Jong-Ryool Oh

Comparison of 131I whole-body imaging, 131I SPECT/CT, and 18F-FDG PET/CT in the detection of metastatic thyroid cancer

PurposeThe aim of this study was to compare 131I whole-body scintigraphy (WBS), WBS with 131I single photon emission computed tomography/computed tomography (SPECT/CT), and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of distant metastases of differentiated thyroid cancer (DTC).MethodsA total of 140 patients with 258 foci of suspected distant metastases were evaluated. 131I WBS, 131I SPECT/CT, and 18F-FDG PET/CT images were interpreted separately. The final diagnosis was obtained from histopathologic study, serum thyroglobulin level, other imaging modalities, and/or clinical follow-up.ResultsOf the 140 patients with 258 foci, 46 patients with 166 foci were diagnosed as positive for distant metastasis. The sensitivity, specificity, and diagnostic accuracy of each imaging modality were 65, 55, and 59%, respectively, for 131I WBS; 65, 95, and 85% for 131I SPECT/CT, respectively; and 61, 98, and 86%, respectively, for 18F-FDG PET/CT in patient-based analyses. Lesion-based analyses demonstrated that both SPECT/CT and PET/CT were superior to WBS (p<0.001) in all patient groups. SPECT/CT was superior to WBS and PET/CT (p<0.001) in patients who received a single challenge of radioiodine therapy, whereas PET/CT was superior to WBS (p=0.005) and SPECT/CT (p=0.013) in patients who received multiple challenges.ConclusionBoth SPECT/CT and PET/CT demonstrated high diagnostic performance in detecting metastatic thyroid cancer. SPECT/CT was highly accurate in patients who underwent a single challenge of radioiodine therapy. In contrast, 18F-FDG PET/CT presented the highest diagnostic performance in patients who underwent multiple challenges of radioiodine therapy.

Impact of Medication Discontinuation on Increased Intestinal FDG Accumulation in Diabetic Patients Treated With Metformin

OBJECTIVE We evaluated the impact of stopping medication for 2 days on reductions in the high intestinal FDG uptake induced by metformin. SUBJECTS AND METHODS One hundred thirty-eight diabetic patients were divided into two groups: one in which the antihyperglycemic drug regimen included metformin (group A; n = 107) and one in which the regimen did not include metformin (group B; n = 31). Fifty-two patients without diabetes mellitus served as the control group (group C). Group A was divided into two subgroups: 77 patients (group A1) were taking metformin at the time of FDG PET/CT scans, whereas the remaining 30 patients (group A2) were asked to stop taking metformin for 2 days before PET/CT scans. In addition, 10 diabetic patients underwent two consecutive PET/CT scans before and after the discontinuation of metformin. The intestinal FDG uptake and blood glucose levels were compared among the four groups, as well as before and after the discontinuation of metformin. RESULTS The high intestinal FDG uptake in group A1 was significantly reduced after the discontinuation of metformin (p < 0.001 vs group A2); thus, there were no significant differences among group A2, group B, and group C (p = 0.581-0.872). There were also no statistically significant differences in the blood glucose levels among the three groups of diabetic patients (p > 0.9). In 10 patients who underwent serial PET/CT scans, mean intestinal FDG uptake decreased by 64% without significant changes in the blood glucose level. Hidden colorectal malignancies were revealed in two patients after the discontinuation of medication. CONCLUSION The discontinuation of metformin for 2 days is feasible for reducing the high intestinal FDG uptake induced by metformin.

A stepwise approach using metabolic volume and SUVmax to differentiate malignancy and dysplasia from benign colonic uptakes on 18F-FDG PET/CT.

PURPOSE The purpose of this study was to suggest a new diagnostic strategy using metabolic volume (MV) and maximum standardized uptake value (SUVmax) to differentiate malignancy and dysplasia from benign colonic 2-deoxy-2-18F-fluoro-D-glucose (FDG) uptakes. MATERIALS AND METHODS From records of 21,317 consecutive FDG positron emission tomography/computed tomography (PET/CT) scans at 2 centers, 102 focal colonic lesions in 99 patients investigated by colonoscopy and histopathologic examination were eligible for this retrospective study. SUVmax and MV were compared according to colonoscopic and histopathologic results. Firstly, dysplasia was separated from malignancy and benign lesions. Secondly, malignancy and benign lesions were separated from each other. The better parameters of each step were determined, and a diagnostic strategy was developed from their combination. RESULTS A total of 102 incidental colonic FDG uptakes were revealed as 32 malignancies, 43 dysplasias, and 27 benign lesions. MV better differentiated dysplasia from malignancy and benign lesions (cutoff value, ≤3.14 cm3; area under the receiver-operating characteristic curve [AUC] = 0.947), and SUVmax better differentiated malignancy from benign lesions (cutoff value, >9.1; AUC = 0.934). Overall, the stepwise algorithm using MV and SUVmax (AUC = 0.886) was superior to single measurements of SUVmax (AUC = 0.750) and MV (AUC = 0.714) for differentiating malignancy and dysplasia from benign lesions; sensitivity: 92%, specificity: 85%, accuracy: 90%, positive predictive value: 94%, negative predictive value: 79%. CONCLUSIONS The stepwise approach using MV and SUVmax was able to differentiate malignancy and dysplasia from benign colonic FDG uptakes on PET/CT. Colonic FDG uptake with MV ≤3.14 cm3 had a high probability of dysplasia. MV >3.14 cm3 and SUVmax >9.1 indicated malignancy, whereas MV >3.14 cm3 and SUVmax ≤9.1 indicated benign lesions.

The Clinical Usefulness of (18)F-FDG PET/CT in Patients with Systemic Autoimmune Disease.

PurposeIndividuals with systemic autoimmune disease have an increased susceptibility to both inflammation and malignancy. The aim of this study was to evaluate the clinical usefulness of 18F-FDG PET/CT in patients with systemic autoimmune disease.MethodsForty patients diagnosed with systemic autoimmune disease were enrolled. Diagnostic accuracy of FDG PET/CT for detecting malignancy was assessed. FDG PET/CT findings, including maximum standardized uptake (SUVmax) of lymphadenopathy (LAP), liver, bone marrow, spleen, joint and muscles, were considered for the characterization of LAPs.ResultsFDG PET/CT could detect metabolically activated lesions in 36 out of 40 patients (90%) including inflammatory lesions in 28 out of 32 patients (88%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG PET/CT for the detection of malignancy were 100, 67, 70, 25, and 100%, respectively. Multiple LAPs were found in 25 of 40 patients (63%), and comprised three malignancies, four cases of tuberculosis, and 18 reactive changes. A SUVmax ratio of bone marrow to liver below 0.78 could distinguish malignancy from tuberculosis + reactive change (AUC = 1.000, sensitivity: 100%, specificity: 100%). The SUVmax ratio of spleen to liver in the reactive group was also significantly higher than that in the malignancy group (P = 0.014). SUVmax of LAP in the TB group was significantly higher than that in the reactive group (P = 0.040).ConclusionsPET/CT is useful in detecting and differentiating inflammation and malignancy in patients with systemic autoimmune disease. Frequent false-positive interpretations can be minimized by consideration of FDG uptake in bone marrow and spleen.

Herniation pit mimicking osseous metastasis on 18F-FDG PET/CT in patient with lung cancer.

Herniation pits are small subcortical osseous defects located typically at the proximal anterosuperior quadrant of the femoral neck that are most frequently seen in the young, athletic adult population. We report a case with herniation pit showing focal 18F-FDG uptake on PET/CT images mimicking osseous metastasis in a 69-year-old patient with lung cancer.