3D SPECT/CT fusion using image data projection of bone SPECT onto 3D volume-rendered CT images: feasibility and clinical impact in the diagnosis of bone metastasis.

PURPOSE: We developed a method of image data projection of bone SPECT into 3D volume-rendered CT images for 3D SPECT/CT fusion. The aims of our study were to evaluate its feasibility and clinical usefulness. METHODS: Whole-body bone scintigraphy (WB) and SPECT/CT scans were performed in 318 cancer patients using a dedicated SPECT/CT systems. Volume data of bone SPECT and CT were fused to obtain 2D SPECT/CT images. To generate our 3D SPECT/CT images, colored voxel data of bone SPECT were projected onto the corresponding location of the volume-rendered CT data after a semi-automatic bone extraction. Then, the resultant 3D images were blended with conventional volume-rendered CT images, allowing to grasp the three-dimensional relationship between bone metabolism and anatomy. WB and SPECT (WB + SPECT), 2D SPECT/CT fusion, and 3D SPECT/CT fusion were evaluated by two independent reviewers in the diagnosis of bone metastasis. The inter-observer variability and diagnostic accuracy in these three image sets were investigated using a four-point diagnostic scale. RESULTS: Increased bone metabolism was found in 744 metastatic sites and 1002 benign changes. On a per-lesion basis, inter-observer agreements in the diagnosis of bone metastasis were 0.72 for WB + SPECT, 0.90 for 2D SPECT/CT, and 0.89 for 3D SPECT/CT. Receiver operating characteristic analyses for the diagnostic accuracy of bone metastasis showed that WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT had an area under the curve of 0.800, 0.983, and 0.983 for reader 1, 0.865, 0.992, and 0.993 for reader 2, respectively (WB + SPECT vs. 2D or 3D SPECT/CT, p < 0.001; 2D vs. 3D SPECT/CT, n.s.). The durations of interpretation of WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT images were 241 ± 75, 225 ± 73, and 182 ± 71 s for reader 1 and 207 ± 72, 190 ± 73, and 179 ± 73 s for reader 2, respectively. As a result, it took shorter time to read 3D SPECT/CT images than 2D SPECT/CT (p < 0.0001) or WB + SPECT images (p < 0.0001). CONCLUSIONS: 3D SPECT/CT fusion offers comparable diagnostic accuracy to 2D SPECT/CT fusion. The visual effect of 3D SPECT/CT fusion facilitates reduction of reading time compared to 2D SPECT/CT fusion.

Evaluation of patients with clinically detected recurrence of rectal carcinoma: Current practice patterns of colorectal surgeons.

The optimal evaluation of patients with clinically suspected recurrence of rectal carcinoma following initial treatment has yet to be determined. We documented the intensity of the extent-of-disease workup conducted by colorectal surgeons when their patients with rectal carcinoma develop clinical evidence of metastases. A custom-designed questionnaire was mailed to all 1,795 members of the American Society of Colon and Rectal Surgeons. Subjects were asked which laboratory tests and imaging studies they would order for one of their own generally healthy patients with a suspicious abnormality found during surveillance testing. The tests most frequently recommended were computed tomography and serum carcinoembryonic antigen level. Few tests were recommended by >90% of respondents. There is no consensus among experts in this common situation.

How initial tumor stage affects rectal cancer patient follow-up.

Many believe that follow-up testing for rectal carcinoma patients after primary curative-intent therapy should be rather intensive for high-stage lesions and less intensive for low-stage lesions. We recently carried out a survey of the American Society of Colon and Rectal Surgeons (ASCRS) to quantify the strategies they use after primary treatment for their own patients. Considerable variability in surveillance exists. Here we report how initial TNM stage affects follow-up intensity. We devised vignettes succinctly describing otherwise healthy patients with rectal carcinoma (stages I-III). We mailed a questionnaire based on the vignettes to the 1,795 ASCRS members. Responses deemed evaluable were entered into a computer database. The effect of TNM stage on follow-up intensity for patients with stage I, II, or III rectal carcinoma treated with radical surgery was assessed by repeated-measures ANOVA. The surveillance modality most frequently utilized was the office visit. In year 1 following surgery for patients with stage I lesions, 3.8+/-2.7 office visits (mean +/- SD) were recommended, decreasing to 1.5+/-1.0 in year 5. For patients with stage III lesions treated with radical surgery +/- adjuvant therapy, 4.0+/-2.8 office visits were recommended in year 1, decreasing to 1.7+/-1.2 in year 5. Similar results were generated for all commonly used surveillance modalities. The intensity of follow-up after curative-intent treatment for rectal carcinoma varies minimally across TNM stages. This suggests that a controlled trial comparing high-intensity versus low-intensity follow-up testing could be carried out without stratification by TNM stage.

Practice patterns in rectal cancer patient follow-up are unaffected by surgeon age.

BACKGROUND: Surveillance strategies for of rectal cancer patients after potentially curative treatment vary significantly. We investigated whether the age of the surgeon affects choice of surveillance strategy. METHODS: We developed vignettes depicting 4 generally healthy patients with rectal cancer of various stages who received various treatments. A questionnaire based on these vignettes was sent to the 1795 members of the American Society of Colon and Rectal Surgeons (ASCRS). RESULTS: There was no significant relationship between surgeon age and follow-up test-ordering schedules for any of the 4 vignettes. There was no significant relationship between surgeon age and 10 of the 11 possible motivating factors. CONCLUSIONS: Follow-up testing among ASCRS surgeons does not vary significantly among surgeons trained at various times. The motivation for follow-up testing is nearly uniform among age strata.

Geographic variation in follow-up after rectal cancer surgery.

Most patients with rectal cancer are treated with curative-intent surgery; adjuvant chemotherapy and radiation are often used as well. A recent survey of members of the American Society of Colon and Rectal Surgeons (ASCRS) revealed considerable variation in surveillance intensity after primary treatment. We evaluated whether geographic factors may be responsible for the observed variation. Vignettes of hypothetical patients and a questionnaire based on the vignettes were mailed to the 1782 members of ASCRS. Repeated-measures analysis of variance was used to compare practice patterns, as revealed by the responses, according to US Census Regions and Divisions, Metropolitan Statistical Areas (MSA), and state-specific managed care organization (MCO) penetration rates. There was significant variation in surveillance intensity according to the US Census Region and Division in which the surgeon practiced. Non-US respondents employed CT of the abdomen and pelvis, chest radiography, and colonoscopy significantly more often than US respondents. MSA was not a significant source of variation. Surveillance patterns varied significantly by MCO penetration rate for office visits and CT of the abdomen and pelvis but not for other modalities. The US Census Region and Division in which the surgeon practices have a significant effect on surveillance intensity following completion of primary curative-intent therapy for rectal cancer patients. The MSA in which the surgeon practices does not affect surveillance intensity significantly and MCO penetration rate affects follow-up intensity minimally. All significant differences are clinically rather modest, however. These data should be useful in the design of controlled trials on this topic.

Patient surveillance after curative-intent surgery for rectal cancer.

The follow-up of patients with rectal cancer after potentially curative resection has significant financial and clinical implications for patients and society. The ideal regimen for monitoring patients is unknown. We evaluated the self-reported practice patterns of a large, diverse group of experts. There is little information available describing the actual practice of clinicians who perform potentially curative surgery on rectal cancer patients and follow them after recovery. The 1795 members of the American Society of Colon and Rectal Surgeons were asked, via a detailed questionnaire, how often they request 14 discrete follow-up modalities in their patients treated for cure with TNM stage I, II, or III rectal cancer over the first five post-treatment years. 566/1782 (32%) responded and 347 of the respondents (61%) provided evaluable data. Members of the American Society of Colon and Rectal Surgeons typically follow their own patients postoperatively rather than sending them back to their referral source. Office visit and serum CEA level are the most frequently requested items for each of the first five postoperative years. Endoscopy and imaging tests are also used regularly. Considerable variation exists among these highly experienced, highly credentialed experts. The surveillance strategies reported here rely most heavily on relatively simple and inexpensive tests. Endoscopy is employed frequently; imaging tests are employed less often. The observed variation in the intensity of postoperative monitoring is of concern.