Prospective study of bone metastasis from prostate cancer: comparison between large field diffusion-weighted imaging and bone scintigraphy / 中华放射学杂志

ABSTRACT

Objective To evaluate the large field diffusion weighted imaging (DWI) (from head vertex to lower leg) in detection of bone metastases from prostate cancer. Methods One hundred and sixty-six consecutive patients who were suspected of prostate cancer received pelvic MRI and large field diffusion weighted imaging examination. Forty-nine of them underwent bone scintigraphy within one month of the examination of large field DWI. The images were double-blindly evaluated without the knowledge of the pathology result. Conventional MR T1 and fat saturation T2 weighted images were taken as standard for the diagnosis of bone metastasis. The sensitivity, specificity, and area under curve between large field DWI and bone scintigraphy were compared with McNemar test. Five patients with bone metastases exceeding 10 per patient were excluded in the lesion-by-lesion analysis. Results Ten of the 49 patients were diagnosed as bone metastases. The diagnosis of bone metastasis were made in 15 patients by large field DWI and in 17 patients by bone scintigraphy. With patient number as study units (n =49) , the diagnostic sensitivity of bone metastases with large field DWI and bone metastases were both 100% (10/10), and specificity were 87. 2% (34/39) vs. 82. 1% (32/39), respectively. ROC study showed the area under curve (AUC) of large field DWI and bone scintigraphy were 0. 936 vs. 0. 910, respectively. Totally 68 abnormal foci were identified from large field DWI and/or bone scintigraphy in 44 patients (while 5 patients with bone metastases exceeding 10 foci per patient were excluded ), 20 of them were diagnosed as foci of bone metastasis. The diagnosis of bone metastases was made in 23 foci by large field DWI and in 34 by bone seintigraphy. With lesion numbers as study units ( n = 68), the diagnostic sensitivity of large field DWI and bone scintigraphy were both 90. 0% ( 18/20), and specificity were 89.6% (43/48) vs. 66. 7% (32/48) , respectively. ROC study showed the area under curve of large field DWI and bone scintigraphy were 0. 898 vs. 0. 783, respectively. The difference of specificity between large field DWI and bone scintigraphy showed statistical significant difference (P < 0. 01 ). The AUC between large field DWI and bone scintigraphy showed statistical significant difference (P < 0. 05). Conclusion Large field DWI may allow us to screen for bone metastasis in patients with prostate cancer, and its diagnostic specificity and accuracy may be higher than that of bone scintigraphy.