Bone scintigraphy

All 4180 patients received ^99mTc-MDP (FUJIFILM Toyama Chemical Co. Ltd.) for examing suspected bone metastasis. All patients received 555 to 740 MBq of ^99mTc-MDP intravenously. Images were acquired 3 hours after radiotracer admin-istration (9). Whole body images were acquired at a scan speed of 16 cm/minute using low energy high resolution collimators (DISCOVERY™ NM, GE). We performed planar images and also performed SPECT images centered on the thorax if clinically indicated in some patients.

The intensity of the myocardial uptake was graded based on a visual scale ranging from 0 to 3 points. Score 0 indicates the absence of uptake. Score 1 defined uptake less than that of bone (referred to as the adjacent rib). Uptake similar to that of bone was classified score 2. Score 3 was defined as uptake greater than that of reference bone (Figure 1A). Positive myocardial uptake included a visual score 2 or 3. The distribution of the uptake in myocardium was defined as focal uptake, diffuse uptake, uptake in a segmental ventricular wall uptake, diffuse ventricular uptake, or diffuse biventricular uptake. Cardiac uptake was also assessed with quantitative analysis by drawing a region of interest (ROI) over the heart corrected for contralateral counts and calculating a heart-to-contralateral ratio (H/CL) (Figure 1B) (10).

Semi-quantitative and quantitative interpretation: ^99mTc-MDP uptake of myo-cardium.

A: The intensity of the myocardial uptake was graded according to a visual scale ranging from 0 to 3 points, in which the absence of uptake was assigned a score of 0 points; uptake less than that of bone (referred to as the adjacent rib), 1 point; uptake similar to that of bone, 2 points; and uptake greater than that of bone, 3 points.

B: Heart-to-contralateral ratio was calculated by drawing a region of interest over the heart, copying and mirroring it to the contralateral chest and calculating the ratio of heart ROI mean counts to contralateral ROI mean counts.