Relationship between multi-pool model-based chemical exchange saturation transfer imaging, intravoxel incoherent motion MRI, and 11C-methionine uptake on PET/CT in patients with gliomas.

PURPOSE: Magnetization transfer ratio asymmetry (MTRasym) analysis is used for chemical exchange saturation transfer (CEST) in patients with gliomas; however, this approach has limitations. CEST imaging using a multi-pool model (MPM) may allow a more detailed assessment of gliomas; however, its mechanism remains unknown. This study aimed to assess the relationship between CEST imaging by MPM, intravoxel incoherent motion (IVIM), and 11C-methionine (11C-MET) uptake on positron emission tomography/computed tomography (PET/CT) to clarify the clinical significance of CEST imaging using MPM in gliomas. METHODS: This retrospective study included 17 patients with gliomas who underwent 11C-MET PET/CT at our institution between January 2020 and January 2022. Two-dimensional axial CEST imaging was conducted using single-shot fast-spin echo acquisition at 3 T. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), f, MTRasym (3.5 ppm), parameters of MPM-based CEST imaging, and tumor-to-contralateral normal brain tissue (T/N) ratio were calculated using a region-of-interest analysis. Shapiro-Wilk test, weighted kappa coefficient, and Spearman's rank correlation coefficients were used for statistical analysis. RESULTS: Significant correlations were found between APT_T1 and T/N ratio (ρ = 0.87, p < 0.001), APT_T2 and T/N ratio (ρ = 0.47, p < 0.05), MTRasym and T/N ratio (ρ = 0.55, p < 0.01), and T2/T1 and T/N ratio (ρ = -0.36, p < 0.05). Furthermore, significant correlations were observed between APT_T1 and ADC (ρ = -0.67, p < 0.001), APT_T1 and D (ρ = -0.70, p < 0.001), APT_T2 and D* (ρ = -0.45, p < 0.05), and T2/T1 and D (ρ = 0.39, p < 0.05). CONCLUSION: These preliminary findings indicate that MPM-based CEST imaging parameters correlate with IVIM and 11C-MET uptake on PET/CT in patients with gliomas. In particular, the new parameter APT_T1 correlated more strongly with 11C-MET uptake compared to the traditional CEST parameter MTRasym.

11C-PiB PET/CT in nasopharyngeal amyloidosis associated with multiple myeloma.

We present an unusual case of nasopharyngeal amyloidosis associated with multiple myeloma. A 63-year-old woman presented with 2 months' history of epistaxis and dentalgia 3 years after being diagnosed with multiple myeloma. CT and C-Pittsburgh compound B (PiB) PET images demonstrated that the intense C-PiB uptake corresponded to the nasal, paranasal, and palatal area matching the CT mass lesion. Histopathologic examination confirmed amyloidosis.

Detection of small fenestral otosclerotic lesions by high-resolution computed tomography using multiplanar reconstruction.

OBJECTIVE: The aim of this study was to assess the value of multislice computed tomography (MSCT) using multiplanar reconstruction (MPR) to detect the small fenestral lesions in patients with otosclerosis. METHODS: MSCT with MPR imaging was used to evaluate 27 ears of 17 patients with otosclerosis (3 male and 14 females) ranging in age from 33 to 69 years with a mean of 49.8 year. MSCT imaging was performed using Aquilion®. Axial spiral scans with a 0.5-mm slice thickness were obtained. The acquired high-resolution data were transferred to a workstation (ALATO VIEW). MPR images were created in the planes parallel to the stapedial crus and then analyzed on the monitor screen by two radiologists (Y.T. and N.K.). RESULTS: MPR images showed abnormal findings in 26 of 27 ears with otosclerosis (96%), whereas axial images showed abnormal findings in only 15 of 27 ears (56%). The similar classification between both images was shown only in 9 of 27 ears (33%). In 16 ears (67%) axial images under-evaluated the lesions compared with MPR images. MPR images detected smaller foci than axial images. Air-bone gap at 0.5-4kHz tended to increase dependently on the extension of fenestral lesions evaluated by MPR images. CONCLUSION: MPR images detected fenestral lesions in otosclerosis more frequently and more precisely than axial images. The extent of fenestral lesions observed on MPR images tends to be related to the degree of conductive hearing loss.

CT assessment of subtypes of pulmonary emphysema in females.

We performed a retrospective study examining the prevalence and subtypes of pulmonary emphysema (PE) identified by computed tomography (CT) in females. We reviewed the records of 1,687 female subjects who had undergone CT. They were divided into the following 2 age groups:group A (＜50 years) and group B (≥50 years). PE was diagnosed by the presence of low-attenuation areas using visual assessment (grades 0-3) on CT images. Two subtypes of PE were observed:centrilobular emphysema (CLE) and paraseptal emphysema (PSE). PE was divided into the following 3 categories:I (CLE or CLE-predominant);II (CLE and PSE of equal extent);and III (PSE or PSE-predominant). PE was found in 64 of 274 smokers (23.3%) and 54 of 1,413 non-smokers (3.8%). In smoking subjects, when grades 1 and 2 were grouped together as mild PE, the mean age for CT grade 3 (severe PE) was significantly higher than that for mild PE. In group A, category III predominated, whereas category I was more prevalent in group B, in both smoking and non-smoking subjects. A high incidence of PE was found in smoking subjects as compared with non-smoking subjects. PSE predominated in younger subjects, whereas CLE predominated in older subjects.

Diagnostic value of kinetic analysis using dynamic 18F-FDG-PET in patients with malignant primary brain tumor.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of quantitative imaging of glucose metabolism with positron emission tomography (PET) using kinetic analysis for differentiating between high-grade glioma and central nervous system (CNS) lymphoma. METHODS: Dynamic fluorine-18-fluorodeoxyglucose (18F-FDG)-PET scans obtained in 20 patients with high-grade glioma (World Health Organization grade III, five lesions; grade IV, 15 lesions) and in 12 patients with CNS lymphoma (16 lesions) were retrospectively reviewed. Applying a three-compartment model, parametric images of K1, k2, k3, and k4 and cerebral metabolic rate of glucose (CMR(Glc)) were obtained. RESULTS: On visual analysis, one grade III glioma lesion showed an increase of K1, k2, and k3 values as observed on their respective images. Four grade IV glioma lesions showed an increase of K1 and k2, 11 of k3, and six of CMR(Glc) on their respective images. Fourteen CNS lymphoma lesions showed an increase of K1, 16 of k3, two of k4, and 14 of CMR(Glc). Both k3 and CMR(Glc) values (mean+/-SD) of CNS lymphoma (0.096+/-0.046 and 77.4+/-37.7, respectively) were significantly higher than those of the normal gray matter (0.059+/-0.015 and 41.3+/-9.3, respectively; P<0.007 and P<0.002, respectively). The k3 value of CNS lymphoma was significantly higher than that of grade III (0.058+/-0.022) and grade IV (0.065+/-0.024) gliomas (P<0.03 and P<0.04, respectively). The CMR(Glc) value of CNS lymphoma was significantly higher than that of grade III (33.8+/-7.8) and grade IV (41.5+/-23.1) gliomas (P<0.001 and P<0.004, respectively). The value of k2 of CNS lymphoma was significantly lower than that of grade IV glioma (P<0.05). CONCLUSION: The direct measurement of the regional rate constants by kinetic analysis might be useful for the delineation of CNS lymphoma and for differential diagnosis of high-grade glioma and CNS lymphoma.

Dual time point FDG PET for evaluation of malignant pleural mesothelioma.

OBJECTIVE: To evaluate whether 2-deoxy-2-18F-fluoro-D-glucose (FDG) positron emission tomography (PET) is more useful in differentiating malignant from benign pleural lesions, and whether delayed FDG PET imaging can improve the diagnostic performance in patients with suspicion of malignant pleural mesothelioma (MPM). METHODS: Thirty-three patients who were suspected of having MPM were examined with FDG PET. PET imaging (whole body) was performed at 60 min (early) post-FDG injection and repeated at 120 min (delayed) after injection only in the thoracic region. We evaluated the FDG uptake visually and semiquantitatively. The semiquantitative analysis using the standardized uptake value (SUV) was determined for both early and delayed images (SUVearly and SUVdelayed, respectively). RESULTS: The final diagnosis was MPM in 17 patients and benign pleural disease in 16 patients. The sensitivity, specificity, and accuracy to detect MPM on both early and delayed PET were all 88%. The mean value of SUVdelayed in MPM was significantly higher than that of SUVearly (P < 0.001). The mean values of SUVearly and SUVdelayed in MPM were significantly higher than the corresponding values in benign pleural disease (P < 0.01, respectively). CONCLUSION: FDG PET seems to be a useful imaging modality for differential diagnosis of MPM. In addition, the diagnostic performance on delayed PET was the same as that on early PET, although SUVdelayed was significantly higher than SUVearly in patients with MPM.

Dual-time-point FDG-PET for evaluation of lymph node metastasis in patients with non-small-cell lung cancer.

OBJECTIVE: The objective of this study was to retrospectively evaluate whether delayed additional F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging can improve the certainty of this modality in evaluating lymph node metastasis in patients with non-small-cell lung cancer (NSCLC). METHODS: Eighty-three patients with NSCLC were examined. FDG-PET imaging (whole body) was performed at 1-h (early) post-FDG injection and repeated 2 h (delayed) after injection only in the thoracic area. The PET images were evaluated qualitatively for regions of focally increased metabolism. If a lymph node was visible on the PET image, the semi-quantitative analysis using the standardized uptake value (SUV) was determined for both early and delayed images (SUV(early) and SUV(delayed), respectively). Retention index (RI) was then calculated on the basis of the following equation: (SUV(delayed) - SUV(early)) x 100/SUV(early). The RI value of more than 0% was taken to be the PET criterion for malignancy. RESULTS: For early and delayed PET, sensitivities for lymph node staging were 54% and 62%, respectively, specificities were 89% for both, and accuracies were 78% and 81%, respectively. The results of combined delayed PET and RI showed a sensitivity of 62%, specificity of 96%, and accuracy of 86%. CONCLUSIONS: Dual-time-point FDG-PET (combined delayed PET and RI) showed better (although not statistically significant) specificity, positive predictive value, and accuracy than early or delayed PET alone for lymph node staging in NSCLC.

Comparison of (18)F-FLT PET and (18)F-FDG PET for preoperative staging in non-small cell lung cancer.

PURPOSE: The nucleoside analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) has been introduced for imaging cell proliferation with positron emission tomography (PET). We prospectively compared the diagnostic efficacy of FLT PET with that of 2-deoxy-2-(18)F-fluoro-D-glucose (FDG) PET for the preoperative nodal and distant metastatic staging of non-small cell lung cancer (NSCLC). METHODS: A total of 34 patients with NSCLC underwent FLT PET and FDG PET. PET imaging was performed at 60 min after each radiotracer injection. The PET images were evaluated qualitatively for regions of focally increased metabolism. For visualized primary tumors, the maximum standardized uptake value (SUV) was calculated. Nodal stages were determined by using the American Joint Committee on Cancer staging system and surgical and histologic findings reference standards. RESULTS: For the depiction of primary tumor, sensitivity of FLT PET was 67%, compared with 94% for FDG PET (P = 0.005). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for lymph node staging on a per-patient basis were 57, 93, 67, 89, and 85%, respectively, with FLT PET and 57, 78, 36, 91, and 74%, respectively, with FDG PET (P > 0.1 for all comparisons). Two of the three distant metastases were detected with FLT and FDG PET. CONCLUSION: In NSCLC, FLT PET showed better (although not statistically significant) specificity, positive predictive value and accuracy for N staging on a per-patient basis than FDG PET. However, FDG PET was found to have higher sensitivity for depiction of primary tumor than FLT PET.

Comparison of early and delayed FDG PET for evaluation of biliary stricture.

OBJECTIVE: We assessed whether delayed FDG PET imaging is more useful for the evaluation of biliary stricture in differential diagnosis of malignancy from benign disease. METHODS: Thirty-seven patients who underwent FDG PET for differential diagnosis of the disease causing biliary stricture were included. FDG PET imaging was performed at 70+/-12 min (early) post FDG injection and repeated 188+/-27 min (delayed) after injection only in the abdominal region. Image analysis was performed with visual interpretation and using a semi-quantitative method if lesion was visible on the PET image. The semi-quantitative analysis using the standardized uptake value (SUV) was determined for both early and delayed images (SUVearly and SUVdelayed, respectively). The tumour-to-normal liver (T/L) ratio was also calculated. RESULTS: The final diagnosis was cholangiocarcinoma in 29 and benign disease in eight patients. In cases of cholangiocarcinoma, visual analysis of FDG PET using the delayed images, improve the diagnosis with one more patient correctly identified. For early and delayed FDG PET, sensitivities were 82.8% and 86.2%, respectively; specificities were 87.5% for both; and accuracies were 83.8% and 86.5%, respectively. Both SUV and T/L ratio derived from delayed images were significantly higher than those derived from early images for cholangiocarcinoma (P<0.0002 and P<0.0001, respectively). CONCLUSION: FDG PET could be useful for differential diagnosis of malignancy from benign disease in patients with biliary stricture. Especially, the delayed targeted FDG PET imaging can be recommended in those patients when early imaging is negative or equivalent, because of increased lesion uptake and increased lesion to background contrast ratio.

Dual-time-point 18F-FDG PET for the evaluation of gallbladder carcinoma.

UNLABELLED: Conventional imaging techniques such as ultrasonography, CT, and MRI are able to detect gallbladder abnormalities but are not always able to differentiate a malignancy from other disease processes such as cholecystitis. The purpose of the present study was to evaluate the efficacy of dual-time-point (18)F-FDG PET for differentiating malignant from benign gallbladder disease. METHODS: The study evaluated 32 patients who were suspected of having gallbladder tumors. (18)F-FDG PET (whole body) was performed at 62 +/- 8 min (early) after (18)F-FDG injection and was repeated 146 +/- 14 min (delayed) after injection only in the abdominal region. We evaluated the (18)F-FDG uptake both visually and semiquantitatively. Semiquantitative analysis using the standardized uptake value (SUV) was performed for both early and delayed images (SUV(early) and SUV(delayed), respectively). The retention index (RI) was calculated according to the equation (SUV(delayed) - SUV(early)) x 100/SUV(early). The tumor-to-liver ratio was also calculated. RESULTS: The final diagnosis was gallbladder carcinoma in 23 patients and benign disease in 9 patients. For visual analysis of gallbladder carcinoma, delayed (18)F-FDG PET images improved the specificity of diagnosis in 2 patients. When an SUV(early) of 4.5, SUV(delayed) of 2.9, and RI of -8 were chosen as arbitrary cutoffs for differentiating between malignant and benign conditions, sensitivity increased from 82.6% to 95.7% and 100% for delayed imaging and combined early and delayed imaging (i.e., RI), respectively. With the same criteria, specificity decreased from 55.6% to 44.4% for delayed imaging and combined early and delayed imaging, respectively. The specificity of (18)F-FDG PET improved to 80% in the group with a normal level of C-reactive protein (CRP) and decreased to 0% in the group with an elevated CRP level. For gallbladder carcinoma, both SUV and tumor-to-liver ratios derived from delayed images were significantly higher than the ratios derived from early images (P < 0.0001). CONCLUSION: Delayed (18)F-FDG PET is more helpful than early (18)F-FDG PET for evaluating malignant lesions because of increased lesion uptake and increased lesion-to-background contrast. However, the diagnostic performance of (18)F-FDG PET depends on CRP levels.