Radiology: Quantitative MRI may assess ovarian cancer treatment response

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Apparent diffusion coefficient (ADC) histograms derived from quantitative diffusion-weighted MRI helped predict chemotherapy response in patients with metastatic ovarian or primary peritoneal cancer, according to a study published in this month's issue of Radiology.

Early assessment of response to chemotherapy in ovarian cancer patients is desirable as patients tend to respond less favorably to second- and third-line regimens. However, current mechanisms of monitoring response to chemotherapy--biochemical and imaging criteria--provide limited predictive value. An improved method could allow patients to avoid toxicity of inefficient agents, according to Stavroula Kyriazi, MD, from the Cancer Research-UK and EPSRC Cancer Imaging Centre in Surrey, England, and colleagues.

Kyriazi and colleagues sought to examine the utility of ADC histogram analysis in the assessment of chemotherapy response of patients with metastatic ovarian cancer. The researchers recruited 59 patients from November 2008 to September 2010.

MR imaging was performed at baseline and after one and three cycles of a six-cycle chemotherapy regimen. Software was used to calculate ADCs, segment regions of interest and register image data. The researchers measured CA-125 levels and completed CT exams after the third and sixth cycles.

The researchers also assessed reproducibility of the exam by randomly selecting 10 patients to undergo a repeat study. They determined that the MR results were reproducible.

The histogram assessment showed a significant increase in all ADC parameters, except for skew and kurtosis after the first chemotherapy cycle in responders, whereas nonresponders had no significant changes. Responders maintained the significant increase in ADC parameters after the third cycle, except for skew and kurtosis, which decreased significantly. There were no changes among nonresponders.

The study demonstrated the predictive value of ADC histogram parameters, irrespective of histologic grade and primary versus relapsed disease status, according to the authors. “Response was associated with an early and sustained increase of ADCs and a later decrease of skew and kurtosis on cumulative histograms, reflecting total disease burden,” they wrote.

Kyriazi and colleagues said that ADC histogram analysis could provide a useful adjunct tool for monitoring response to chemotherapy among patients with advanced ovarian or primary peritoneal cancer.