An early increase of ADCs and later decrease of skew and kurtosis characterize chemotherapy response. Quantitative DW MR imaging can aid in early monitoring of treatment efficacy in patients with advanced ovarian cancer.

FRCP, FRCP Nandita M. deSouza, MD, FRCP, FRCR Purpose:To determine the feasibility of whole-body diffusionweighted (DW) magnetic resonance (MR) imaging for assessment of treatment response in myeloma. Materials and Methods:This prospective single-institution study was HIPAAcompliant with local research ethics committee approval. Written informed consent was obtained from each subject. Eight healthy volunteers (cohort 1a) and seven myeloma patients (cohort 1b) were imaged twice to assess repeatability of quantitative apparent diffusion coefficient (ADC) estimates. Thirty-four additional myeloma patients (cohort 2) underwent whole-body DW imaging before treatment; 26 completed a posttreatment imaging. Wholebody DW data were compared before and after treatment by using qualitative (ie, observer scores) and quantitative (ie, whole-body segmentation of marrow ADC) methods. Serum paraproteins and/or light chains or bone marrow biopsy defined response. Results:Whole-body DW imaging scores were significantly different between observers (P , .001), but change in scores between observers after treatment was not (P = .49). Sensitivity and specificity for detecting response according to observer scores were 86% (18 of 21 patients) and 80% (4 of 5 patients) for both observers. ADC measurement was repeatable: mean coefficient of variation was 3.8% in healthy volunteers and 2.8% in myeloma patients. Pretreatment ADC in cohort 2 was significantly different from that in cohort 1a (P = .03), but not from that in cohort 1b (P = .2). Mean ADC increased in 95% (19 of 20) of responding patients and decreased in all (five of five) nonresponders (P = .002). A 3.3% increase in ADC helped identify response with 90% sensitivity and 100% specificity; an 8% increase (greater than repeatability of cohort 1b) resulted in 70% sensitivity and 100% specificity. There was a significant negative correlation between change in ADC and change in laboratory markers of response (r = 20.614; P = .001). Conclusion:Preliminary work demonstrates whole-body DW imaging is a repeatable, quantifiable technique for assessment of treatment response in myeloma.q RSNA, 2014 1

Median ADC is lower in poorly compared with well or moderately differentiated tumors, while lower histogram-positive skew in adenocarcinoma compared with squamous cell carcinoma is likely to reflect the glandular content of adenocarcinoma.

ADC of active myeloma is significantly higher than marrow in remission; the direction of ADC changes on treatment is dependent on the timing of measurements and is influenced by changes in marrow fat.

• ADC values from fibroglandular breast tissue are measured reproducibly by multiple observers. • Mean ADC values were significantly lower in postmenopausal than premenopausal breast tissue. • Mean ADC values did not vary significantly with menstrual cycle. • Low postmenopausal ADC values may hinder tumour detection on DW-MRI.

Mean ADC is not an appropriate measure of response in bone metastases. The heterogeneity of changes in ADC is likely to be related to the composition of bone marrow with changes that have opposing effects on ADC.

An ADC derived from DWI is a useful adjunct to T2-weighted MRI for detecting local tumor recurrence larger than 0.4 cm(2) within the prostate.

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