Siddharth Saraiya

Apparent diffusion coefficient (ADC) change on repeated diffusion-weighted magnetic resonance imaging during radiochemotherapy for non-small cell lung cancer: A pilot study

OBJECTIVES Serial diffusion-weighted magnetic resonance imaging (DW-MRI) during radiochemotherapy of non-small cell lung cancer (NSCLC) is analyzed to investigate the apparent diffusion coefficient (ADC) as a potential biomarker for tumor response. METHODS Ten patients underwent DW-MRI prior to and at three and six weeks during radiochemotherapy. Three methods of contouring primary tumors (PT) were performed to evaluate the impact of tumor heterogeneity on ADC values: PTT: whole tumor volume; PTT-N: PTT-necrosis; PTL: small volume of presumed active tumor with low ADC value. Pretreatment and during-treatment absolute ADC values and ADC value changes were analyzed for PT and involved lymph nodes (LN). RESULTS ADC values for PTT, PTT-N, PTL and LN increased by 8-14% (PT) and 15% (LN) at three weeks, and 19-26% and 23% at 6 weeks post initial treatment (p=0.04-0.002). Average percent ADC value increase was smaller than tumor volume regression (p=0.06-0.0005). Patients with overall survival <12 months had a lower increase of ADC values compared to longer surviving patients (p=0.008 for PTT). CONCLUSIONS Significant ADC value increases during radiochemotherapy for non-small cell lung cancer were observed. ADC value change during treatment appears to be an independent marker of patient outcome and warrants further investigation.

Estimation of optimal b-value sets for obtaining apparent diffusion coefficient free from perfusion in non-small cell lung cancer

The purpose of this study was to determine optimal sets of b-values in diffusion-weighted MRI (DW-MRI) for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in non-small cell lung cancer. Ten subjects had 40 DW-MRI scans before and during radiotherapy in a 1.5 T MRI scanner. Respiratory triggering was applied to the echo-planar DW-MRI with TR ≈ 4500 ms, TE  =  74 ms, eight b-values of 0-1000 μs μm(-2), pixel size  =  1.98 × 1.98 mm(2), slice thickness  =  6 mm, interslice gap  =  1.2 mm, 7 axial slices and total acquisition time ≈6 min. One or more DW-MRI scans together covered the whole tumour volume. Monoexponential model ADC values using various b-value sets were compared to reference-standard ADCIVIM values using all eight b-values. Intra-scan coefficient of variation (CV) of active tumour volumes was computed to compare the relative noise in ADC maps. ADC values for one pre-treatment DW-MRI scan of each of the 10 subjects were computed using b-value pairs from DW-MRI images synthesized for b-values of 0-2000 μs μm(-2) from the estimated IVIM parametric maps and corrupted by various Rician noise levels. The square root of mean of squared error percentage (RMSE) of the ADC value relative to the corresponding ADCIVIM for the tumour volume of the scan was computed. Monoexponential ADC values for the b-value sets of 250 and 1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; and 250-1000 μs μm(-2) were not significantly different from ADCIVIM values (p > 0.05, paired t-test). Mean error in ADC values for these sets relative to ADCIVIM were within 3.5%. Intra-scan CVs for these sets were comparable to that for ADCIVIM. The monoexponential ADC values for other sets-0-1000; 50-1000; 100-1000; 500-1000; and 250 and 800 μs μm(-2) were significantly different from the ADCIVIM values. From Rician noise simulation using b-value pairs, there was a wide range of acceptable b-value pairs giving small RMSE of ADC values relative to ADCIVIM. The pairs for small RMSE had lower b-values as the noise level increased. ADC values of a two b-value set-250 and 1000 μs μm(-2), and all three b-value sets with 250, 1000 μs μm(-2) and an intermediate value approached ADCIVIM, with relative noise comparable to that of ADCIVIM. These sets may be used in lung tumours using comparatively short scan and post-processing times. Rician noise simulation suggested that the b-values in the vicinity of these experimental best b-values can be used with error within an acceptable limit. It also suggested that the optimal sets will have lower b-values as the noise level becomes higher.

Patient-reported outcomes after electron radiation treatment for early-stage palmar and plantar fibromatosis

PURPOSE Palmar and plantar fibromatosis (PPF) is a progressive connective tissue disorder of the hand/foot that often leads to debilitating functional impairment. In Europe, orthovoltage radiation therapy (RT) has been demonstrated to prevent local disease progression for up to 80% of patients with early-stage PPF. There are limited data reporting outcomes for populations outside of Europe or using electron RT. METHODS AND MATERIALS Between 2008 and 2013, 44 early-stage PPF cases received RT. RT fields involved clinically defined targets encompassing involved areas (skin changes, cords, nodules) with at least 1.5-cm margins. En face electrons (6-12 MeV) and bolus (0.5-1 cm) were selected individually. Outcomes are reported for patients who participated in an institutional review board-approved standardized questionnaire and chart review. RESULTS Thirty-three patients received 66 treatments (45 hands/15 feet and 6 reirradiations). Most frequent dose schemes were 21 Gy (3 Gy in 7 fractions) and 30 Gy (3 Gy in 10 fractions with 6- to 8-week breaks after 15 Gy). Median time to follow-up survey was 31 months. Disease progression at any location within or outside the RT treatment field occurred in 20 of 33 patients (61%). Fourteen of 60 sites (23%) developed in-field progression, but 4 sites were successfully reirradiated with final local control in 50 of 60 sites (83%). RT improved pretreatment symptoms of pain with strain at 30 of 37 sites (81%) and itch/burn sensations at 17 of 21 sites (81%). There were no reported grade ≥2 late toxicities even with reirradiation. Patient reported overall success with treatment was 31 of 33 patients (94%). CONCLUSION PPF is a progressive disease. En face electron RT is an effective therapy that stabilizes or improves symptoms in the majority of patients. Reirradiation can be considered as a treatment option for in-field progression. Patients report minimal toxicity and a high rate of satisfaction with treatment.

In Regard to Shusharina et al

women may have very low risk of local relapse with adjuvant hormone therapy alone, but prospective evaluation with adequate follow-up is mandatory before routine clinical implementation. We maintain that breast-conserving surgery followed by whole-breast radiation therapy remains the standard local management for women with early-stage breast cancer. Although alternative approaches such as intraoperative partial-breast irradiation or omission of radiation in highly selected subgroups may be promising prospects for the future, they are experimental and must undergo rigorous prospective evaluation with long-term follow-up before they can replace standard treatment.

Phase I/II study of hypofractionated intensity modulated radiotherapy (IMRT) for prostate cancer including simultaneously integrated boost (SIB).

67 Background: The purpose of this study is to evaluate the toxicity of hypofractionationed H- IMRT treatment including SIB IMRT when pelvic nodes were covered. Additionally, we assessed early treatment efficacy through PSA control (biochemical failure defined as PSA more than nadir + 2 ng/mL). Methods: Men with localized prostate cancer were enrolled in a phase I/II trial to receive H-IMRT to the prostate, seminal vesicles)(SV) and pelvic lymph nodes (LN) using simultaneous integrated boost (SIB) method. Low risk (LR) patients received 69.4 Gy to the prostate only in 29 fractions. The intermediate (IR) and high risk (HR) patients received 72 Gy to the prostate, 54 Gy to the proximal 1 cm SV, and 50.4 Gy to the pelvic LN when risk of LN involvement >15% by Roach formula. Treatment was given in 30 fractions using intraprostatic fiducials and daily image guidance. PTV expansion for prostate and SV was 0.3 mm posteriorly and 0.7 cm in all other directions. The IR and HR patients received androgen deprivation...

TH‐CD‐207‐10: Effect of Noise On the Optimal B‐Value Pairs for Obtaining Perfusion‐Insensitive Apparent Diffusion Coefficient in Diffusion‐Weighted MRI

Purpose: Monoexponential model using typically two or three b-values is used in clinical diffusion-weighted MRI (DW-MRI) to compute the apparent diffusion coefficient (ADC) due to computational simplicity and reduced post-processing times compared to the intravoxel incoherent motion (IVIM) model. The purpose of this study is to find the effect of noise level on the optimal b-values to obtain monoexponential ADC values close to the perfusion-insensitive IVIM model ADC (ADCIVIM). Methods: Respiratory triggering was applied to the echo-planar DW-MRI in 1.5T scanner with TR=∼4500 ms, TE=74 ms, eight b-values of 0–1000 µs/µm 2 , pixel size=1.98×1.98 mm 2 , slice thickness/gap=6 mm/1.2 mm and 7 axial slices. For one pre-treatment DW-MRI scan of each of ten subjects, DW-MRI signal intensity images with b-values of 0–2000 µs/µm 2 were synthesized on a voxel-by-voxel basis from the estimated IVIM parameters. The images were corrupted by Rician noise distribution with σ=0, 5, 10 and 15. Monoexponential ADC value was computed using b-value pairs with low b-value (blow) of 0–500 µs/µm 2 and high b-value (bhigh) of 650–2000 µs/µm 2 . The square root of the mean of squared error percentage (RMSE) of the ADC value relative to the corresponding reference-standard ADCIVIM for the tumor volumes of the scans was computed. Results: There were wide bands of b-value sets giving small RMSE of ADC value relative to the ground-truth ADCIVIM value. The band of sets with small errors moved from high values of both blow and b high for the lowest noise level towards the lower values with the increase of the noise levels. The minimum error corresponding to the optimal sets increased with the noise level. The range of RMSE for σ=5 was approximately 5–30% whereas that for σ=15 was approximately 10–50%. Conclusion: The optimal b-value pairs for obtaining ADC values close to reference-standard values depended on the noise level and hence SNR. This work was supported by Virginia Commonwealth University Massey Cancer Center pilot project A35242 (EW). There are no conflicts of interest.

WE-G-18C-02: Estimation of Optimal B-Value Set for Obtaining Apparent Diffusion Coefficient Free From Perfusion in Non-Small Cell Lung Cancer

PURPOSE Diffusion-weighted MRI (DW-MRI) is increasingly being investigated for radiotherapy planning and response assessment. Selection of a limited number of b-values in DW-MRI is important to keep geometrical variations low and imaging time short. We investigated various b-value sets to determine an optimal set for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in nonsmall cell lung cancer. METHODS Seven patients had 27 DW-MRI scans before and during radiotherapy in a 1.5T scanner. Respiratory triggering was applied to the echo-planar DW-MRI with TR=4500ms approximately, TE=74ms, pixel size=1.98×1.98mm2 , slice thickness=4-6mm and 7 axial slices. Diffusion gradients were applied to all three axes producing traceweighted images with eight b-values of 0-1000μs/μm2 . Monoexponential model ADC values using various b-value sets were compared to ADCIVIM using all b-values. To compare the relative noise in ADC maps, intra-scan coefficient of variation (CV) of active tumor volumes was computed. RESULTS ADCIVIM, perfusion coefficient and perfusion fraction for tumor volumes were in the range of 880-1622 μm2 /s, 8119-33834 μm2 /s and 0.104-0.349, respectively. ADC values using sets of 250, 800 and 1000; 250, 650 and 1000; and 250-1000μs/μm2 only were not significantly different from ADCIVIM(p>0.05, paired t-test). Error in ADC values for 0-1000, 50-1000, 100-1000, 250-1000, 500-1000, and three b-value sets- 250, 500 and 1000; 250, 650 and 1000; and 250, 800 and 1000μs/μm2 were 15.0, 9.4, 5.6, 1.4, 11.7, 3.7, 2.0 and 0.2% relative to the reference-standard ADCIVIM, respectively. Mean intrascan CV was 20.2, 20.9, 21.9, 24.9, 32.6, 25.8, 25.4 and 24.8%, respectively, whereas that for ADCIVIM was 23.3%. CONCLUSION ADC values of two 3 b-value sets (250, 650 and 1000; and 250, 800 and 1000μs/μm2 ) approached ADCIVIM, with relative noise comparable to that of ADCIVIM. These sets may be used to obtain perfusion-insensitive ADC values in lung tumors. E. Weiss: Funding through Varian Medical Systems and Philips Oncology Systems, UpToDate royalties. G. Hugo: NIH R01CA166119, P01 CA116602, NHMRC Project Grant.