The present state of radiation exposure from pediatric CT examinations in Japan-what do we have to do?

The use of computed tomography (CT) has increased dramatically over the past several decades and has resulted in a concurrent increase in medical exposure to ionizing radiation. Several recent studies have examined the link between medical radiation and the risk of cancer, especially in children. The cancer risk associated medical exposure has not been definitively confirmed. However, we have to reduce unwarranted medical radiation exposure in pediatric patients. Justification and optimization are of great importance in order to minimize these risks, and the standardization of CT usage is essential. However, in Japan no clinical guidelines for the use of CT have been commonly agreed upon, especially in children. Furthermore, the CT-associated radiation exposure in Japan varies widely among the different facilities. Further studies based on a nationwide survey in Japan will be required in order to establish simple and useful clinical guidelines.

Comparison of long-labeled pseudo-continuous arterial spin labeling (ASL) features between young and elderly adults: special reference to parameter selection.

BACKGROUND: The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations. PURPOSE: To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL. MATERIAL AND METHODS: The perfusion signal was simulated in four LDs and theoretical signal-to-noise ratio efficiency (SNReff) was calculated. In vivo studies were performed on a 3.0 T magnetic resonance imaging (MRI) scanner and 15 volunteers were categorized into either the young or elderly adult groups. We compared the differences in CBF values with or without ATT correction. RESULTS: Regarding signal simulation, perfusion signal increased with the length of LD. SNReff also improved with LD, but SNReff plateaued at an LD of 3.0 s. As for the in vivo study, SNR linearly increased along with the LD. The CBF differences with the correction of ATT were larger in the elderly adult group. This trend was most prominent in the longer ATT area in the occipital cortical region. CONCLUSION: A combination of imaging settings of LD = 3.5 s and PLD = 2.0 s were suggested as optimal imaging parameters for allowing acceptable CBF quantification and sufficient SNR in both young and elderly individuals.

Arterial Transit Time-corrected Renal Blood Flow Measurement with Pulsed Continuous Arterial Spin Labeling MR Imaging.

PURPOSE: The importance of arterial transit time (ATT) correction for arterial spin labeling MRI has been well debated in neuroimaging, but it has not been well evaluated in renal imaging. The purpose of this study was to evaluate the feasibility of pulsed continuous arterial spin labeling (pcASL) MRI with multiple post-labeling delay (PLD) acquisition for measuring ATT-corrected renal blood flow (ATC-RBF). MATERIALS AND METHODS: A total of 14 volunteers were categorized into younger (n = 8; mean age, 27.0 years) and older groups (n = 6; 64.8 years). Images of pcASL were obtained at three different PLDs (0.5, 1.0, and 1.5 s), and ATC-RBF and ATT were calculated using a single-compartment model. To validate ATC-RBF, a comparative study of effective renal plasma flow (ERPF) measured by 99mTc-MAG3 scintigraphy was performed. ATC-RBF was corrected by kidney volume (ATC-cRBF) for comparison with ERPF. RESULTS: The younger group showed significantly higher ATC-RBF (157.68 ± 38.37 mL/min/100 g) and shorter ATT (961.33 ± 260.87 ms) than the older group (117.42 ± 24.03 mL/min/100 g and 1227.94 ± 226.51 ms, respectively; P < 0.05). A significant correlation was evident between ATC-cRBF and ERPF (P < 0.05, r = 0.47). With suboptimal single PLD (1.5 s) settings, there was no significant correlation between ERPF and kidney volume-corrected RBF calculated from single PLD data. CONCLUSION: Calculation of ATT and ATC-RBF by pcASL with multiple PLD was feasible in healthy volunteers, and differences in ATT and ATC-RBF were seen between the younger and older groups. Although ATT correction by multiple PLD acquisitions may not always be necessary for RBF quantification in the healthy subjects, the effect of ATT should be taken into account in renal ASL-MRI as debated in brain imaging.

Assessment of the Tumor Redox Status in Head and Neck Cancer by 62Cu-ATSM PET.

PURPOSE: Tumor redox is an important factor for cancer progression, resistance to treatments, and a poor prognosis. The aim of the present study was to define tumor redox (over-reduction) using 62Cu-diacetyl-bis(N4-methylthiosemicarbazone) (62Cu-ATSM) PET and compare its prognostic potential in head and neck cancer (HNC) with that of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG). METHODS: Thirty HNC patients (stage II-IV) underwent pretreatment 62Cu-ATSM and 18F-FDG PET scans. Maximum standardized uptake values (SUVATSM and SUVFDG) and tumor-to-muscle activity concentration ratios (TMRATSM and TMRFDG) were measured. Reductive-tumor-volume (RTV) was then determined at four thresholds (40%, 50%, 60%, and 70% SUVATSM), and total-lesion-reduction (TLR) was calculated as the product of the mean SUV and RTV for 62Cu-ATSM. In 18F-FDG, metabolic-tumor-volume (MTV) and total-lesion-glycolysis (TLG) were obtained at a threshold of 40%. A ROC analysis was performed to determine % thresholds for RTV and TLR showing the best predictive performance, and these were then used to determine the optimal cut-off values to stratify patients for each parameter. Progression-free-survival (PFS) and cause-specific-survival (CSS) were evaluated by the Kaplan-Meier method. RESULTS: The means ± standard deviations of PFS and CSS periods were 16.4±13.4 and 19.2±12.4 months, respectively. A ROC analysis determined that the 70% SUVATSM threshold for RTV and TLR was the best for predicting disease progression and cancer death. Optimal cut-offs for each index were SUVATSM = 3.6, SUVFDG = 7.9, TMRATSM = 3.2, TMRFDG = 5.6, RTV = 2.9, MTV = 8.1, TLR = 14.0, and TLG = 36.5. When the cut-offs for TMRATSM and TLR were set as described above in 62Cu-ATSM PET, patients with higher TMRATSM (p = 0.03) and greater TLR (p = 0.02) showed significantly worse PFS, while patients with greater TLR had significantly worse CSS (p = 0.02). Only MTV in 18F-FDG PET predicted differences in PSF and CSS (p = 0.03 and p = 0.03, respectively). CONCLUSION: Tumor redox parameters measured by 62Cu-ATSM PET may be determinants of HNC patient outcomes and help define optimal patient-specific treatments.

Different Prognostic Implications of 18F-FDG PET Between Histological Subtypes in Patients With Cervical Cancer.

This study aimed to investigate whether the predictive values of intensity- and volume-based PET parameters are different between histological subtypes in patients with cervical cancer. Ninety patients, 65 with squamous cell carcinoma (SCC) and 25 with non-SCC (NSCC), who underwent pretreatment ¹8F-FDG PET/CT and pelvic MRI, were studied retrospectively. In addition to SUVmax and SUVmean, metabolic-tumor-volume (MTV) was determined by thresholding of 40% SUVmax and total-lesion-glycolysis (TLG) was calculated. Clinical factors and PET metabolic indices were compared between SCC and NSCC. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method with cut-offs determined by ROC analyses to stratify SCC and NSCC patients separately. Factors associated with survival were assessed with univariate and multivariate analyses using the Cox regression model. No significant differences were observed in clinical factors other than tumor size or ¹8F-FDG PET metabolic indices between SCC and NSCC. The Kaplan-Meier estimates of 2-year PFS and OS rates were 60% and 70% for SCC and 40% and 76% for NSCC, respectively. Multivariate analyses showed that MTV and TLG were the independent prognostic factors for PFS and OS in SCC; in contrast, SUVmax was the independent prognostic factor for PFS and OS in NSCC. Metabolic burden (MTV and TLG) could be beneficial for the prognostic prediction of cervical SCC patients; in contrast, metabolic intensity (SUVmax) could be beneficial for the prognostic prediction of NSCC patients. The different prognostic implications might be based on the differences of tissue integrity and histological heterogeneity between SCC and NSCC.

Prognostic Value of Dual-Time-Point 18F-FDG PET for Idiopathic Pulmonary Fibrosis.

UNLABELLED: The aim of this prospective study was to clarify whether dual-time-point (18)F-FDG PET imaging results are useful to predict long-term survival of idiopathic pulmonary fibrosis (IPF) patients. METHODS: Fifty IPF patients underwent (18)F-FDG PET examinations at 2 time points: 60 min (early imaging) and 180 min (delayed imaging) after (18)F-FDG injection. The standardized uptake value (SUV) at each point and retention index value (RI-SUV) calculated from those were evaluated, and then the results were compared with overall and progression-free survival. RESULTS: A multivariate Cox proportional hazards model showed higher RI-SUV and higher extent of fibrosis score as independent predictors of shorter progression-free survival. The median progression-free survival for patients with negative RI-SUV was better than that for those with positive RI-SUV (27.9 vs. 13.3 mo, P = 0.0002). On the other hand, multivariate Cox analysis showed higher RI-SUV and lower forced vital capacity to be independent predictors of shorter overall survival. The 5-y survival rate for patients with negative RI-SUV was better than that for those with positive RI-SUV (76.8% vs. 14.3%, P = 0.00001). In addition, a univariate Cox model showed that positive RI-SUV as a binary variable was a significant indicator of mortality (hazard ratio, 7.31; 95% confidence interval, 2.64-20.3; P = 0.0001). CONCLUSION: Our results demonstrate that positive RI-SUV is strongly predictive of earlier deterioration of pulmonary function and higher mortality in patients with IPF.

Serial changes of (18)F-FDG PET/CT findings in ischiopubic synchondrosis: comparison with contrast-enhanced MRI.

UNLABELLED: A 3 years old female patient underwent resection and chemotherapy for a yolk sac tumor of the retroperitoneum. Two years later, fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) showed high uptake in the right ischiopubic synchondrosis (IPS), which had a radiolucent structure on CT. The structure showed contrast enhancement on magnetic resonance imaging (MRI), which was a non-specific finding. Six weeks later, a follow-up (18)F-FDG PET/CT scan was performed which showed no abnormal uptake in the IPS. The disappearance of (18)F-FDG uptake preceded that of contrast enhancement on MRI, which was seen 7 months after the initial (18)F-FDG PET/CT scan. CONCLUSION: This is the first report showing serial changes of (18)F-FDG uptake in IPS, in comparison to MRI findings.

Evaluation of staging and early response to chemotherapy with whole-body diffusion-weighted MRI in malignant lymphoma patients: A comparison with FDG-PET/CT.

BACKGROUND: To examine the utility of diffusion-weighted MRI (DW-MRI) for staging and early response to chemotherapy assessment in lymphoma patients as compared with fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). METHODS: Twenty-eight patients with histologically confirmed malignant lymphoma underwent both MRI and FDG-PET/CT before (pretreatment) and after two courses of chemotherapy (mid-treatment). Staging with MRI (DW-MRI alone and with T2-weighted images) and FDG-PET was compared visually, and the concordance rate (kappa value, κ) was calculated. To evaluate early response to chemotherapy, patients were divided into two groups, lesion-positive (LP) and lesion-negative (LN), based on a proposed original criterion. Progression-free survival (PFS) was compared between the groups using the Kaplan-Meier method. RESULTS: The stage diagnosed with DW-MRI alone and with FDG-PET/CT was concordant in 22 patients (κ = 0.71; P < 0.05), and by adding T2-weighted images, the number of concordant patients increased to 26 (κ = 0.90; P < 0.05). On mid-treatment imaging, 19 patients were diagnosed as LN from both modalities. PFS differed significantly between LP and LN on both DW-MRI (P = 0.0013) and FDG-PET/CT (P = 0.037). CONCLUSION: DW-MRI is a promising tool for staging and evaluation of early response to chemotherapy in patients with lymphoma.

Standardized uptake value differences between primary and metastatic lesions in ¹8F-FDG PET/CT of patients with lung cancer.

BACKGROUND: FDG-PET/CT is a robust tool for staging of lung cancer, but the differences in FDG uptake between primary and metastatic lesions have not yet been well described. PURPOSE: To define the potential range of standardized uptake value (SUV) differences between primary and metastatic lesions in lung cancer patients and to identify the factors responsible for these differences. MATERIAL AND METHODS: FDG-PET/CT images of 75 lung cancers with 296 metastases were analyzed retrospectively. Histological types, primary locations, and metastatic sites were recorded. The average and maximum SUV (SUVavg, SUVmax) of each primary tumor and metastasis were measured, and the ratio of metastatic SUVs to primary SUVs (M/Pavg, M/Pmax), its difference from 100% (diff-M/Pavg, diff-M/Pmax), the ratio of ROI area of metastatic to primary lesions (ROI-M/P), and its difference from 100% (diff-ROI-M/P) were calculated. RESULTS: M/Pavg was in the range of 35.9-224.6% (mean ± SD: 97.9% ± 35.9%), while M/Pmax was in the range of 24.8-286.7% (98.1% ± 45.3%). Furthermore, values were in the range of 50-200% for M/Pavg in 280/296 lesions (94.6%) and for M/Pmax in 255/296 lesions (86.1%). M/Pavg and M/Pmax showed significant linear correlations with ROI-M/P (r = 0.62, 0.64, respectively). Multivariate analysis showed that diff-ROI-M/P had the greatest effect on diff-M/Pavg and diff-M/Pmax. CONCLUSION: The SUVs of most metastatic lesions ranged from half to double those of primaries in lung cancer patients. When the SUV of a suspected metastasis is beyond the range of half to double that of the primary lung cancer, other non-metastatic lesions should be considered, while taking ROI size into account.

(18)F-FDG uptake predicts diagnostic yield of transbronchial biopsy in peripheral lung cancer.

OBJECTIVES: Recent advances in endobronchial ultrasonography with a guide sheath (EBUS-GS) have enabled better visualization of distal airways, while virtual bronchoscopic navigation (VBN) has been shown useful as a guide to navigate the bronchoscope. However, indications for utilizing VBN and EBUS-GS are not always clear. To clarify indications for a bronchoscopic examination using VBN and EBUS-GS, we evaluated factors that predict the diagnostic yield of a transbronchial biopsy (TBB) procedure for peripheral lung cancer (PLC) lesions. METHODS: We retrospectively reviewed the charts of 194 patients with 201 PLC lesions (≤3cm mean diameter), and analyzed the association of diagnostic yield of TBB with [(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) positron emission tomography and chest computed tomography (CT) findings. RESULTS: The diagnostic yield of TBB using VBN and EBUS-GS was 66.7%. High maximum standardized uptake value (SUVmax), positive bronchus sign, and ground-glass opacity component shown on CT were all significant predictors of diagnostic yield, while multivariate analysis showed only high (18)F-FDG uptake (SUVmax ≥2.8) and positive bronchus sign as significant predictors. Diagnostic yield was higher for PLC lesions with high (18)F-FDG uptake (SUVmax ≥2.8) and positive bronchus sign (84.6%) than for those with SUVmax <2.8 and negative bronchus sign (33.3%). High (18)F-FDG uptake was also correlated with tumor invasiveness. CONCLUSIONS: High (18)F-FDG uptake predicted the diagnostic yield of TBB using VBN and EBUS-GS for PLC lesions. (18)F-FDG uptake and bronchus sign may indicate for the accurate application of bronchoscopy with those modalities for diagnosing PLC.

(18)F-FDG PET/CT for Diagnosis of Osteosclerotic and Osteolytic Vertebral Metastatic Lesions: Comparison with Bone Scintigraphy.

STUDY DESIGN: A retrospective study. PURPOSE: The aims of this study were to investigate the diagnostic value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in PET/computed tomography (CT) in the evaluation of spinal metastatic lesions. OVERVIEW OF LITERATURE: Recent studies described limitations regarding how many lesions with abnormal (18)F-FDG PET findings in the bone show corresponding morphologic abnormalities. METHODS: The subjects for this retrospective study were 227 patients with primary malignant tumors, who were suspected of having spinal metastases. They underwent combined whole-body (18)F-FDG PET/CT scanning for evaluation of known neoplasms in the whole spine. (99m)Tc-methylene diphosphonate bone scan was performed within 2 weeks following PET/CT examinations. The final diagnosis of spinal metastasis was established by histopathological examination regarding bone biopsy or magnetic resonance imaging (MRI) findings, and follow-up MRI, CT and (18)F-FDG PET for extensively wide lesions with subsequent progression. RESULTS: From a total of 504 spinal lesions in 227 patients, 224 lesions showed discordant image findings. For 122 metastatic lesions with confirmed diagnosis, the sensitivity/specificity of bone scan and FDG PET were 84%/21% and 89%/76%, respectively. In 102 true-positive metastatic lesions, the bone scan depicted predominantly osteosclerotic changes in 36% and osteolytic changes in 19%. In 109 true-positive lesions of FDG PET, osteolytic changes were depicted predominantly in 38% while osteosclerotic changes were portrayed in 15%. CONCLUSIONS: (18)F-FDG PET in PET/CT could be used as a substitute for bone scan in the evaluation of spinal metastasis, especially for patients with spinal osteolytic lesions on CT.

Imaging the early response to chemotherapy in advanced lung cancer with diffusion-weighted magnetic resonance imaging compared to fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography.

PURPOSE: To evaluate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) for assessment of the early response to chemotherapy and outcome in patients with advanced lung cancer through comparison with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT). MATERIALS AND METHODS: Twenty-eight lung cancer patients underwent DW-MRI, FDG-PET, and CT before and after one course of chemotherapy. Changes in the apparent diffusion coefficient (ΔADC), the mean standardized uptake value (ΔSUV), and the maximum diameter (ΔMD) were measured and compared. According to the response evaluation criteria, patients were divided into two groups, responders and nonresponders, and progression-free survival (PFS) and overall survival (OS) were estimated. RESULTS: The relationship between ΔADC and ΔSUV had the highest correlation coefficient. A cutoff value of ΔADC between responders and nonresponders was estimated as 21.5%. PFS and OS between responders and nonresponders were significantly different on DW-MRI (PFS, P = 0.012; OS, P = 0.006) and on FDG-PET (PFS, P = 0.017; OS, P = 0.036), but not on CT (PFS, P = 0.105; OS, P = 0.051). CONCLUSION: DW-MRI can be used to predict prognosis in patients with advanced lung cancer.

Fluorodeoxyglucose accumulation in the left atrial appendage of a patient with paroxysmal atrial fibrillation.

A 69-year-old man with a history of paroxysmal atrial fibrillation (PAF) and subsequent cerebral infarction was referred to our hospital because of an abnormal accumulation of 18F-fluorodeoxyglucose (FDG) in the left atrial appendage (LAA) that was detected on positron emission tomography-computed tomography (PET-CT) imaging during a health screening. Transesophageal echocardiography (TEE) demonstrated thrombus formation in the LAA. Even after the thrombus disappeared by strictly guided oral anticoagulant therapy, intense abnormal FDG uptake in the LAA on PET-CT imaging persisted. In low-risk patients such as this, inflammation may have played some role in LAA thrombus formation.

Differentiation of histological subtypes in lung cancer with 18F-FDG-PET 3-point imaging and kinetic analysis.

The purpose of this study was to evaluate differences in histological subtypes of lung cancer using (18)F-FDG-PET 3-point imaging and kinetic analysis. Subjects comprised 44 patients with histologically proven lung cancer (squamous cell carcinoma (SCC), n=18; well-differentiated adenocarcinoma (WDA), n=9; poorly/moderately differentiated adenocarcinoma (non-WDA), n=17) who underwent (18)F-FDG-PET/CT examinations at 1, 2 h and 3 h after injection of 185 MBq of (18)F-FDG, approximately. Mean standardized uptake value (SUV) in each lesion was measured at each time point and the increase rate of SUV (IR_SUV) was calculated. SUV and IR_SUV were compared among the 3 groups. In addition, to estimate differences in kinetic parameters for each group, kinetic analysis based on a 3-compartment model was performed. Our results showed SUV differed significantly at every time point among the 3 groups. IR_SUV between 2 and 3 h post-injection (IR_SUV (2-3)) differed significantly among the 3 groups, while both IR_SUV(1-3) and IR_SUV(1-2) were significantly higher in SCC than in WDA. In kinetic analyses, both K1 and k3 showed significant differences among the 3 groups, with highest values in SCC and lowest in WDA. In conclusion, (18)F-FDG-PET 3-point imaging and kinetic analysis enabled the differentiation of histological subtypes in lung cancer, arising from differences in glucose transporter density and enzymatic activity of hexokinase.

Role of PET/CT in gynecological tumors based on the revised FIGO staging classification.

FDG PET/CT imaging offers important information for the pre-, intra-, and postoperative management of gynecologic tumors. A review of FDG PET/CT imaging for the diagnosis of gynecologic tumors based on the revised International Federation of Gynecology and Obstetrics staging classification is presented.

Kikuchi-Fujimoto disease: PET/CT assessment of a rare cause of cervical lymphadenopathy.

PURPOSE: Kikuchi-Fujimoto disease (KFD), formerly called subacute necrotizing lymphadenitis, is a rare cause of cervical lymphadenopathy. The purpose of this study was to evaluate the usefulness of FDG PET/CT for distinguishing KFD from non-Hodgkin lymphoma (NHL). MATERIALS AND METHODS: Twenty-two patients with cervical lymphadenopathy (8 with KFD and 14 with NHL) underwent CT and FDG PET/CT scans to examine the cervical lymphadenopathy. Regional values of FDG uptake were evaluated using the standardized uptake value (SUV) and partial volume corrected SUV (corSUV) based on the count recovery coefficient. Tumor size (mm), SUV, and corSUV were compared among KFD, indolent NHL, and aggressive NHL. RESULTS: KFD lesions tended to be smaller (13.8 ± 5.4 mm) than those of indolent (25.4 ± 11.8) and aggressive (29.7 ± 18.8) NHL, whereas there were no significant differences in size. As for SUV, a significant difference was observed only between indolent and aggressive (6.4 ± 1.5 and 17.3 ± 9.3, P < 0.05) NHL; however, KFD showed a significantly greater corSUV (23.8 ± 10.6) as compared with indolent NHL (9.2 ± 5.1, P < 0.05), which did not show a significant difference from aggressive NHL (21.4 ± 10.2). FDG PET/CT detected thoracoabdominal lesions in 2 patients (25%) with KFD. CONCLUSIONS: KFD shows high FDG uptake for size, which may reflect the pathologic characteristics, including necrotizing lymphocytes and numerous histiocytes (macrophages) surrounding small necrotic foci. FDG PET/CT will be useful for detecting noncervical lesions of KFD and distinguishing KFD from NHLs using both SUV and corSUV.

Prognostic value of dual-time-point 18F-fluorodeoxyglucose positron emission tomography in patients with pulmonary sarcoidosis.

BACKGROUND AND OBJECTIVE: The value of dual-time- point (18) F-FDG PET was investigated to predict the prognosis of patients with pulmonary sarcoidosis. METHODS: Twenty-one patients with pulmonary sarcoidosis underwent (18) F-FDG PET examinations at two time points: an early scan at 60min and a delayed scan at 180min after injection of (18) F-FDG. Standardized uptake values (SUVs) at the two time points and the retention index (RI-SUV) calculated from these were evaluated. To evaluate disease progression, all patients underwent chest CT 1year after (18) F-FDG PET. Using these results, the accuracy of (18) F-FDG PET parameters and (67) Ga uptake for predicting disease persistence were compared, and the correlations between those parameters and serum markers were assessed. RESULTS: RI-SUV was significantly higher in patients with increased or unchanged pulmonary lesions at follow-up CT (persistent group; 21.3±9.6%) than in patients with improved pulmonary lesions (improved group; -9.2±28.6%, P=0.0075). The diagnostic accuracy of RI-SUV in the persistent group was significantly greater than that of early SUV or (67) Ga uptake, and serum soluble IL-2 receptor showed a significant correlation with RI-SUV. CONCLUSIONS: RI-SUV showed better diagnostic accuracy compared with early SUV or (67) Ga uptake, in patients with persistent lung involvement at 1year. It may be a useful measure of persistent inflammation in patients with pulmonary sarcoidosis.

Embolic infarction followed by serial bone SPECT and MR fusion images--the door to SPECT/MR-.

We recently experienced a case of cerebral infarction incidentally found by whole body bone scintigraphy for the detection of bone metastasis from renal cell carcinoma. Additional bone SPECT and brain MR fusion images clearly demonstrated the wedge-shaped uptake of tracer corresponded to the abnormal intensity reflecting subacute cerebral infarction. Follow-up bone scan and fused images with MRI showed complete resolution of the abnormal uptake in chronic phase. A breakdown in the normal blood-brain barrier results in abnormal ionic calcium flux into the cells following altered cell membrane integrity leading to precipitation of calcium salts which eventually binds to bone imaging tracer such as (99m)Tc-methylene diphosphonate. That is, increased accumulation of bone seeking agents represents lethal cell death. The recent development of software and hardware has enabled the fusion of functional and anatomic images. Image fusion between SPECT with various tracers and MRI is expected to provide clues as to the underlying cause of diseases and to decide our treatment planning in the near future.

Effects of alendronate on bone metabolism in glucocorticoid-induced osteoporosis measured by 18F-fluoride PET: a prospective study.

UNLABELLED: Osteoporosis represents a significant side effect of glucocorticoid therapy, and alendronate has been reported to prevent this glucocorticoid-induced osteoporosis. Functional imaging with (18)F-fluoride PET allows quantitative analysis of bone metabolism in specific skeletal regions. However, only a few studies have quantitatively determined bone turnover and metabolism in glucocorticoid-induced osteoporosis by radiologic imaging techniques including PET. The aim of this study was to examine changes in regional bone remodeling and turnover as measured by (18)F-fluoride PET, the relationship between these measured changes and conventional bone metabolism parameters, and the effect of alendronate treatment. METHODS: The study group consisted of 24 postmenopausal women (mean age, 59.7 y) who had various diseases, excluding rheumatoid arthritis, and had been treated with 10 mg or more of oral glucocorticoids (prednisolone equivalent) per day for more than 6 mo. Treatment with 5 mg of alendronate per day began at the time of study entry and continued for 12 mo. (18)F-fluoride PET was performed at baseline, 3 mo, and 12 mo to determine localized bone turnover, and the results were compared with other bone metabolism parameters. RESULTS: Lumbar spine standardized uptake values (SUVs) were significantly lower (P < 0.05) in the osteoporotic group (T-score < or = -2.5) than in the group that was healthy or osteopenic (T-score > -2.5). Patients treated with alendronate for 12 mo exhibited significant decreases in serum bone-specific alkaline phosphate (P < 0.05), urinary N-telopeptide for type I collagen (P < 0.01), lumbar spine SUV (P < 0.01), and femoral neck SUV (P < 0.01) in association with a gradual increase in bone mineral density (BMD) of the lumbar spine relative to the baseline value (P < 0.05). Although there was a significant correlation between BMD and SUV in the lumbar spine at baseline (P < 0.05), there was no correlation between the 2 variables at 12 mo of treatment with alendronate. CONCLUSION: Alendronate treatment resulted in significant decreases in bone metabolism and turnover in the lumbar spine. It also led to an increase in BMD of the lumbar spine in patients with glucocorticoid-induced osteoporosis. Our findings suggest that antiresorptive therapy has a direct bone-metabolism effect on skeletal kinetics in glucocorticoid-induced osteoporosis at the clinically important site of the lumbar spine.