Naoki Makino

Comparison of 18F-FDG PET and Bone Scintigraphy in Detection of Bone Metastases of Thyroid Cancer

We compared the efficacies of 18F-FDG PET and 99mTc-bone scintigraphy for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC). Methods: We examined 47 patients (32 women, 15 men; mean age ± SD, 57.0 ± 10.7 y) with DTC who had undergone total thyroidectomy and were hospitalized to be given 131I therapy. All patients underwent both whole-body 18F-FDG PET and 99mTc-bone scintigraphy. The skeletal system was classified into 11 anatomic segments and assessed for the presence of bone metastases. Bone metastases were verified either when positive findings were obtained on >2 imaging modalities—201Tl scintigraphy, 131I scintigraphy, and CT—or when MRI findings were positive if vertebral MRI was performed. Results: Bone metastases were confirmed in 59 of 517 (11%) segments in 18 (38%) of the 47 study patients. The sensitivities (visualization rate) for bone metastases on a segment basis using 18F-FDG PET and 99mTc-bone scintigraphy were 50 of 59 (84.7%) and 46 of 59 (78.0%), respectively; the difference between these values was not statistically significant. There were only 2 (0.4%) false-positive cases in a total of 451 bone segments without bone metastases when examined by 18F-FDG PET, whereas 39 (8.6%) were false-positive when examined by 99mTc-bone scintigraphy. Therefore, the specificities of 18F-FDG PET and 99mTc-bone scintigraphy were 449 of 451 (99.6%) and 412 of 451 (91.4%), respectively; the difference between these values was statistically significant (P < 0.001). The overall accuracies of 18F-FDG PET and 99mTc-bone scintigraphy were 499 of 510 (97.8%) and 458 of 510 (89.8%), respectively; the difference between these was also statistically significant (P < 0.001). Conclusion: The specificity and the overall accuracy of 18F-FDG PET for the diagnosis of bone metastases in patients with DTC are higher than those of 99mTc-bone scintigraphy, whereas the difference in the sensitivities of both modalities is not statistically significant. In comparison with 99mTc-bone scintigraphy, 18F-FDG PET is superior because of its lower incidence of false-positive results in the detection of bone metastases of DTC.

Solitary pulmonary nodules Optimal slice thickness of high-resolution CT in differentiating malignant from benign

The purpose of this study was to determine an optimal slice thickness that was efficient in differentiating malignant from benign solitary pulmonary nodules (SPNs) on high-resolution computed tomography (HRCT) images. For a total of 92 SPNs, four radiologist indicated their confidence level for the malignant or benign SPN on the CT images presented in 1-, 3-, and 5-mm slice thickness. HRCT could be used to differentiate more accurately the malignant nodules from the benign ones using 1-mm-thick sections than 3- or 5-mm-thick sections.

Videotaped helical CT images for lung cancer screening.

PURPOSE The goal of this work was to determine a radiologists ability to detect solitary pulmonary nodules on helical CT using both video (cine) viewing and film-based viewing. METHOD Sixty-five chest helical CT studies were reviewed. Six radiologists searched for 40 lung nodules on CT images presented in three formats. Film-based viewing of images at 10 and 5 mm increments was performed with a light box. Video viewing of the same examinations was performed in 5 mm increments at 2 frames/s. The area under the receiver operating characteristic curve (Az) measured the observers ability to detect nodules. RESULTS The Az was 0.948 for the video viewing, 0.844 for 5 mm increment film-based viewing, and 0.879 for 10 mm increment film-based viewing. There were no statistically significant differences. CONCLUSION Lung nodules can be detected with similar detection rates when viewing conventional film or videotaped helical CT images. Videotaped images incur a lower cost, an important consideration in mass screening for lung cancer.

Role of Fast Data Acquisition Method with Tc-99m HMPAO Brain SPECT in Patients with Acute Stroke:

The fast data acquisition method for Tc-99m hexamethyl-propyleneamineoxime (Tc-99m HMPAO) brain SPECT was used in two patients with acute stroke 5 and 8 hours after the event. In one patient Tc-99m HMPAO fast SPECT showed perfusion defects before the same was manifested on CT. In the other patient, Tc-99m HMPAO fast SPECT showed larger defects than the edema seen on CT. The Tc-99m HMPAO fast SPECT might be feasible for the evaluation of acute stroke patients. Since the time required for fast SPECT is much shorter than usual SPECT, it appears to be more suitable for some patients with acute stroke who are brought to the hospital in a very critical condition.