Differentiation of FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer with dual-time point F-18-fluorodeoxy-glucose PET/CT scan.

OBJECTIVE: To evaluate the ability of dual-time point F-18-fluorodeoxy-glucose (FDG) PET/CT scans to differentiate FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer. METHODS: A total of 64 FDG-avid recurrent lesions (local tumor recurrence or lymph node metastases) in 52 patients and 38 FDG-avid compromised benign lesions after surgery in 37 patients were included in the study. FDG PET/CT study was performed at 60 and 120 min after intravenous injection of 3.5 MBq/kg FDG. The maximum SUV (SUVmax) on the early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis. RESULTS: The average early SUVmax, delayed SUVmax and DeltaSUVmax% were 4.9 +/- 2.6, 6.0 +/- 3.6 and 18.2% +/- 18.8 in FDG-avid recurrent lesions, and 2.1 +/- 0.8, 1.8 +/- 1.0 and -17.8% +/- 21.3 in FDG-avid benign lesions, respectively. Delayed SUVmax was significantly increased compared with early SUVmax in recurrent lesions (P < 0.0001), while it was decreased in benign lesions (P < 0.0001). All the three parameters in recurrent lesions were significantly higher than those in benign lesions (P < 0.0001). The highest diagnostic accuracy of the differentiation was achieved by the combined use of the optimal parameter of delayed SUVmax > 2.5 and %DeltaSUVmax > 0%, with a sensitivity of 90.6%, specificity of 81.5%, accuracy of 87.2%, NPV of 89.2%, and PPV of 83.7%, which were better than the respective values obtained with the use of delayed SUVmax > 2.5 alone or %DeltaSUVmax > 0% alone (P < 0.005 and P < 0.05, respectively), and the use of the traditional parameter of early SUVmax > 2.5 (P < 0.005). CONCLUSIONS: This approach with SUVmax estimation appears to improve the differentiation between FDG-avid loco-regional recurrent of breast cancer and compromised benign lesions after surgery, since delayed scanning significantly enhances the difference in FDG uptake between these lesions.

Role of high-resolution CT in the diagnosis of small pulmonary nodules coexisting with potentially operable lung cancer.

PURPOSE: The purpose of this study was to evaluate whether high-resolution CT (HRCT) could facilitate the preoperative diagnosis of one or two small nodules of 1 cm or less coexisting with a lung cancer, i.e., coexisting small nodule. MATERIALS AND METHODS: This study included 27 coexisting small nodules in 24 potentially operable lung cancer patients. An observer study was performed by five radiologists. The observer performances in differentiating malignant from benign coexisting small nodules were evaluated on conventional CT and HRCT using receiver operating characteristic (ROC) analysis. RESULTS: The area under the ROC curve of five observers was 0.731 on HRCT and 0.578 on conventional CT in the differential diagnosis of coexisting small nodules. A significant diagnostic improvement was found on HRCT (p=0.031). This was especially evident for nodules of ground-glass attenuation (p=0.005). CONCLUSION: HRCT plays an important role in determining the treatment of potentially operable lung cancer patients with coexisting small nodules.

F-18 FDG PET/CT monitoring of radiation therapeutic effect in hepatic epithelioid hemangioendothelioma.

We report the F-18 FDG PET/CT findings in a 59-year-old man with a rare hepatic tumor of malignant epithelioid hemangioendothelioma, who was treated with radiotherapy (RT). This patient had multifocal discrete hepatic tumors, and PET/CT images showed intense FDG uptake in these nodules, regardless of poor enhancement on contrast-enhanced computed tomography. Seven months after RT to the 2 relatively large nodules, the intense FDG uptake disappeared in these nodules, while the remaining untreated nodule showed persistently intense uptake. RT is one of the options for treatment of hepatic epithelioid hemangioendothelioma. F-18 FDG PET/computed tomography appears to be useful for monitoring the effect of RT in this neoplasm.

F-18 FDG PET-CT findings in Mikulicz disease and systemic involvement of IgG4-related lesions.

A 72-year-old woman with Mikulicz disease with pathogically proven sclerosing sialadenitis showed systemic abnormal F-18 FDG uptake in the bilateral lacrimal and submandibular glands, pancreas, abdominal aortic wall, and a retroperitoneal fibroid mass on PET/CT scan, with marked elevation of the serum IgG4 level. This case supports Mikulicz disease being included as 1 of the disorders associated with a new clinical entity of systemic IgG4-related plasmacytic syndrome. A whole-body FDG-PET/CT scan can be expected as a useful tool for detecting systemic involvement in systemic IgG4-related plasmacytic syndrome.

F-18 FDG PET/CT findings in a patient with bilateral orbital and gastric mucosa-associated lymphoid tissue lymphomas.

Orbital mucosa-associated lymphoid tissue (MALT) lymphoma is an uncommon disease, while the incidence is recently increasing. We describe the F-18 fluorodeoxyglucose positron emission tomography computerized tomography (FDG PET/CT) findings in a case of bilateral orbital MALT lymphomas with a coexisting gastric lesion. Although only the lesion in the left orbit was initially identified on MR imaging, FDG PET/CT scan unexpectedly and additionally could identify the tiny lesion of the contralateral orbit and the gastric lesion. This patient received radiotherapy to all these lesions, with a combination of rituximab monoclonal antibody therapy. The follow-up PET/CT studies at 3, 6, and 9 months and 1.5 years after treatment showed regression or disappearance of all these FDG-avid lesions. Accurate localization and staging are crucial to select an adequate treatment in MALT lymphoma at any location. This case indicates the feasibility of FDG PET/CT scan for accurate localization and staging and also for monitoring treatment in patients with orbital MALT lymphoma.

F-18 FDG PET-CT findings in a case of normal-sized ovarian cancer syndrome.

The "normal-sized ovary carcinoma syndrome (NOCS)" is defined as a clinical situation, in which diffuse metastatic malignant disease of the abdominal cavity of the female with normal-sized ovaries is noted, but no origin is assigned by preoperative or intraoperative evaluation. We report a case of ovarian serous surface papillary carcinoma with manifestation of NOCS, where F-18 FDG PET/CT scan correctly detected the site of origin, although computed tomography and magnetic resonance imaging failed to detect it. This technique may play a role to discern the site of origin of some malignancies.

Dual-time point 18F-FDG PET/CT scan for differentiation between 18F-FDG-avid non-small cell lung cancer and benign lesions.

OBJECTIVE: The aim of this study is to clarify the difference of F-18 FDG uptake kinetics between FDG-avid non-small-cell lung cancer (NSCLC) and benign lesions associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. MATERIALS AND METHODS: The materials were 76 FDG-avid solitary NSCLC in 76 patients and 57 FDG-avid solitary benign lesions associated with various etiologies in 61 patients. FDG PET/CT scan was performed at 60 and 120 min after intravenous injection of 4.4 MBq/kg F-18 FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis and evaluation of diagnostic accuracy. RESULTS: The mean +/- SD of early SUV max, delayed SUVmax and %DeltaSUVmax were 8.3 +/- 5.2, and 10.2 +/- 6.5, and 21.9% +/- 18.9 in FDG-avid NSCLC, and 3.8 +/- 3.2, 4.0 +/- 3.7, and 11.3% +/- 26.0 in FDG-avid benign lesions, respectively. Delayed SUVmax in NSCLC was significantly higher than early SUVmax (P < 0.0001); while not different in benign lesions. Percent change of SUVmax in NSCLC was also significantly higher than that in benign lesions (P < 0.01). The optimal parameter for the differentiation was delayed SUVmax > 5.5 and yielded sensitivity of 77.6%, specificity of 80.7% and accuracy of 78.9%, which provided better differentiation than the use of %DeltaSUVmax or the traditional parameter of early SUVmax > 2.5. However, 11 (19.2%) benign lesions were indistinguishable from NSCLC. CONCLUSION: Although delayed PET/CT scan enhances the difference of FDG uptake between FDG-avid NSCLC and benign lesions, and the use of delayed SUVmax > 5.5 appears to improve the differentiation of these hypermetabolic lesions compared with an early scan, careful interpretation and management for correct differentiation are still required.

Differential diagnosis between (18)F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan.

OBJECTIVE: To clarify the difference of (18)F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. METHODS: The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg (18)F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis. RESULTS: Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 +/- 5.0 vs. 5.9 +/- 3.4; P < 0.0001, and 3.0 +/- 1.3 vs. 2.8 +/- 1.0; P < 0.05, respectively). Early and delayed SUVmax and %DeltaSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %DeltaSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs. CONCLUSIONS: Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.

The probability of malignancy in small pulmonary nodules coexisting with potentially operable lung cancer detected by CT.

The aim of this study was to assess the probability of malignancy in one or two small nodules 1 cm or less coexisting with potentially operable lung cancer (coexisting small nodules). The preoperative helical CT scans of 223 patients with lung cancer were retrospectively reviewed. The probability of malignancy of coexisting small nodules was evaluated based on nodule size, location, and clinical stage of the primary lung cancers. Seventy-one coexisting small nodules were found on conventional CT in 58 (26%) of 223 patients, and 14 (6%) patients had malignant nodules. Eighteen (25%) of such nodules were malignant. The probability of malignancy was not significantly different between two groups of nodules larger and smaller than 0.5 cm ( p=0.1). The probability of malignancy of such nodules within primary tumor lobe was significantly higher than that in the other lobes ( p<0.01). Metastatic nodules were significantly fewer in clinical stage-IA patients than in the patients with the other stage ( p<0.01); however, four (57%) of seven synchronous lung cancers were located in the non-primary tumor lobes in the clinical stage-I patients. Malignant coexisting small nodules are not infrequent, and such nodules in the non-primary tumor lobes should be carefully diagnosed.