PURPOSE: To demonstrate the preliminary feasibility of a longitudinal diffusion magnetic resonance imaging (MRI) strategy for assessing patient response to radiotherapy at 0.35 T using an MRI-guided radiotherapy system (ViewRay). METHODS: Six patients (three head and neck cancer, three sarcoma) who underwent fractionated radiotherapy were enrolled in this study. A 2D multislice spin echo single-shot echo planar imaging diffusion pulse sequence was implemented on the ViewRay system and tested in phantom studies. The same pulse sequence was used to acquire longitudinal diffusion data (every 2-5 fractions) on the six patients throughout the entire course of radiotherapy. The reproducibility of the apparent diffusion coefficient (ADC) measurements was assessed using reference regions and the temporal variations of the tumor ADC values were evaluated. RESULTS: In diffusion phantom studies, the ADC values measured on the ViewRay system matched well with reference ADC values with <5% error for a range of ground truth diffusion coefficients of 0.4-1.1 × 10(-3) mm(2)/s. The remote reference regions (i.e., brainstem in head and neck patients) had consistent ADC values throughout the therapy for all three head and neck patients, indicating acceptable reproducibility of the diffusion imaging sequence. The tumor ADC values changed throughout therapy, with the change differing between patients, ranging from a 40% drop in ADC within the first week of therapy to gradually increasing throughout therapy. For larger tumors, intratumoral heterogeneity was observed. For one sarcoma patient, postradiotherapy biopsy showed less than 10% necrosis score, which correlated with the observed 40% decrease in ADC from the fifth fraction to the eighth treatment fraction. CONCLUSIONS: This pilot study demonstrated that longitudinal diffusion MRI is feasible using the 0.35 T ViewRay MRI. Larger patient cohort studies are warranted to correlate the longitudinal diffusion measurements to patient outcomes. Such an approach may enable response-guided adaptive radiotherapy.
PURPOSE: To demonstrate the preliminary feasibility of a longitudinal diffusion magnetic resonance imaging (MRI) strategy for assessing patient response to radiotherapy at 0.35 T using an MRI-guided radiotherapy system (ViewRay). METHODS: Six patients (three head and neck cancer, three sarcoma) who underwent fractionated radiotherapy were enrolled in this study. A 2D multislice spin echo single-shot echo planar imaging diffusion pulse sequence was implemented on the ViewRay system and tested in phantom studies. The same pulse sequence was used to acquire longitudinal diffusion data (every 2-5 fractions) on the six patients throughout the entire course of radiotherapy. The reproducibility of the apparent diffusion coefficient (ADC) measurements was assessed using reference regions and the temporal variations of the tumor ADC values were evaluated. RESULTS: In diffusion phantom studies, the ADC values measured on the ViewRay system matched well with reference ADC values with <5% error for a range of ground truth diffusion coefficients of 0.4-1.1 × 10(-3) mm(2)/s. The remote reference regions (i.e., brainstem in head and neck patients) had consistent ADC values throughout the therapy for all three head and neck patients, indicating acceptable reproducibility of the diffusion imaging sequence. The tumor ADC values changed throughout therapy, with the change differing between patients, ranging from a 40% drop in ADC within the first week of therapy to gradually increasing throughout therapy. For larger tumors, intratumoral heterogeneity was observed. For one sarcomapatient, postradiotherapy biopsy showed less than 10% necrosis score, which correlated with the observed 40% decrease in ADC from the fifth fraction to the eighth treatment fraction. CONCLUSIONS: This pilot study demonstrated that longitudinal diffusion MRI is feasible using the 0.35 T ViewRay MRI. Larger patient cohort studies are warranted to correlate the longitudinal diffusion measurements to patient outcomes. Such an approach may enable response-guided adaptive radiotherapy.
Authors: John S Ginn; Nzhde Agazaryan; Minsong Cao; Umar Baharom; Daniel A Low; Yingli Yang; Yu Gao; Peng Hu; Percy Lee; James M Lamb Journal: Phys Med Biol Date: 2017-04-20 Impact factor: 3.609
Authors: Narek Shaverdian; Yingli Yang; Peng Hu; Steven Hart; Ke Sheng; James Lamb; Minsong Cao; Nzhde Agazaryan; David Thomas; Michael Steinberg; Daniel A Low; Percy Lee Journal: Br J Radiol Date: 2017-01-12 Impact factor: 3.039
Authors: Ernst S Kooreman; Petra J van Houdt; Rick Keesman; Floris J Pos; Vivian W J van Pelt; Marlies E Nowee; Andreas Wetscherek; Rob H N Tijssen; Marielle E P Philippens; Daniela Thorwarth; Jihong Wang; Amita Shukla-Dave; William A Hall; Eric S Paulson; Uulke A van der Heide Journal: Radiother Oncol Date: 2020-10-02 Impact factor: 6.280
Authors: Rapeepan Maitree; Gloria J Guzman Perez-Carrillo; Joshua S Shimony; H Michael Gach; Anupama Chundury; Michael Roach; H Harold Li; Deshan Yang Journal: J Med Imaging (Bellingham) Date: 2017-09-01
Authors: Siamak P Nejad-Davarani; Niloufar Zakariaei; Yongsheng Chen; E Mark Haacke; Newton J Hurst; M Salim Siddiqui; Lonni R Schultz; James M Snyder; Tobias Walbert; Carri K Glide-Hurst Journal: Med Phys Date: 2020-07-06 Impact factor: 4.071