• Hiroo Kajihara, Yoshiko Hayashida, Ryuji Murakami, Kazuhiro Katahira, Ryuichi Nishimura, Yasuyuki Hamada, Kousuke Kitani, Mitsuhiko Kitaoka, Yasuko Suzuki, Mika Kitajima, Toshinori Hirai, Shoji Morishita, Kazuo Awai, and Yasuyuki Yamashita.
• Department of Radiology, Kumamoto Chuo Hospital, Japan.
• Int. J. Radiat. Oncol. Biol. Phys. 2009 Jun 1; 74 (2): 399-403.

PurposeAdvances in high-precision radiation therapy techniques for patients with prostate cancer permit selective escalation of the radiation dose delivered to the dominant intraprostatic lesion and improve the therapeutic ratio. We evaluated the value of diffusion-weighted imaging (DWI) for dominant intraprostatic lesion assessment.Methods And MaterialsThe study population consisted of 23 patients with early prostate cancer. Before undergoing total prostatectomy, they were evaluated by means of magnetic resonance imaging, including DWI. T2-weighted imaging (T2WI) with and without DWI were retrospectively assessed by six independent observers. Imaging findings were compared with pathologic results from whole prostate specimens on a lesion-by-lesion basis.ResultsPathologic study identified 43 lesions in 23 patients. On magnetic resonance imaging, the six observers correctly identified 11-22 of 43 lesions (sensitivity, 26-51%) on T2WI alone and 20-31 (sensitivity, 47-72%) on T2WI plus DWI. Positive predictive values were 42-73% on T2WI alone and 58-80% on T2WI plus DWI. For all observers, detection was higher on combined T2WI and DWI than on T2WI alone.ConclusionBecause the addition of DWI to T2WI improves the detectability of prostate cancer, DWI may offer a promising new approach for radiation therapy planning.

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