Radiotherapy Response Assessment of Multiple Myeloma: A Dual-Energy CT Approach With Virtual Non-Calcium Images

Abstract

BackgroundLife expectancy of patients with multiple myeloma (MM) has increased over the past decades, underlining the importance of local tumor control and avoidance of dose-dependent side effects of palliative radiotherapy (RT). Virtual noncalcium (VNCa) imaging from dual-energy computed tomography (DECT) has been suggested to estimate cellularity and metabolic activity of lytic bone lesions (LBLs) in MM.ObjectiveTo explore the feasibility of RT response monitoring with DECT-derived VNCa attenuation measurements in MM.MethodsThirty-three patients with 85 LBLs that had been irradiated and 85 paired non-irradiated LBLs from the same patients were included in this retrospective study. Irradiated and non-irradiated LBLs were measured by circular regions of interest (ROIs) on conventional and VNCa images in a total of 216 follow-up measurements (48 before and 168 after RT). Follow-ups were rated as therapy response, stable disease, or local progression according to the MD Anderson criteria. Receiver operating characteristic (ROC) analysis was performed to discriminate irradiated vs. non-irradiated and locally progressive vs. stable/responsive LBLs using absolute attenuation post-irradiation and percentage attenuation change for patients with pre-irradiation DECT, if available.ResultsAttenuation of LBLs decreased after RT depending on the time that had passed after irradiation [absolute thresholds for identification of irradiated LBLs 30.5–70.0 HU [best area under the curve [AUC] 0.75 (0.59–0.91)] and -77.0 to -22.5 HU [best AUC 0.85 (0.65–1.00)]/-50% and -117% to -167% proportional change of attenuation on conventional and VNCa images, respectively]. VNCa CT was significantly superior for identification of RT effects in LBLs with higher calcium content [best VNCa AUC 0.96 (0.91–1.00), best conventional CT AUC 0.64 (0.45–0.83)]. Thresholds for early identification of local irradiation failure were >20.5 HU on conventional CT [AUC 0.78 (0.68–0.88)] and >-27 HU on VNCa CT [AUC 0.83 (0.70–0.96)].ConclusionTherapy response of LBLs after RT can be monitored by VNCa imaging based on regular myeloma scans, which yields potential for optimizing the lesion-specific radiation dose for local tumor control. Decreasing attenuation indicates RT response, while above threshold attenuation of LBLs precedes local irradiation failure.

Dual-Energy CT, Virtual Non-Calcium Bone Marrow Imaging of the Spine: An AI-Assisted, Volumetric Evaluation of a Reference Cohort with 500 CT Scans

“…Hence, we suggest that the age-dependent increase in bone marrow attenuation in our study is a result of decreasing bone mineral density, i.e., virtual calcium suppression of voxels with higher calcium-like attenuation results in relatively lower VNCa attenuation. Similarly, iodine uptake of the bone marrow might affect VNCa attenuation: Thus far, most VNCa studies of malignant bone marrow disease are restricted to non-contrast-enhanced scans [17][18][19][20][21][22][23]. A possible explanation is that virtual suppression of calcium-like attenuation might interfere with iodine-like attenuation [12,37].…”

“…This technique aims to virtually remove the trabecular structure of the vertebral body and enables dedicated bone marrow imaging of the spine [12]. Several recent studies suggest similar capabilities of VNCa images, compared with the gold standards MRI and PET/CT, when assessing malignant infiltration of the spine's bone marrow [12,[17][18][19][20][21][22][23] or traumatic vertebral bone marrow alterations [24,25]. While study-specific cutoffs have been provided for these purposes, knowledge on the distribution and variability of VNCa values encountered in healthy individuals is sparse.…”

Dual-Energy CT in Oncologic Imaging

“…In addition to aiding in diagnosis, iodine maps allow for the evaluation of the response to therapy [ 84 , 85 , 86 ]. Some lesions initially respond to therapy with a reduction in vascularity (and therefore iodine uptake) rather than a reduction in size [ 86 ], which is particularly true in post-chemotherapy evaluations with antiangiogenic drugs or tyrosine kinase inhibitors.…”

“…Some lesions initially respond to therapy with a reduction in vascularity (and therefore iodine uptake) rather than a reduction in size [ 86 ], which is particularly true in post-chemotherapy evaluations with antiangiogenic drugs or tyrosine kinase inhibitors. In the study by Fervers et al [ 84 ], therapy response of multiple myeloma after radiotherapy was monitored by using virtual non-calcium imaging, which yields potential for optimizing the lesion-specific radiation dose for local tumor control. In this study, decreasing attenuation indicates RT response, while above-threshold attenuation lesions precede local irradiation failure.…”

Mieloma múltiplo: indivíduos mais acometidos, seus sintomas, diagnóstico e tratamento: uma análise literária

“…Uma opção de tratamento mais importante é a radioterapia percutânea, onde, muitos estudos comprovaram a redução dos sintomas, além da utilização de doses mínimas de radiação, tendo uma percepção de melhora pelos pacientes com MM, além de uma redução no risco de fraturas ósseas. (KLAUS, et al, 2009;ZARGHOONI, et al, 2018;LANG, et al, 2017;SALEMA;CARVALHO, 2019;GENG, et al, 2022;SIVE, et al, 2021, FERVERS, et al, 2021LEUMIEUX, et al, 2021;VIEIRA, et al, 2020).…”