Right Ventricular to Pulmonary Artery Uncoupling Is Associated With Impaired Exercise Capacity in Patients With Transthyretin Cardiac Amyloidosis.

BACKGROUND: Exercise capacity is related to mortality and morbidity in heart failure (HF) patients. Determinants of exercise capacity in transthyretin cardiac amyloidosis (ATTR-CA) have not been established. METHODS AND RESULTS: This single-center study retrospectively evaluated ATTR-CA patients and patients with non-amyloidosis HF with preserved/mildly reduced ejection fraction (HFpEF/HFmrEF) (n=32 and n=51, respectively). In the ATTR-CA group, the median age was 75.5 years (interquartile range [IQR] 71.3-78.8 years), 90.6% were male, and the median left ventricular (LV) ejection fraction was 53.5% (IQR 41.4-65.6%). Cardiopulmonary exercise tests revealed a median peak oxygen consumption and anaerobic threshold of 15.9 (IQR 11.6-17.4) and 10.6 (IQR 8.5-12.0] mL/min/kg, respectively, and ventilatory efficiency (minute ventilation/carbon dioxide production [V̇E/V̇CO2] slope) of 35.5 (IQR 32.0-42.5). Among exercise variables, V̇E/V̇CO2slope has the greatest prognostic value. Univariate analysis revealed a significant correlation between V̇E/V̇CO2slope and age, LV global longitudinal strain, tricuspid annular plain systolic excursion/pulmonary arterial systolic pressure (TAPSE/PASP) ratio, and mixed venous oxygen saturation. In multivariate analyses, the TAPSE/PASP ratio was an independent predictor of V̇E/V̇CO2slope (95% confidence interval -44.5, -10.8; P=0.0067). In non-amyloidosis HFpEF/HFmrEF patients, the TAPSE/PASP ratio was not independently correlated with V̇E/V̇CO2slope. CONCLUSIONS: Right ventricular-pulmonary artery coupling estimated by the TAPSE/PASP ratio determines exercise capacity in ATTR-CA patients. This highlights the importance of early therapeutic intervention against underappreciated right ventricular dysfunction associated with ATTR-CA.

Different Impact of Immunosuppressive Therapy on Cardiac Outcomes in Systemic Versus Isolated Cardiac Sarcoidosis.

Isolated cardiac sarcoidosis (iCS) is increasingly recognized; however, its prognosis and the efficacy of immunosuppressive therapy remain undetermined. We aimed to compare the prognosis of iCS and systemic sarcoidosis including cardiac involvement (sCS) under immunosuppressive therapy.We retrospectively reviewed the clinical data of 42 patients with sCS and 30 patients with iCS diagnosed at Kyushu University Hospital from 2004 through 2022. We compared the characteristics and the rate of adverse cardiac events including cardiac death, fatal ventricular tachyarrhythmia, and heart failure hospitalization between the 2 groups. The median follow-up time was 1535 [interquartile range, 630-2555] days, without a significant difference between the groups. There were no significant differences in gender, NYHA class, or left ventricular ejection fraction. Immunosuppressive agents were administered in 86% of sCS and in 73% of iCS patients (P = 0.191). When analyzed only with patients receiving immunosuppressive therapy (sCS, n = 36; iCS, n = 21), the cardiac event-free survival was significantly lower in iCS than sCS (37% versus 79%, P = 0.002). Myocardial LGE content at the initial diagnosis was comparable in both groups. The disease activity was serially evaluated in 26 sCS and 16 iCS patients by quantitative measures of FDG-PET including cardiac metabolic volume and total lesion glycolysis, representing 3-dimensional distribution and intensity of inflammation in the entire heart. Although iCS patients had lower baseline disease activity than sCS patients, immunosuppressive therapy did not attenuate disease activity in iCS in contrast to sCS.iCS showed a poorer response to immunosuppressive therapy and a worse cardiac prognosis compared to sCS despite lower baseline disease activity.

Efficacy of Dynamic Chest Radiography for Chronic Thromboembolic Pulmonary Hypertension.

Background While current guidelines require lung ventilation-perfusion (V/Q) scanning as the first step to diagnose chronic pulmonary embolism in pulmonary hypertension (PH), its use may be limited by low availability and/or exposure to ionizing radiation. Purpose To compare the performance of dynamic chest radiography (DCR) and lung V/Q scanning for detection of chronic thromboembolic PH (CTEPH). Materials and Methods Patients with PH who underwent DCR and V/Q scanning in the supine position from December 2019 to July 2021 were retrospectively screened. The diagnosis of CTEPH was confirmed with right heart catheterization and invasive pulmonary angiography. Observer tests were conducted to evaluate the diagnostic accuracy of DCR and V/Q scanning. The lungs were divided into six areas (upper, middle, and lower for both) in the anteroposterior image, and the number of lung areas with thromboembolic perfusion defects was scored. Diagnostic performance was compared between DCR and V/Q scanning using the area under the receiver operating characteristic curve. Agreement between the interpretation of DCR and that of V/Q scanning was assessed using the Cohen kappa coefficient and percent agreement. Results A total of 50 patients with PH were analyzed: 29 with CTEPH (mean age, 64 years ± 15 [SD]; 19 women) and 21 without CTEPH (mean age, 61 years ± 22; 14 women). The sensitivity, specificity, and accuracy of DCR were 97%, 86%, and 92%, respectively, and those of V/Q scanning were 100%, 86%, and 94%, respectively. Areas under the receiver operating characteristic curve for DCR and V/Q scanning were 0.92 (95% CI: 0.79, 0.97) and 0.93 (95% CI: 0.78, 0.98). Agreement between the consensus interpretation of DCR and that of V/Q scanning was substantial (κ = 0.79 [95% CI: 0.61, 0.96], percent agreement = 0.9 [95% CI: 0.79, 0.95]). Conclusion Dynamic chest radiography had similar efficacy to ventilation-perfusion scanning in the detection of chronic thromboembolic pulmonary hypertension. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Wandtke and Koproth-Joslin in this issue.

Prognostic outcome and complications of sentinel lymph node navigation surgery for early-stage cervical cancer.

BACKGROUND: To evaluate the prognostic outcome and surgical complications in patients with early-stage cervical cancer who underwent sentinel node navigation surgery (SNNS) for hysterectomy or trachelectomy. METHODS: A total of 139 patients who underwent SNNS using 99mTc phytate between 2009 and 2015 were evaluated. No further lymph node dissection was performed when intraoperative analysis of the sentinel lymph nodes (SLNs) was negative for metastasis. We compared the surgical complications between the SNNS group and 67 matched patients who underwent pelvic lymph node dissection (PLND) after SLN mapping between 2003 and 2008. We also examined the clinical outcomes in the SNNS group. RESULTS: The mean number of detected SLNs was 2.5 per patient. Fourteen of the 139 patients in the SNNS group underwent PLND based on the intraoperative SLN results. The amount of blood loss, the operative time, and the number of perioperative complications were significantly less in the SNNS group than in the matched PLND group. There was no recurrence during a follow-up period ranging from 2 to 88 months (median 40 months) in the SNNS group. CONCLUSIONS: Using SNNS for early-stage cervical cancer is safe and effective and does not increase the recurrence rate. A future multicenter trial is warranted.

Diagnostic utility of intravoxel incoherent motion mr imaging in differentiating primary central nervous system lymphoma from glioblastoma multiforme.

PURPOSE: To evaluate the diagnostic performance of intravoxel incoherent motion (IVIM) MR imaging and 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating primary central nervous system lymphoma (PCNSL) from glioblastoma multiforme (GBM). MATERIALS AND METHODS: Fifty patients, 17 with PCNSL and 33 with GBM, were retrospectively studied. From the 3 Tesla IVIM data, the perfusion fraction (f) and diffusion coefficient (D) were obtained. In addition, the maximum standard uptake value (SUVmax ) was obtained from the FDG-PET data. Each of the three parameters was compared between PCNSL and GBM using Mann-Whitney U-test. The performance in discriminating between PCNSL and GBM was evaluated using receiver-operating characteristics analysis and area-under-the-curve (AUC) values for the three parameters. RESULTS: The fmax and Dmin values were significantly higher in GBM than in PCNSL (P < 0.01 and P < 0.0001, respectively). In addition, the SUVmax value was significantly lower in GBM than in PCNSL (P < 0.0005). The AUC values for fmax , Dmin , and SUVmax were 0.756, 0.905, and 0.857, respectively. The combination of the fmax and Dmin increased the diagnostic performance (AUC = 0.936) of fmax (P < 0.05), but this value was not significantly different from the values for Dmin (P = 0.30). CONCLUSION: IVIM-MR imaging noninvasively provides useful quantitative information in distinguishing between PCNSL and GBM. J. Magn. Reson. Imaging 2016;44:1256-1261.

Esophagectomy-related thoracic duct injury detected by lymphoscintigraphy with 99mTc-diethylenetriamine pentaacetic acid-human serum albumin: report of a case.

Chylothorax is an uncommon but potentially life-threatening complication of esophagectomy. A 72-year-old man underwent thoracoscopy-assisted subtotal esophagectomy and reconstruction with a gastric tube, through a retrosternal route, after preoperative chemoradiotherapy. Chylothorax was detected after starting enteral feeding on postoperative day (POD) 7. Despite conservative therapy such as fasting, total parenteral nutrition, and octreotide administration, massive fluid drainage continued. On POD 19, lymphoscintigraphy with (99m)Tc-diethylenetriamine pentaacetic acid-human serum albumin (HSA-D) was performed and the site of leakage was detected at the level of the fourth thoracic vertebra. On POD 23, the thoracic duct was ligated, following which the volume of chylothorax decreased. Lymphoscintigraphy 12 days after the reoperation showed no leakage from the thoracic duct. We recommend lymphoscintigraphy with (99m)Tc-HSA-D for locating the chyle leakage site and helping decide about the operative indication.

Brain volume measured by synthetic magnetic resonance imaging in adult moyamoya disease correlates with cerebral blood flow and brain function.

Moyamoya disease (MMD) is characterized by progressive arterial occlusion, causing chronic hemodynamic impairment, which can reduce brain volume. A novel quantitative technique, synthetic magnetic resonance imaging (SyMRI), can evaluate brain volume. This study aimed to investigate whether brain volume measured with SyMRI correlated with cerebral blood flow (CBF) and brain function in adult MMD. In this retrospective study, 18 adult patients with MMD were included. CBF was measured using iodine-123-N-isopropyl-p-iodoamphetamine single photon emission computed tomography. Cerebrovascular reactivity (CVR) to acetazolamide challenge was also evaluated. Brain function was measured using the Wechsler Adult Intelligence Scales (WAIS)-III/IV and the WAIS-R tests. Gray matter (GM), white matter, and myelin-correlated volumes were evaluated in six areas. Resting CBF was positively correlated with GM fractions in the right anterior cerebral arterial and right middle cerebral arterial (MCA) territories. CVR was positively correlated with GM fraction in the right posterior cerebral arterial (PCA) territory. Full-Scale Intelligence Quotient and Verbal Comprehension Index scores were marginally positively correlated with GM fractions in the left PCA territory. Processing Speed Index score was marginally positively correlated with GM fraction in the right MCA territory. The SyMRI-measured territorial GM fraction correlated with CBF and brain function in patients with MMD.

Dynamic chest radiography for pulmonary vascular diseases: clinical applications and correlation with other imaging modalities.

Dynamic chest radiography (DCR) is a novel functional radiographic imaging technique that can be used to visualize pulmonary perfusion without using contrast media. Although it has many advantages and clinical utility, most radiologists are unfamiliar with this technique because of its novelty. This review aims to (1) explain the basic principles of lung perfusion assessment using DCR, (2) discuss the advantages of DCR over other imaging modalities, and (3) review multiple specific clinical applications of DCR for pulmonary vascular diseases and compare them with other imaging modalities.

Discrepant uptake of the radiolabeled norepinephrine analogues hydroxyephedrine (HED) and metaiodobenzylguanidine (MIBG) in rat hearts.

PURPOSE: (11)C-Hydroxyephedrine (HED) and radioiodinated metaiodobenzylguanidine ((123)I/(131)I-MIBG) are catecholamine analogue tracers for sympathetic nerve positron emission tomography/single photon emission computed tomography (PET/SPECT) imaging. In contrast to humans, rat hearts demonstrate high nonneural catecholamine uptake-2 in addition to neural uptake-1, the contributions of which to tracer accumulation are not fully elucidated. METHODS: Wistar rats were studied using the following pretreatments: uptake-1 blockade with desipramine 2 mg/kg IV, both uptake-1 and -2 blockade with phenoxybenzamine 50 mg/kg IV, or control with saline IV. HED or (123)I-MIBG was injected 10 min after pretreatment, and rats were sacrificed 10 min later. Heart to blood tissue count ratio (H/B ratio) was obtained using a gamma counter. To determine regional tracer uptake, dual-tracer autoradiography was performed with HED and (131)I-MIBG in Wistar rats with chronic infarction by transient coronary occlusion and reperfusion and in healthy control rats. Local tracer distributions were analyzed, and the infarcted rats' local tracer distributions were compared with histology. RESULTS: The H/B ratios in control hearts were 34.4 ± 1.7 and 25.5 ± 2.1 for HED and (123)I-MIBG, respectively. Desipramine led to a significant decrease in HED (3.2 ± 0.5, p < 0.0001), while there was no change in (123)I-MIBG (25.5 ± 6.4, p = n.s.). Phenoxybenzamine led to a significant decrease in both HED and (123)I-MIBG (3.5 ± 0.02, 4.3 ± 0.7, p < 0.0001). Only HED showed a subepicardium-subendocardium gradient in healthy control hearts which is consistent with physiological innervation, while (131)I-MIBG was evenly distributed throughout the myocardium. (131)I-MIBG uptake defect closely matched the scar area determined by histology [3.8 ± 2.3% ((131)I-MIBG defect) vs 4.0 ± 2.4% (scar)]. However, the scar area was clearly exceeded by the HED uptake defect (9.1 ± 2.2%, p < 0.001). CONCLUSION: HED uptake showed high specificity to neural uptake-1 in rat hearts. On the other hand, (123)I/(131)I-MIBG demonstrated distinct characters of regional tracer distribution and uptake mechanism that are compatible with significant contribution of nonneural uptake-2.

Relationship between impaired cardiac sympathetic activity and spatial dyssynchrony in patients with non-ischemic heart failure: assessment by MIBG scintigraphy and tagged MRI.

BACKGROUND: Impairment of cardiac sympathetic activity has various detrimental effects on cardiac function. The purpose was to investigate the relationship between left ventricular (LV) dyssynchrony and cardiac sympathetic activity in non-ischemic heart failure (HF). METHODS: Twenty-seven patients with non-ischemic HF were enrolled. Cardiac sympathetic activity was assessed by heart-to-mediastinum ratio (H/M ratio) on (123)I-Metaiodobenzylguanidine scintigraphy. LV dyssynchrony was assessed by cross-correlation analysis of time curves of myocardial circumferential strains delivered from cine-tagging MR images. Temporal dyssynchrony was defined as contraction delay between septal and lateral segments >110 milliseconds. Spatial dyssynchrony was defined as the negative value of the maximum correlation for the two strain time curves. RESULTS: H/M ratio was significantly lower for patients with spatial dyssynchrony compared to patients without (1.8 ± 0.3 vs 2.1 ± 0.3, P < .05). There was no difference between patients with and without temporal dyssynchrony (2.0 ± 0.2 vs 2.0 ± 0.3). The incidence of spatial dyssynchrony was significantly higher in patients with H/M ratio <2.0 than those whose ratios were ≥2.0 (75% vs 20%, P = .001). There was no difference in the incidence of temporal dyssynchrony between the two groups (17% vs 20%). CONCLUSION: Impairment of cardiac sympathetic activity was found to be associated with spatial dyssynchrony in patients with non-ischemic HF.

Utility of FDG PET at the Initial Radioiodine Therapy in Differentiated Thyroid Cancer.

BACKGROUND/AIM: Differentiated thyroid cancer (DTC) has a good prognosis, except in the case of patients with radioiodine therapy (RIT)-refractory cancer. However, since DTC is essentially a slowly progressing cancer, it is usually judged to be a DTC with a poor prognosis after multiple RITs and yearly follow-up with echo, computed tomography (CT), and serum thyroglobulin values. This study investigated whether fluorodeoxyglucose-positron emission tomography/CT (FDG PET/CT) combined with initial RIT could identify early-stage patients with poor prognosis. PATIENTS AND METHODS: We evaluated 100 patients with high-risk DTC who underwent total thyroidectomy and received RIT at our institution. We analyzed the clinical outcomes of patients and 18F-FDG accumulation using univariate and multivariate Cox proportional hazards regression models. RESULTS: The 10-year overall survival (OS) was 87.9%, with no significant difference in OS between 18F-FDG accumulation at pre-total or near-total thyroidectomy (NTT) (p=0.180) and 131I accumulation at initial RIT (p=0.577). However, 18F-FDG positive patients had a significantly worse prognosis than negative patients (p=0.005) at initial RIT. CONCLUSION: 18F-FDG PET/CT plays an important role in both the diagnosis and prognostic prediction of RIT refractory disease in DTC patients. 18F-FDG PET/CT can be a useful tool particularly at the time of initial RIT since the 18F-FDG accumulation enables the screening of high-risk DTC with poor prognosis at a very early time stage.

Clinical Implications of FDG-PET in Pancreatic Ductal Adenocarcinoma Patients Treated with Neoadjuvant Therapy.

PURPOSE: To evaluate the clinical significance of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with pancreatic ductal adenocarcinoma who underwent neoadjuvant therapy. METHODS: Among 285 consecutive patients who underwent pancreatic resection for pancreatic ductal adenocarcinoma between 2015 and 2021, 86 who underwent preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography after completion of neoadjuvant treatment were reviewed. Among preoperative factors, including post-treatment maximum standardized uptake value, predictors of early recurrence and poor prognosis were identified using multivariate analysis for decision making in surgery. RESULTS: Nineteen (22%) patients with pancreatic ductal adenocarcinoma demonstrated high maximum standardized uptake (≥ 4.5). High post-treatment maximum standardized uptake (≥ 4.5) predicted early recurrence within 6 months after surgery and correlated with shorter recurrence-free survival. Elevated post-treatment CA19-9 level (> 37 U/ml) and maximum standardized uptake ≥ 4.5 were independent prognostic factors. Post-treatment, a high maximum standardized uptake value indicated a poorer prognosis than a low maximum standardized uptake value in both patients with elevated CA19-9 and normal CA19-9 levels. The median overall survival in patients with elevated post-treatment CA19-9 and high maximum standardized uptake was only 17 months; 67% experienced early recurrence. Dynamic changes in maximum standardized uptake during neoadjuvant therapy were correlated with pathological response to neoadjuvant therapy, but not with radiological response or change in CA19-9 level. CONCLUSIONS: Post-treatment assessment using maximum standardized uptake value is useful for stratifying patients with pancreatic ductal adenocarcinoma who will benefit from surgery. Instead of subsequent curative resection, additional neoadjuvant therapy should be considered in patients with a persistently high maximum standardized uptake value.

Incremental diagnostic value of SPECT/CT with 131I scintigraphy after radioiodine therapy in patients with well-differentiated thyroid carcinoma.

PURPOSE: To retrospectively determine the incremental diagnostic value of adding single photon emission computed tomography/computed tomography (SPECT/CT) to whole-body scintigraphy with iodine 131 ((131)I) compared with scintigraphy alone after radioiodine therapy in patients with well-differentiated thyroid carcinoma. MATERIALS AND METHODS: This retrospective study was institutional review board approved; written informed consent was waived. The study included 147 patients (94 female, 53 male patients; mean age, 51 years) with well-differentiated thyroid carcinoma treated with radioiodine therapy between October 2009 and August 2010. Whole-body scintigraphy and SPECT/CT were performed on the same day in all patients receiving radioiodine therapy. Each radioactive focus at whole-body scintigraphy was classified as positive or equivocal with respect to thyroid bed, lymph node, and distant metastasis uptake. Differences between whole-body scintigraphy and SPECT/CT findings were assessed with the generalized McNemar test. RESULTS: At SPECT/CT, origin was clearly determined of all five "hot spots" in the thyroid bed (remnant thyroid tissue or metastatic lymph node) that were judged as equivocal at whole-body scintigraphy. Interpretation of 24 (22.2%) of 108 radioactive foci for lymph node metastases was changed with SPECT/CT (P < .0001). One of 85 foci that were thought to be positive findings at whole-body scintigraphy turned out to be a negative finding (false-positive finding), and 13 and seven of 20 equivocal foci at whole-body scintigraphy were positive and negative findings, respectively, after adding SPECT/CT findings. Three false-negative findings at whole-body scintigraphy were corrected with SPECT/CT. For the detection of distant metastasis, the interpretations of 21 (40%) of 52 foci were corrected with SPECT/CT (P < .0001). One of 32 foci thought to be a positive finding at whole-body scintigraphy was a negative finding, and 11 and nine of 20 equivocal foci at whole-body scintigraphy were positive and negative findings, respectively, after SPECT/CT. At a patient-based analysis, SPECT/CT findings helped change the clinical staging in nine (6.1%) of 147 patients and therapeutic planning in three (2.0%) of 147 patients. CONCLUSION: SPECT/CT improved detection and localization of (131)I accumulation in lymph node metastases and distant metastases, compared with whole-body scintigraphy.

Usefulness of semi-quantitative analysis in 123I metaiodobenzylguanidine SPECT/CT for the differentiation of pheochromocytoma and cortical adenoma.

OBJECTIVE: 123I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of pheochromocytomas (PHEOs), but some PHEOs are difficult to differentiate from cortical adenoma (CA) or normal adrenal uptake by visual evaluation alone. A new semi-quantitative analysis using 123I MIBG SPECT/CT is thus expected. Herein, we introduce the tumor-to-liver count ratio (T/L) and the tumor-to-muscle count ratio (T/M). METHODS: We examined the cases of 21 patients with PHEOs (10 males, 11 females; age 24-80, median 61 years) and 23 patients with CA (15 males and 8 females, age 30-78, median 58 years). The visual scoring based on 123I MIBG planar images (planar score) and SPECT images (SPECT score) was used as the conventional evaluation. Using 123I MIBG SPECT/CT findings, we calculated the semi-quantitative values of the count ratio using the maximum or mean count of the tumor and the liver or muscle as the reference organ (T/Lmax, T/Lmean, T/Mmax and T/Mmean). Each evaluation of the PHEOs and CAs was compared, and the diagnosing performance was evaluated based on an ROC analysis. RESULTS: The area under curve (AUC) values were as follows: the planar score, 0.833; SPECT score, 0.813; T/Lmax, 0.986; T/Lmean, 0.975; T/Mmax, 0.955; and T/Mmean, 0.933. The AUC for T/Mmax was significantly higher than those of the planar score, and SPECT score by ROC analysis (p < 0.01 each). CONCLUSION: The semi-quantitative value of 123I MIBG SPECT/CT is more useful than the conventional visual evaluation for differentiating PHEOs from CAs.

Compared to conventional PET/CT scanners, silicon-photomultiplier-based PET/CT scanners show higher arterial 18F-FDG uptake in whole-body 18F-FDG-PET/CT.

OBJECTIVES: To clarify differences in arterial 18F-FDG (fluorodeoxyglucose) uptake between silicon photomultiplier (SiPM)-based and conventional PET/CT scanners, and to compare clinical and phantom results. PATIENTS AND METHODS: Twenty-six patients with lung tumours underwent serial SiPM-based and conventional PET/CT scans on the same day. We compared the target-to-background ratios [TBRsi (SiPM), TBRc (conventional)] and the percentage difference between TBRsi and TBRc (ΔTBR) in the carotid artery, aorta and peripheral arteries. The correlation between ΔTBR and vessel size was also investigated. In the carotid artery, active segment analyses were performed with the threshold (TBR ≥1.6), and we compared each scanner's ratio of active segments and TBR values. We compared the clinical results with the recovery coefficients (RCs). RESULTS: The TBRsi was significantly higher than the TBRc in the carotid artery, aorta and peripheral arteries (1.63 ± 0.22 vs. 1.43 ± 0.22, 1.65 ± 0.19 vs. 1.53 ± 0.15 and 1.37 ± 0.31 vs. 1.11 ± 0.27, mean ± SD, P ≤ 0.0001 for all), and the peripheral arteries showed the highest ΔTBR (24.4 ± 16.8%). The small (10-15 mm) vessels (26.9 ± 15.9%) showed significantly higher ΔTBRs than the larger vessels (7.3 ± 8.5% for 15-20 mm, 8.0 ± 12.8% for ≥20 mm, P < 0.0001 for both). The carotid artery showed significantly higher ratios of active segment (54.5 vs. 20.5%, P < 0.0001) and TBR values (1.85 ± 0.25 vs. 1.76 ± 0.15, P = 0.0006) for TBRsi vs. TBRc. The differences in RCs were similar to those of ΔTBR for each vessel size. CONCLUSIONS: SiPM-based PET/CT scanners showed higher arterial 18F-FDG uptake (especially in vessels <15 mm) than conventional scanners, and the threshold TBR ≥1.6 is not applicable for the carotid artery for SiPM-based PET/CT systems.

123I metaiodobenzylguanidine (MIBG) uptake predicts early relapse of neuroblastoma using semi-quantitative SPECT/CT analysis.

OBJECTIVE: 123I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of neuroblastoma (NB). MIBG uptake is correlated with norepinephrine transporter expression; hence, it is expected that high-MIBG tumors would be more highly differentiated and have a better prognosis than those with lower expression. We have introduced a method of assessing MIBG accumulation semi-quantitatively using SPECT/CT fusion images. The purpose of this study was to evaluate the relationship of 123I MIBG uptake measured by semi-quantitative values of SPECT/CT and early relapse of NB. METHODS: We studied the cases of 11 patients (5 males and 6 females, age 5-65 months, median age 20 months) with histopathologically proven NB between April 2010 and March 2015. The early-relapse group was defined as patients who had relapsed within 3 years after the first 123I MIBG SPECT/CT exam. Other patients were classified as the delay-relapse group. Uptake of MIBG was evaluated using the count ratio of tumor and muscles. T/Mmax and T/Mmean were defined as follows: T/Mmax = max count of tumor/max count of muscle, T/Mmean = mean count of tumor/mean count of muscle. RESULTS: The average T/Mmean values of the early-relapse group and delay-relapse group were 2.65 ± 0.58 and 7.66 ± 2.68, respectively. The T/Mmean values of the early-relapse group were significantly lower than those of delay-relapse group (p < 0.05). The average T/Mmax of the early-relapse group and delay-relapse group were 8.86 ± 3.22 and 16.20 ± 1.97, respectively. There was no significant difference in T/Mmax values between the two groups. CONCLUSIONS: Low 123I MIBG uptake using semi-quantitative SPECT/CT analysis was correlated with early relapse of NB.

Optimal monochromatic color combinations for fusion imaging of FDG-PET and diffusion-weighted MR images.

OBJECTIVE: To investigate the optimal monochromatic color combination for fusion imaging of FDG-PET and diffusion-weighted MR images (DW) regarding lesion conspicuity of each image. METHODS: Six linear monochromatic color-maps of red, blue, green, cyan, magenta, and yellow were assigned to each of the FDG-PET and DW images. Total perceptual color differences of the lesions were calculated based on the lightness and chromaticity measured with the photometer. Visual lesion conspicuity was also compared among the PET-only, DW-only and PET-DW-double positive portions with mean conspicuity scores. Statistical analysis was performed with a one-way analysis of variance and Spearman's rank correlation coefficient. RESULTS: Among all the 12 possible monochromatic color-map combinations, the 3 combinations of red/cyan, magenta/green, and red/green produced the highest conspicuity scores. Total color differences between PET-positive and double-positive portions correlated with conspicuity scores (ρ = 0.2933, p < 0.005). Lightness differences showed a significant negative correlation with conspicuity scores between the PET-only and DWI-only positive portions. Chromaticity differences showed a marginally significant correlation with conspicuity scores between DWI-positive and double-positive portions. CONCLUSIONS: Monochromatic color combinations can facilitate the visual evaluation of FDG-uptake and diffusivity as well as registration accuracy on the FDG-PET/DW fusion images, when red- and green-colored elements are assigned to FDG-PET and DW images, respectively.

A Functional Scoring System Based on Salivary Gland Scintigraphy for Evaluating Salivary Gland Dysfunction Secondary to 131I therapy in Patients with Differentiated Thyroid Carcinoma.

INTRODUCTION: Radioiodine therapy with 131I (131I therapy) after total or near-total thyroidectomy has been established as an effective treatment for Differentiated Thyroid Carcinoma (DTC), but can induce dry mouth symptoms by salivary gland damage and impair the patients' quality of life. AIM: To propose a functional scoring system based on Salivary Gland Scintigraphy (SGS) findings that evaluates development of salivary gland dysfunction secondary to 131I therapy in patients with DTC. MATERIALS AND METHODS: This retrospective study evaluated the records of 279 DTC patients who underwent SGS after one or more round(s) of 131I therapy, using 370 MBqof 99mTc-pertechnetate. The SGS results were assessed using a novel functional scoring system in the Parotid Glands (PGs) and Submandibular Glands (SMGs) according to visual evaluations based on a three-point uptake score, Washout Rate (%WR) score after lemon-juice stimulation, and functional score. The scores were compared among pre treatment, low-dose (<10 GBq), and high-dose (>10 GBq) groups and among pre treatment, symptom-positive, and symptom-negative groups. Risk factors for dry mouth were analyzed by univariate and multivariate logistic regression analyses. RESULTS: Dry mouth symptoms developed in 15.4% of the DTC patients after 131I therapy. The three-point uptake, %WR, and functional scores in both the PG and SMG were statistically significant between low-dose and high-dose groups, and between symptom-positive and symptom-negative groups. The PG/SMG functional scores were independent risk factors for dry mouth (odds ratio, 0.03 and 0.0007 respectively). CONCLUSION: SGS-based PG and SMG functional scores were effective biomarkers to objectively evaluate salivary gland dysfunction, with the high strength of association with dry mouth symptoms.

The Efficiency of Respiratory-gated 18F-FDG PET/CT in Lung Adenocarcinoma: Amplitude-gating Versus Phase-gating Methods.

OBJECTIVES: In positron emission tomography (PET) studies, thoracic movement under free-breathing conditions is a cause of image degradation. Respiratory gating (RG) is commonly used to solve this problem. Two different methods, i.e., phase-gating (PG) and amplitude-gating (AG) PET, are available for respiratory gating. It is important to know the strengths and weaknesses of both methods when selecting an RG method for a given patient. We conducted this study to clarify whether AG or PG is preferable for measuring fluorodeoxyglucose (FDG) accumulation in lung adenocarcinoma and to investigate patient conditions which are most suitable for AG and PG methods. METHODS: A total of 31 patients (11 males, 20 females; average age: 70.1±11.6 yrs) with 44 lung lesions, diagnosed as lung adenocarcinoma between April 2012 and March 2013, were investigated. Whole-body FDG-PET/CT scan was performed with both PG and AG methods in all patients. The maximum standardized uptake value (SUVmax) of PG, AG, and the control data of these two methods were measured, and the increase ratio (IR), calculated as IR(%)= (Post - Pre)/Pre × 100, was calculated. The diameter and position of lung lesions were also analyzed. We defined an 'effective lesion' of PG (or AG) as a lesion which showed a higher IR compared to AG (or PG). 8 (25.8%). RESULTS: The average SUVmax and average IR were 8.99±7.94 and %21.4±25.6 in PG and 7.60±6.70 and %4.0±14.4 in AG, respectively. Although there was no significant difference between the average SUVmax of PG and AG (P=0.09), the average IR of PG was significantly higher than that of AG (P<0.01). The number of PG- and AG-effective lesions was 32 (72.7%) and 12 (28.3%), respectively. There was no significant difference in the average diameter or position of the lesions between the PG- and AG-effective lesions. There were 23 (74.2%) PG-effective and 8 (25.8%) AG-effective patients. No significant difference was observed in sex or age between PG- and AG-effective patients. CONCLUSION: The PG method was more effective for measuring FDG accumulation of lung lesions under free-breathing conditions in comparison with the AG method.