predominant in liver and kidney parenchyma. However, interindividual variation was high. The potential of both radiotracers to detect known bone lesions, lymph node metastases, and imaging of the primary tumour was identical. However, both failed to detect a small local recurrence in two patients as well as to demonstrate lymph node involvement in one patient, which was confirmed by surgery. Conclusions: In this preliminary study, uptake of both radiotracers in prostate cancer or its metastases was nearly identical and none of them should be favoured. At present, both radiotracers influence patient management by detection of local recurrence, lymph node, or bone metastases of PCA.

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Assessment of bone metastases in patients (pts) with urothelial carcinoma using 18F-sodium fluoride PET/CT (18F-NaF) versus 18F-fluorodeoxyglucose PET/CT (18F-FDG).

Journal of Clinical Oncology ◽

10.1200/jco.2014.32.4_suppl.329 ◽

2014 ◽

Vol 32 (4_suppl) ◽

pp. 329-329

Author(s):

Benjamin Adam Weinberg ◽

Maria Liza Lindenberg ◽

Karen A. Kurdziel ◽

Seth M. Steinberg ◽

David J. Liewehr ◽

...

Keyword(s):

Bone Metastases ◽

Stable Disease ◽

Rank Test ◽

Bone Lesions ◽

Planar Imaging ◽

Median Difference ◽

Standardized Uptake Values ◽

Pet Ct ◽

Medicine Physician ◽

Signed Rank Test

329 Background: 18F-NaF has shown improved sensitivity for bone imaging when compared to conventional planar imaging or SPECT/CT using 99mTc-MDP. We compared the number of bone lesions detected on 18F-NaF versus 18F-FDG in urothelial cancer pts with known bone metastases undergoing treatment. Methods: Pts enrolled in a prospective single-arm phase II study of cabozantinib underwent 18F-NaF and 18F-FDG scans at baseline and at 8 weeks of therapy. In a lesion-based analysis independently confirmed by a nuclear medicine physician, abnormal foci of radiotracer uptake were categorized by location (skull, spine, pelvis, thorax, or long bones) and by disease state (benign, malignant, or indeterminate). A patient-based analysis was performed to determine if findings indicated disease progression, stable disease, or improvement of disease, based on the number of lesions and standardized uptake values (SUVs). Results: 294 total bone lesions were identified at baseline in 10 pts (8 male and 2 female, ages 44-73). 18F-NaF identified more lesions than 18F-FDG at baseline, 294 vs. 119. In a paired analysis, the median difference was 11.5 more lesions detected per patient on 18F-NaF vs. 18F-FDG (by Wilcoxon signed-rank test, p = 0.023). More total thoracic bone lesions at baseline, 100 vs. 23, were also detected on 18F-NaF vs. 18F-FDG, median 6.5 vs. 1.0 with a median difference of 6 more lesions per patient on 18F-NaF (p = 0.016). 18F-NaF also detected more skull lesions at baseline, 19 vs. 1, which was clinically but not statistically significant (p = 0.250). There was general concordance in the patient-based analysis; only 1 18F-NaF scan demonstrated progressive disease while its corresponding 18F-FDG scan showed stable disease. Conclusions:18F-NaF identified more lesions than 18F-FDG at baseline, making it a good staging exam. However, there was agreement between 18F-NaF and 18F-FDG in terms of tumor response in almost all the follow-up scans. Therefore, although a greater number of bone lesions are seen in 18F-NaF compared with 18F-FDG, the clinical significance in assessing treatment response remains to be determined. Clinical trial information: NCT01688999.

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Correction of Artifacts Induced by B0 Inhomogeneities in Breast MRI using Reduced Field-of-View Echo-Planar Imaging and Enhanced Reverse Polarity Gradient Method

10.1101/2020.03.31.20048900 ◽

2020 ◽

Author(s):

Ana E. Rodríguez-Soto ◽

Helen Park ◽

Dominic Holland ◽

Kathryn E. Keenan ◽

Hauke Bartsch ◽

...

Keyword(s):

Breast Imaging ◽

Pulse Sequences ◽

Echo Planar Imaging ◽

Distortion Correction ◽

Field Of View ◽

Planar Imaging ◽

Reverse Polarity ◽

Maximum Displacement ◽

Breast Phantom ◽

Echo Planar

AbstractPurposeDiffusion weighted (DW) echo-planar imaging (EPI) is prone to geometric and intensity distortions due to B0 inhomogeneities. Pulse sequences that excite spins within a reduced field-of-view (FOV) in the phase encoding (PE) direction have been developed to decrease such distortions. In addition, use of the reverse polarity gradient (RPG) method, a retrospective approach to correct distortion artifacts, has been shown to improve the localization of tumor lesions. The purpose of this work was to evaluate the performance of reduced-FOV acquisition and RPG in decreasing distortion artifacts for breast imaging.MethodsEPI data were acquired with full and reduced-FOV in a breast phantom and in a group of 170 women at 3T. The performance of RPG in correcting distortion artifacts in EPI data was evaluated using the mutual information (MI) metric between EPI and anatomical low-distortion images before and after distortion correction.ResultsRPG corrected distortions by 61% in full-FOV EPI and 48% in reduced-FOV EPI in a breast phantom. In patients, MI increased on average 13±8% and 8±6% for both full and reduced-FOV EPI data after distortion correction, respectively. The 95th percentile and maximum displacement between uncorrected and corrected full-FOV EPI datasets were 0.8±0.3cm and 1.9±0.3cm, and for reduced-FOV were 0.4±0.2cm and 1.3±0.3cm.ConclusionMinimal distortion was achieved with RPG applied to reduced-FOV EPI data. RPG improved distortions for full-FOV, but with more modest improvements and limited correction near the nipple.

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Multiple Metastasis-Like Bone Lesions in Scintigraphic Imaging

Journal of Biomedicine and Biotechnology ◽

10.1155/2012/957364 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Ying Zhang ◽

Chunlei Zhao ◽

Hongbiao Liu ◽

Haifeng Hou ◽

Hong Zhang

Keyword(s):

Bone Metastases ◽

Eosinophilic Granuloma ◽

Clinical Work ◽

Whole Body ◽

Bone Lesions ◽

Osteolytic Lesions ◽

Multiple Imaging ◽

Imaging Results ◽

Multiple Bone Metastases ◽

Treatment Procedures

Multiple benign osteolytic lesions are very hard to differentiate from disseminated bone metastasis. Whole-body bone scintigraphy (WBBS) with technetium-99m methylene diphosphonate (Tc-99m MDP) demonstrates multiple lesions with increased uptake in any bone involved. Even combined with medical history and multiple imaging results, such as MRI and CT, the clinical diagnosis of metastasis lesion remains as a challenge. These clinical characteristics are similar to multiple malignant bone metastases and therefore affect the following treatment procedures. In this paper, we analyzed multiple benign osteolytic lesions, like eosinophilic granuloma (EG), multiple myeloma (MM), disseminated tuberculosis, fibrous dysplasia, or enchondroma, occurring in our daily clinical work and concluded that additional attention should be paid before giving the diagnosis of multiple bone metastases.

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Age- and sex-related bone uptake of Tc-99m-HDP measured by whole-body bone scanning

Nuklearmedizin ◽

10.1055/s-0038-1632258 ◽

2000 ◽

Vol 39 (05) ◽

pp. 127-132 ◽

Cited By ~ 2

Author(s):

Nicole Sieweke ◽

K. H. Bohuslavizki ◽

W. U. Kampen ◽

M. Zuhayra ◽

M. Clausen ◽

...

Keyword(s):

Whole Body ◽

Bone Lesions ◽

Men And Women ◽

Bone Uptake ◽

Normal Bone ◽

Age Related ◽

Number Of Patients ◽

Wide Range ◽

Bone Scans ◽

Body Bone

Summary Aim of this study was to validate a recently introduced new and easy-to-perform method for quantifying bone uptake of Tc-99m-labelled diphosphonate in a routine clinical setting and to establish a normal data base for bone uptake depending on age and gender. Methods: In 49 women (14-79 years) and 47 men (6-89 years) with normal bone scans as well as in 49 women (33-81 years) and 37 men (27-88 years) with metastatic bone disease whole-body bone scans were acquired at 3 min and 3-4 hours p.i. to calculate bone uptake after correction for both urinary excretion and soft tissue retention. Results: Bone uptake values of various age-related subgroups showed no significant differences between men and women (p >0.05 ). Furthermore, no differences could be proven between age-matched subgroups of normals and patients with less than 10 metastatic bone lesions, while patients with wide-spread bone metastases revealed significantly increased uptake values. In both men and women highest bone uptake was obtained (p <0.05 ) in subjects younger than 20 years with active epiphyseal growth plates. In men, bone uptake slowly decreased with age up to 60 years and then showed a tendency towards increasing uptake values. In women, the mean uptake reached a minimun in the decade 20-29 years and then slowly increased with a positive linear correlation of age and uptake in subjects older than 55 years (r = 0.57). Conclusion: Since the results proposed in this study are in good agreement with data from literature, the new method used for quantification could be validated in a large number of patients. Furthermore, age- and sexrelated normal bone uptake values of Tc-99m-HDP covering a wide range of age could be presented for this method as a basis for further studies on bone uptake.

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Immunszintigraphie mit 111ln-DTPA-markierten monoklonalen Antikörpern: Vergleich zwischen ECT und planarer Szintigraphie

Nuklearmedizin ◽

10.1055/s-0038-1628900 ◽

1987 ◽

Vol 26 (06) ◽

pp. 258-262

Author(s):

J. Happi ◽

R. P. Baum ◽

J. Frohn ◽

B. Weimer ◽

A. Halbsguth ◽

...

Keyword(s):

Imaging Techniques ◽

Diagnostic Procedures ◽

Undifferentiated Carcinoma ◽

Whole Body ◽

Acquisition Time ◽

Planar Imaging ◽

Primary Tumors ◽

Intraindividual Comparison ◽

Single Detector ◽

Increased Sensitivity

The present study was done in order to examine if the use of111ln-DTPA- labeled MAb fragments in place of 131l-labeled MAb fragments increases the sensitivity of tomographic immunoscintigraphy to reach the level of that of planar imaging techniques. In 11 patients with various primary tumors, local recurrences or metastases [colorectal carcinoma (n = 7), ovarian carcinoma (n = 2), papillary thyroid carcinoma (n = 1), undifferentiated carcinoma of the lung (n = 1)], immunoscintigraphy (IS) was carried out using 111ln-DTPA- labeled F(ab’)2 fragments of various MAbs (anti-CEA, OC 125, anti-hTG) and planar and tomographic imaging were compared intraindividually. By conventional diagnostic procedures, the presence of a tumor mass was confirmed (transmission computer tomography, ultrasound) or verified (131l whole-body scintigraphy, histology) in all cases. Immunoscintigraphy was positive in 9 out of 11 cases by ECT and in 10 out of 11 cases by planar imaging. When using 111 In-labeled MAb fragments, intraindividual comparison of ECT and planar imaging resulted in a similar sensitivity. The increased sensitivity of ECT using this tracer in contrast to 131l-labeled MAb fragments may be attributed to the fact that the physical properties of111 In are much more suitable for the gamma cameras most commonly used (single detector, 3/8” crystal); using 111 In-labeled MAb fragments, count rates sufficient for ECT can be obtained within a reasonable acquisition time. This allows to combine IS with the advantages of ECT regarding tumour localization and prevention of artefacts due to superposition of background.

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Diagnostic Value of Whole-Body MRI Short Protocols in Bone Lesion Detection in Multiple Myeloma Patients

Diagnostics ◽

10.3390/diagnostics11061053 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1053

Author(s):

Davide Ippolito ◽

Teresa Giandola ◽

Cesare Maino ◽

Davide Gandola ◽

Maria Ragusi ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow Involvement ◽

Bone Lesion ◽

Diagnostic Value ◽

Lesion Detection ◽

Lower Limbs ◽

Whole Body ◽

Bone Lesions ◽

Whole Body Mri ◽

Mri Protocol

The aim of the study is to evaluate the effectiveness of short whole-body magnetic resonance imaging (WBMRI) protocols for the overall assessment of bone marrow involvement in patients with multiple myeloma (MM), in comparison with standard whole-body MRI protocol. Patients with biopsy-proven MM, who underwent a WBMRI with full-body coverage (from vertex to feet) were retrospectively enrolled. WBMRI images were independently evaluated by two expert radiologists, in terms of infiltration patterns (normal, focal, diffuse, and combined), according to location (the whole skeleton was divided into six anatomic districts: skull, spine, sternum and ribs, upper limbs, pelvis and proximal two-thirds of the femur, remaining parts of lower limbs) and lytic lesions number (<5, 5–20, and >20). The majority of patients showed focal and combined infiltration patterns with bone lesions predominantly distributed in the spine and pelvis. As skull and lower limbs are less frequently involved by focal bone lesions, excluding them from the standard MRI protocol allows to obtain a shorter protocol, maintaining a good diagnostic value.

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