The grasp reflex in patients with idiopathic normal pressure hydrocephalus

OBJECTIVE

To investigate the prevalence and intensity of grasp reflexes and to examine changes in these reflexes after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH).

METHODS

We enrolled 147 patients with probable iNPH. A standard procedure was used to determine the presence of grasp reflexes, and the intensity of these reflexes was assessed using a four-category classification. Clinical rating scales and their correlation with grasp reflexes were also evaluated. Grasp reflexes were reassessed in 72 patients 1 year after surgery.

RESULTS

We found that approximately 50.3% of patients with iNPH exhibited a positive grasp reflex. Among these patients, 69% exhibited bilateral positivity, while the remaining patients showed unilateral positivity. Furthermore, the intensity of the grasp reflex was significantly correlated with the severity of gait and with cognitive, urinary, motor, and behavioural symptoms. Surgical interventions led to a reduction (41.7%) or maintenance (30.6%) of the reflex intensity in 72.3% of iNPH patients. The changes in reflex intensity showed significant positive correlations with changes in the number of steps of the Timed Up and Go test and Trail Making Test-A scores but not with changes in total scores on the iNPH Grading Scale.

CONCLUSION

This retrospective study identified grasp reflexes as a highly prevalent phenomenon in patients with iNPH. These reflexes can assist in evaluating the severity of various symptoms, including cognitive, gait, urinary, motor and emotional symptoms.

Nuclear medicine practice in Japan: a report of the ninth nationwide survey in 2022

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind of the radiopharmaceuticals during the 30 days of June 2022 to all nuclear medicine institutes in Japan. The total numbers of them for the year 2022 were estimated depends on the 1-month data. A total of 1095 institutes responded to the survey, including 364 positron emission tomography (PET) centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1299 in total, with 2.5% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 83.8% and 35.5%, respectively. The number of single-photon tracer studies in 2022 was 1.11 million which means increase in 2.7% in 5 years. Bone scintigraphy was a leading examination (31.0%), followed by myocardial scintigraphy (27.1%) and cerebral perfusion study (23.8%) in order. The percentage of SPECT studies showed an increase from 63.5% in previous survey to 66.8% in this survey. PET centers have also increased from 389 to 412, as compared with the previous one. One hundred and twenty-two PET centers have installed one or two in-house cyclotrons. Increasing trends of the PET studies were observed from 1992 to 2017, the trend changed and PET studies showed 1.5% decrease in 5 years. 18F-FDG accounted for 98.6% (610,497 examinations). PET examinations using 11C-methionine, 13N-NH3 and 11C-PIB have decreased, with 1624, 2146 and 525 examinations, respectively in 2022. The total number of nuclear medicine examination was eventually increased by 1.0%. Therapies for pheochromocytoma or paraganglioma (PPGL) with 131I-MIBG and for neuroendocrine tumor with 177Lu-DOTA-TATE were newly started, however, a total number of targeted radionuclide therapy was decreased by 17.7% because 131I-radioiodine and 223Ra targeted therapies were decreased and supply of some radioisotopes was discontinued. 131I-radioiodine targeted therapy showed a decrease in 5 years (- 15.9%), including 4099 patients for thyroid cancer. The number of out-patient thyroid bed ablation therapy with 1110 MBq of 131I was also decreased to 1015 per year. The number of admission rooms specialized for radionuclide targeted therapy increased from 157 to 160. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer (mCRPC) was 1041 patients. This survey was performed during COVID-19 pandemic, however, total number of nuclear medicine examinations was almost same as previous survey (+ 1.0%). Radionuclide therapies with 131I-MIBG and 177Lu-DOTA-TATE were newly started, and new radionuclide therapy will be available in future, therefore, the development of radionuclide therapy will be continued. We are convinced that this survey report is useful in understanding the current status of the nuclear medicine practice in Japan, and in devising the new strategy to strengthen a role of nuclear medicine.

Imaging findings of arrested pneumatisation and differentiation from other skull base lesions

OBJECTIVES

Arrested pneumatisation (AP) is an anatomic variant of the sphenoid sinus. Since AP remains underrecognised, otolaryngologists and radiologists may mistake AP for a lesion and perform follow-up imaging studies. We investigated the imaging findings of CT, MRI, and F-18 fludeoxyglucose (FDG)-positron emission tomography (PET) for AP, and discussed the differences between AP and other skull base lesions.

METHODS

We reviewed multidetector low CT imaging of 442 patients (285 men and 157 women; age range, 19-93 years; mean age, 67.8 years) who underwent FDG-PET/CT for head and neck tumours between January 2019 and December 2019. The imaging findings of AP were reviewed on CT, MRI, FDG-PET/CT, and compared with those of fibrous dysplasia, chordoma, chondrosarcoma, multiple myeloma, and bone invasion of nasopharyngeal carcinoma.

RESULTS

AP was identified in 22 patients (14 men and 8 women; age range, 24-93 years; mean age, 67.0 years) based on criteria from previous reports. AP manifested with well-circumscribed sclerotic margins on CT, without evidence of expansion. AP showed high-signal intensity on T1-/T2 weighted MRI. FDG-PET revealed non-significant uptake [maximum standardised uptake value (SUVmax): 0.85 (range, 0.4-1.27)] in AP. Contrastingly, skull base lesions showed expansion, poorly circumscribed boundaries without osteosclerotic margins, and moderate-to-severe FDG uptake (SUVmax: 1.8-8.4).

CONCLUSIONS

The characteristic imaging findings of AP, namely non-expansile on CT and non-uptake on FDG-PET, may aid in its differentiation from other skull base lesions.

Type 2 Endoleak Detection After Endovascular Aneurysm Repair: Can Low-Flow Endoleaks Also Be Visualized in Silicon-Photomultiplier-Based Positron Emission Tomography/Computed Tomography Scans?

PURPOSE

To present a novel clinical application of silicon-photomultiplier-based positron emission tomography (SiPM-based PET)/computed tomography (CT), detecting a type II endoleak 5 years after endovascular aneurysm repair (EVAR).

TECHNIQUE

SiPM-based PET/CT scans with a standard whole-body protocol were performed for a 73-year-old man with a past medical history of abdominal aortic aneurysms treated with EVAR and currently under investigation of his duodenal papillary carcinoma. The PET/CT demonstrated 18F-fluorodeoxyglucose (FDG) accumulation outside the stent graft in the native sac of the aneurysm. The site of accumulation corresponded to that of the contrast enhancement depicted in the CT angiography taken 1 month earlier. Another CT scan performed 3 months later revealed enlargement of the aneurysm.

CONCLUSION

SiPM-based PET/CT, with its superior sensitivity and spatial resolution over conventional PET/CT, can detect type II low-flow endoleaks.

CLINICAL IMPACT

Abnormal intra-aneurysmal FDG activity incidentally detected on SiPM-based PET/CT is worthy of attention because it may be indicative of endoleaks. Additional imaging using different modalities should be considered so that the patient would not miss the additional treatment opportunity upon observing sac enlargement. For patients with contraindications for iodine CT contrast media, SiPM-based PET/CT would serve as a suitable alternative.

18 F-FDG PET/CT Imaging Post Heart Transplantation Depicts High Accumulation at Sites of Previous Ventricular Assist Device Insertion

ABSTRACT

A 37-year-old man with previous heart transplantation for dilated cardiomyopathy underwent screening for malignancy under posttransplantation immunosuppression. 18 F-FDG PET/CT revealed uptake in 2 peritoneal sites of the pericardium that corresponded to the insertion sites of a left ventricular assist device that was used before transplantation. Additional abnormal uptake in the right axillary artery, aortic arch, and left femoral artery corresponded to the insertion sites for arterial inflow during cardiopulmonary bypass. Knowledge that FDG accumulation may occur at the insertion sites of an extracorporeal-circulation device enables unnecessary tests to be avoided.

Development and validation of an [18F]FDG-PET/CT radiomic model for predicting progression-free survival for patients with stage II - III thoracic esophageal squamous cell carcinoma who are treated with definitive chemoradiotherapy

BACKGROUND

Radiomics is a method for extracting a large amount of information from images and used to predict treatment outcomes, side effects and diagnosis. In this study, we developed and validated a radiomic model of [¹⁸F]FDG-PET/CT for predicting progression-free survival (PFS) of definitive chemoradiotherapy (dCRT) for patients with esophageal cancer.

MATERIAL AND METHODS

Patients with stage II - III esophageal cancer who underwent [¹⁸F]FDG-PET/CT within 45 days before dCRT between 2005 and 2017 were included. Patients were randomly assigned to a training set (85 patients) and a validation set (45 patients). Radiomic parameters inside the area of standard uptake value ≥ 3 were calculated. The open-source software 3D slicer and Pyradiomics were used for segmentation and calculating radiomic parameters, respectively. Eight hundred sixty radiomic parameters and general information were investigated.In the training set, a radiomic model for PFS was made from the LASSO Cox regression model and Rad-score was calculated. In the validation set, the model was applied to Kaplan-Meier curves. The median value of Rad-score in the training set was used as a cutoff value in the validation set. JMP was used for statistical analysis. RStudio was used for the LASSO Cox regression model. p < 0.05 was defined as significant.

RESULTS

The median follow-up periods were 21.9 months for all patients and 63.4 months for survivors. The 5-year PFS rate was 24.0%. In the training set, the LASSO Cox regression model selects 6 parameters and made a model. The low Rad-score group had significantly better PFS than that the high Rad-score group (p = 0.019). In the validation set, the low Rad-score group had significantly better PFS than that the high Rad-score group (p = 0.040).

CONCLUSIONS

The [¹⁸F]FDG-PET/CT radiomic model could predict PFS for patients with esophageal cancer who received dCRT.

Prediction of the development of delirium after transcatheter aortic valve implantation using preoperative brain perfusion SPECT

Objectives

Delirium is an important prognostic factor in postoperative patients undergoing cardiovascular surgery and intervention, including transcatheter aortic valve implantation (TAVI). However, delirium after transcatheter aortic valve implantation (DAT) is difficult to predict and its pathophysiology is still unclear. We aimed to investigate whether preoperative cerebral blood flow (CBF) is associated with DAT and, if so, whether CBF measurement is useful for predicting DAT.

Methods

We evaluated CBF in 50 consecutive patients before TAVI (84.7±4.5 yrs., 36 females) using ^99mTc ethyl cysteinate dimer single-photon emission computed tomography. Preoperative CBF of the DAT group (N = 12) was compared with that of the non-DAT group (N = 38) using whole brain voxel-wise analysis with SPM12 and region of interest-based analysis with the easy-Z score imaging system. Multivariable logistic regression analysis with the presence of DAT was used to create its prediction model.

Results

The whole brain analysis showed that preoperative CBF in the insula was lower in the DAT than in the non-DAT group (P<0.05, family-wise error correction). Decrease extent ratio in the insula of the DAT group (17.6±11.5%) was also greater relative to that of the non-DAT group (7.0±11.3%) in the region of interest-based analysis (P = 0.007). A model that included preoperative CBF in the insula and conventional indicators (frailty index, short physical performance battery and mini-mental state examination) showed the best predictive power for DAT (AUC 0.882).

Conclusions

These results suggest that preoperative CBF in the insula is associated with DAT and may be useful for its prediction.

High diagnostic accuracy for lymph node metastasis of oral squamous cell carcinoma using PET/CT with a silicon photomultiplier

OBJECTIVE

The higher sensitivity of the new-generation positron emission tomography/computed tomography (PET/CT) with silicon photomultiplier (SiPM) may increase false-positive rates in detecting metastatic lymph nodes (LNs). This study aimed to clarify the usefulness of the SiPM PET scanner in diagnosing LN metastasis of oral squamous cell carcinoma (SCC).

METHODS

We retrospectively reviewed consecutive F-18 fluorodeoxyglucose PET/CT images of 39 SCC patients using SiPM PET and 31 SCC patients using non-SiPM PET. We measured the maximum standardized uptake value (SUV_max) of the LNs on PET images and maximum short-axis diameter on transverse CT images.

RESULTS

The sensitivity and specificity of SiPM PET were 86.2% and 95.6%, respectively (cut-off SUV_max, 4.6). The area under the curve (AUC) of SiPM PET (0.977; 95% confidence interval [CI], 0.958-0.995) was significantly higher than that of non-SiPM PET (0.825; 95% CI 0.717-0.934) (P < 0.01). In a size-limited analysis of diameter, the AUC of SiPM PET (≥ 0.96 for all diameters) was significantly higher than that of non-SiPM PET (tended to decrease as the LN diameter decreased) for the diagnosis of LN metastasis by SUV_max.

CONCLUSION

SiPM PET had higher diagnostic accuracy for LN metastasis of oral SCC than non-SiPM PET, even for small LN metastasis without increasing false-positives.

Post-ISCHEMIA Trial Era: Reconsideration of the Role of Nuclear Cardiology in Patients with Chronic Coronary Artery Disease

The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial has had a great impact on the management of chronic coronary artery disease (CAD). One of the implications of this trial is the importance of close patient follow-up. To improve patient prognosis, evaluation of the residual extent of ischemia after treatment may be important because several studies have shown a close relationship between residual ischemia and cardiac events. For this assessment, myocardial perfusion single-photon emission computed tomography (MPS) has been utilized and is almost the only modality. Among the participants in the ISCHEMIA trial, more than 10% were excluded due to the absence of obstructive CAD. The pathophysiology of ischemia without non-obstructive coronary artery disease (INOCA) is gaining recognition; however, diagnosis is difficult, except for the assessment of myocardial flow reserve (MFR). Myocardial perfusion positron emission tomography (PET) is the most common modality for noninvasive evaluation of MFR; however, its availability in Japan is limited. For a breakthrough in this situation, a novel gamma camera with a cadmium zinc telluride (CZT) semiconductor might be one of the solutions that enables the evaluation of MFR with a commercially available perfusion tracer, similar to PET. Another solution is a novel PET tracer with a longer half-life. Clinical trials with ¹⁸F labeled perfusion agents have been initiated in Japan, and in a few years, delivery of this perfusion tracer will result in more frequent and easier assessment of MFR.

Impact of COVID-19 Pandemic on Cardiovascular Testing in Asia

Background

The coronavirus disease-2019 (COVID-19) pandemic significantly affected management of cardiovascular disease around the world. The effect of the pandemic on volume of cardiovascular diagnostic procedures is not known.

Objectives

This study sought to evaluate the effects of the early phase of the COVID-19 pandemic on cardiovascular diagnostic procedures and safety practices in Asia.

Methods

The International Atomic Energy Agency conducted a worldwide survey to assess changes in cardiovascular procedure volume and safety practices caused by COVID-19. Testing volumes were reported for March 2020 and April 2020 and were compared to those from March 2019. Data from 180 centers across 33 Asian countries were grouped into 4 subregions for comparison.

Results

Procedure volumes decreased by 47% from March 2019 to March 2020, showing recovery from March 2020 to April 2020 in Eastern Asia, particularly in China. The majority of centers cancelled outpatient activities and increased time per study. Practice changes included implementing physical distancing and restricting visitors. Although COVID testing was not commonly performed, it was conducted in one-third of facilities in Eastern Asia. The most severe reductions in procedure volumes were observed in lower-income countries, where volumes decreased 81% from March 2019 to April 2020.

Conclusions

The COVID-19 pandemic in Asia caused significant reductions in cardiovascular diagnostic procedures, particularly in low-income countries. Further studies on effects of COVID-19 on cardiovascular outcomes and changes in care delivery are warranted.

Correlation between preoperative 18F-FDG PET/CT findings and postoperative short-term prognosis in lung cancer patients with idiopathic interstitial pneumonia after lung resection

BACKGROUND

The present study aimed to investigate the correlation between preoperative 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸F-FDG) PET/CT findings and short-term survival in lung cancer patients with idiopathic interstitial pneumonia (IIP).

METHODS

We retrospectively reviewed the data of 425 patients who underwent lung resection for non-small cell lung cancer without preoperative radiation therapy between November 2012 and October 2017. The maximum SUV (SUVmax) in the IIP area except the lung cancer site was measured in each patient.

RESULTS

Thirty-one of the 425 patients (7.3%) showed findings of IIP in chest CT. Five of the 31 patients (16.1%) developed acute exacerbation (AE) after lung resection (AE+ group). Twenty-six of the 31 patients (83.9%) did not develop AE (AE- group). In the AE+ group, ¹⁸F-FDG SUVmax in the IIP area was significantly higher (1.9 ± 0.6 vs. 2.7 ± 0.7, p = 0.02) compared with that in the AE- group. The receiver operating characteristic analysis identified an SUVmax threshold score of 2.55 (p = 0.02) for AE. There was no 90-day mortality in the patients with SUVmax < 2.55 (n = 25). On the other hand, the 90-day mortality rate in patients with SUVmax ≥ 2.55 (n = 6) was 33.3% (2 patients).

CONCLUSIONS

¹⁸F-FDG PET/CT may predict AE after lung resection and could be related to short-term survival in lung cancer patients with IIP. Further investigations are needed to improve the prognosis in patients with high SUVmax in the IIP area.

Echolalia in patients with primary progressive aphasia

OBJECTIVE

This study aimed to examine echolalia and its related symptoms and brain lesions in primary progressive aphasia (PPA).

METHODS

Forty-five patients with PPA were included: 19 nonfluent/agrammatic variant PPA (nfvPPA), 5 semantic variant PPA, 7 logopenic variant PPA, and 14 unclassified PPA patients. We detected echolalia in unstructured conversations. An evaluation of language function and the presence of parkinsonism, grasp reflex, imitation behaviour, and disinhibition were assessed. We also measured regional cerebral blood flow (rCBF) using single-photon emission computed tomography.

RESULTS

Echolalia was observed in 12 nfvPPA and 2 unclassified PPA patients. All patients showed mitigated echolalia. We compared nfvPPA patients with echolalia (echolalia group) to those without echolalia (non-echolalia group). The median age of the echolalia group was significantly lower than that of the non-echolalia group, and the echolalia group showed a significantly worse auditory comprehension performance than the non-echolalia group. In contrast, the performance of repetition tasks was not different between the two groups. The prevalence of imitation behaviour in the echolalia group was significantly higher than that in the non-echolalia group. The rCBFs in the bilateral pre-supplementary motor area and bilateral middle cingulate cortex in the echolalia group were significantly lower than those in the non-echolalia group.

CONCLUSIONS

These findings suggest that echolalia is characteristic of nfvPPA patients with impaired comprehension. Reduced inhibition of the medial frontal cortex with release activity of the anterior perisylvian area account for the emergence of echolalia.

Dose-Dependent Radiation-Induced Myocardial Damage in Esophageal Cancer Treated With Chemoradiotherapy: A Prospective Cardiac Magnetic Resonance Imaging Study

Purpose

The purpose of this prospective study was to evaluate radiation-induced myocardial damage after mediastinal radiation therapy (RT) using late gadolinium-enhancement (LGE) magnetic resonance imaging (MRI).

Methods and Materials

We enrolled 19 patients with esophageal cancer who were expected to have long-term survival by definitive treatment. They underwent delayed contrast-enhanced MRI (19 patients before treatment, 19 patients 6 months after treatment, and 12 patients 1.5 years after treatment). Dose distribution of the left ventricle was made using computed tomography, and the dose volume histogram of the left ventricle was calculated. Myocardial signal intensities in individual MRIs were normalized by the mean values in regions receiving low doses (<5 Gy). Changes in the normalized signal intensities after mediastinal radiation therapy were compared among regions where irradiation doses were 0 to 10 Gy, 10 to 20 Gy, 20 to 30 Gy, 30 to 40 Gy, 40 to 50 Gy, and 50 to 60 Gy, and we investigated whether intensity change was detected in a dose-dependent manner.

Results

The registered patients were treated with concurrent chemoradiotherapy with a median total dose of 60 Gy (50.4-66 Gy). Chemotherapy consisting of cisplatin and 5-fluorouracil was administered. In the population-based dose-response curve, dose-dependent intensity changes progressively increased in regions receiving more than 30 Gy. The averages of relative intensity change at 6 months and 1.5 years after treatment were 1.1% and −1.9% at 20 to 30 Gy and 37.5% and 17.5% at 40 to 50 Gy, respectively. LGE in regions receiving more than 30 Gy was detected in 68% (13/19) of the patients.

Conclusions

A dose-dependent relationship for myocardial signal intensity change was found by using LGE MRI. It may be necessary to reduce the volume of the myocardium receiving more than 30 Gy.

Prognostic value of FDG-PET radiomics with machine learning in pancreatic cancer

Patients with pancreatic cancer have a poor prognosis, therefore identifying particular tumor characteristics associated with prognosis is important. This study aims to investigate the utility of radiomics with machine learning using 18F-fluorodeoxyglucose (FDG)-PET in patients with pancreatic cancer. We enrolled 161 patients with pancreatic cancer underwent pretreatment FDG-PET/CT. The area of the primary tumor was semi-automatically contoured with a threshold of 40% of the maximum standardized uptake value, and 42 PET features were extracted. To identify relevant PET parameters for predicting 1-year survival, Gini index was measured using random forest (RF) classifier. Twenty-three patients were censored within 1 year of follow-up, and the remaining 138 patients were used for the analysis. Among the PET parameters, 10 features showed statistical significance for predicting overall survival. Multivariate analysis using Cox HR regression revealed gray-level zone length matrix (GLZLM) gray-level non-uniformity (GLNU) as the only PET parameter showing statistical significance. In RF model, GLZLM GLNU was the most relevant factor for predicting 1-year survival, followed by total lesion glycolysis (TLG). The combination of GLZLM GLNU and TLG stratified patients into three groups according to risk of poor prognosis. Radiomics with machine learning using FDG-PET in patients with pancreatic cancer provided useful prognostic information.

[Examination of Optimal Window Size and Acquisition Time of Respiratory-gated PET Image: Phantom Study with a SiPM-based PET/CT Scanner]

PURPOSE

This phantom study aimed to determine the optimal acquisition window size for phase-based respiratory gating in silicon photomultiplier (SiPM)-based fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and its acquisition time in respiratory-gated imaging with the optimal window size.

METHODS

Images of a moving NEMA IEC Body Phantom Set^TM with hot spheres were acquired. First, the tumor volume and the maximum standardized uptake value (SUV_max) of images reconstructed using a different window size were evaluated to define the optimal window size. Second, the quality of the images reconstructed using the optimal window size and different acquisition times was evaluated using the detectability score of the 10-mm hot sphere and physical indices.

RESULTS

The volume and the SUV_max of the 10-mm hot sphere were improved when the window size was narrow, and there were no significant differences among images reconstructed using a window size narrower than 20%. To reconstruct an image using the 20% window size, an acquisition time of 5 min was required to visualize the 10-mm hot sphere.

CONCLUSIONS

The optimal window size for phase-based respiratory gating is 20%. Further, an acquisition time of 5 min should be taken for respiratory-gated imaging with the 20% window size on SiPM-based FDG-PET/CT.

18F-FDG PET/CT Imaging of Vasculitis Complicated With Relapsing Polychondritis

We present a case of a 38-year-old woman who complained with cough, fever, and back pain with a weight loss. F-FDG PET/CT to search fever origin revealed uptake in the tracheobronchial and the left auricular cartilage and wall of the thoracic aorta. She underwent biopsy of the left auricle and was diagnosed with relapsing polychondritis (RP) complicating vasculitis. After steroid therapy, FDG PET/CT demonstrated regression of inflammation, showing decreases in the uptakes. Vasculitis should be considered in case of RP with systemic manifestations. Our case demonstrated the utility of FDG PET/CT in evaluation of RP lesions including aortitis.

High detection sensitivity and reliable morphological correlation of PET with a silicon photomultiplier for primary tongue squamous cell carcinoma

OBJECTIVE

A positron emission tomography (PET) scanner using a silicon photomultiplier (SiPM PET) in place of a photomultiplier tube significantly improves the spatial and time resolution. It may also improve the evaluation of smaller lesions compared to conventional (non-SiPM) PET scanners. We compared the maximum standardized uptake value (SUV_max), detection sensitivity, and morphological correlation using magnetic resonance imaging (MRI) for primary tongue squamous cell carcinoma between the SiPM PET and non-SiPM PET scanner.

METHODS

We retrospectively reviewed the F-18 fluorodeoxyglucose (FDG) PET/CT features of tongue squamous cell carcinomas in consecutive, newly diagnosed, and pathologically verified patients. Twenty-five of 46 patients were scanned using SiPM PET scanner and the remaining 21 patients were scanned with a non-SiPM PET scanner. We compared the SUV_max and visual evaluation of primary tumor detectability, and the correlation between the PET-based and MRI-based tumor size (long axis, thickness, and volume). Differences in SUV_max and detection sensitivity for the primary tumor were analyzed using Welch's t test and Fisher's exact test, respectively. Correlations among the PET-based, MRI-based tumor size, and SUV_max were assessed using Spearman's rank correlation coefficient.

RESULTS

SUV_max of both T1/T2 and T3/T4 primary tumors were significantly higher for the SiPM PET (T1/T2 mean SUV_max: 6.6 ± 4.3, T3/T4 mean SUV_max: 18.2 ± 9.8) than that for the non-SiPM PET (T1/T2 mean SUV_max: 3.4 ± 1.4, T3/T4 mean SUV_max: 10.2 ± 4.9) (P < 0.05). While all cases of T3/T4 primary tumors were detected by both PET scanners, the detection sensitivity for T1/T2 primary tumors was significantly higher for the SiPM PET (80%) than that for the non-SiPM PET (36.4%) (P < 0.05). MRI-based tumor size correlated significantly with SiPM PET-based tumor long axis (ρ = 0.74) and volume (ρ = 0.91), but not with the non-SiPM PET-based tumor long axis and volume in T1/T2 primary lesions. Correlation between MRI-based tumor size and SUV_max was significant in both PET scanners; however, no significant difference was observed between the two scanners.

CONCLUSIONS

The SiPM PET provides better detection sensitivity and a reliable morphological correlation for the T1/T2 primary tongue tumors than the non-SiPM PET due to its high performance.

Transcatheter aortic valve implantation and cognitive function in elderly patients with severe aortic stenosis

AIMS

The aim of this study was to examine the mechanisms of cognitive impairment and reversibility in elderly patients with severe aortic stenosis (AS) after transcatheter aortic valve implantation (TAVI) with special reference to cerebral blood flow (CBF).

METHODS AND RESULTS

We examined 15 elderly patients with severe AS (mean age 83.2±4.5 years, 12 female) who underwent TAVI. Before and three months after TAVI, we evaluated cognitive function with the Logical Memory II test (LM II), cardiac output (CO) with echocardiography, and CBF with 99mTc single-photon emission computed tomography (SPECT). LM II score and CO were significantly increased after TAVI compared with baseline (p<0.01 for LM II, p<0.005 for CO). Notably, CBF in the local regions, including that in the right hippocampus, was significantly increased after TAVI (p<0.005 at each voxel). The patients with increased CO after TAVI also showed significantly increased CBF in the right hippocampus compared with those without it (p<0.01). Importantly, CBF in the right hippocampus was positively correlated with LM II scores (p<0.05).

CONCLUSIONS

These results provide the first evidence that TAVI may improve cognitive functions associated with increased cerebral perfusion especially in the hippocampus in elderly patients with severe AS.

Coronary Adventitial and Perivascular Adipose Tissue Inflammation in Patients With Vasospastic Angina

BACKGROUND

Recent studies suggested that perivascular components, such as perivascular adipose tissue (PVAT) and adventitial vasa vasorum (VV), play an important role as a source of various inflammatory mediators in cardiovascular disease.

OBJECTIVES

The authors tested their hypothesis that coronary artery spasm is associated with perivascular inflammation in patients with vasospastic angina (VSA) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT).

METHODS

This study prospectively examined 27 consecutive VSA patients with acetylcholine-induced diffuse spasm in the left anterior descending artery (LAD) and 13 subjects with suspected angina but without organic coronary lesions or coronary spasm. Using CT coronary angiography and electrocardiogram-gated ¹⁸F-FDG PET/CT, coronary PVAT volume and coronary perivascular FDG uptake in the LAD were examined. In addition, adventitial VV formation in the LAD was examined with optical coherence tomography, and Rho-kinase activity was measured in circulating leukocytes.

RESULTS

Patient characteristics were comparable between the 2 groups. CT coronary angiography and ECG-gated ¹⁸F-FDG PET/CT showed that coronary PVAT volume and coronary perivascular FDG uptake significantly increased in the VSA group compared with the non-VSA group. Furthermore, optical coherence tomography showed that adventitial VV formation significantly increased in the VSA group compared with the non-VSA group, as did Rho-kinase activity. Importantly, during the follow-up period with medical treatment, both coronary perivascular FDG uptake and Rho-kinase activity significantly decreased in the VSA group.

CONCLUSIONS

These results provide the first evidence that coronary spasm is associated with inflammation of coronary adventitia and PVAT, where ¹⁸F-FDG PET/CT could be useful for disease activity assessment. (Morphological and Functional Change of Coronary Perivascular Adipose Tissue in Vasospastic Angina [ADIPO-VSA Trial]; UMIN000016675).

A multicenter trial of extracorporeal cardiac shock wave therapy for refractory angina pectoris: report of the highly advanced medical treatment in Japan

We have previously demonstrated that cardiac shock wave therapy (CSWT) effectively improves myocardial ischemia through coronary neovascularization both in a porcine model of chronic myocardial ischemia and in patients with refractory angina pectoris (AP). In this study, we further addressed the efficacy and safety of CSWT in a single-arm multicenter study approved as a highly advanced medical treatment by the Japanese Ministry of Health, Labour and Welfare. Fifty patients with refractory AP [mean age 70.9 ± 12.6 (SD) years, M/F 38/12] without the indications of percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) were enrolled in 4 institutes in Japan. Ischemic myocardial regions in the left ventricle (LV) were identified by drug-induced stress myocardial perfusion imaging (MPI). Shock waves (200 shots/spot at 0.09 mJ/mm²) were applied to 40-60 spots in the ischemic myocardium 3 times in the first week. The patients were followed up for 3 months thereafter. Forty-one patients underwent CSWT and completed the follow-up at 3 months. CSWT markedly improved weekly nitroglycerin use [from 3.5 (IQR 2 to 6) to 0 (IQR 0 to 1)] and the symptoms [Canadian Cardiovascular Society functional class score, from 2 (IQR 2 to 3) to 1 (IQR 1 to 2)] (both P < 0.001). CSWT also significantly improved 6-min walking distance (from 384 ± 91 to 435 ± 122 m, P < 0.05). There were no significant changes in LV ejection fraction evaluated by echocardiography and LV stroke volume evaluated by cardiac magnetic resonance imaging (from 56.3 ± 14.7 to 58.8 ± 12.8%, P = 0.10, and from 52.3 ± 17.4 to 55.6 ± 15.7 mL, P = 0.15, respectively). Percent myocardium ischemia assessed by drug-induced stress MPI tended to be improved only in the treated segments (from 16.0 ± 11.1 to 12.1 ± 16.2%, P = 0.06), although no change was noted in the whole LV. No procedural complications or adverse effects related to the CSWT were noted. These results of the multicenter trial further indicate that CSWT is a useful and safe non-invasive strategy for patients with refractory AP with no options of PCI or CABG.

Whole-body total lesion glycolysis is an independent predictor in patients with esophageal cancer treated with definitive chemoradiotherapy

BACKGROUND AND PURPOSE

To determine whether pretreatment whole-body total lesion glycolysis (TLG_WB) and metabolic tumor volume (MTV_WB) are associated with outcomes in patients with esophageal cancer treated with definitive chemoradiotherapy (dCRT).

MATERIALS AND METHODS

Ninety patients with stage II or III thoracic esophageal cancer who underwent FDG-PET/CT within 45 days before dCRT between 2005 and 2013 were reviewed. MTV and TLG of the primary lesion (MTV_pri and TLG_pri) and the sum of MTV and TLG for all lesions (MTV_WB and TLG_WB) were calculated. Predictors were analyzed using the Cox proportional hazards model.

RESULTS

The median follow-up period was 27.7 months. In multivariate analysis, MTV_WB > median was an unfavorable predictor for OS (p = 0.027, hazard ratio [HR]: 2.15), LC (p = 0.039, HR: 1.98) and PFS (p = 0.041, HR: 1.96). TLG_WB > median was an unfavorable predictor for OS (p = 0.019, HR: 2.26), LC (p = 0.015, HR: 2.36) and PFS (p = 0.014, HR: 2.33). SUV_max was not a predictor, and the HR of TLG_WB was higher than that of MTV_WB for OS, LC and PFS in multivariate analysis.

CONCLUSION

TLG_WB and MTV_WB are independent predictors in patients with esophageal cancer.

Clinical utility of texture analysis of 18F-FDG PET/CT in patients with Stage I lung cancer treated with stereotactic body radiotherapy

We evaluated the reproducibility and predictive value of texture parameters and existing parameters of 18F-FDG PET/CT images in Stage I non-small-cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT). Twenty-six patients with Stage I NSCLC (T1-2N0M0) were retrospectively analyzed. All of the patients underwent an 18F-FDG PET/CT scan before treatment and were treated with SBRT. Each tumor was delineated using PET Edge (MIM Software Inc., Cleveland, OH), and texture parameters were calculated using open-source code CGITA. From 18F-FDG PET/CT images, three conventional parameters, including maximum standardized uptake value (SUV), metabolic tumor volume (MTV) and total lesion glycolysis (TLG), and four texture parameters, including entropy and dissimilarity (derived from a co-occurrence matrix) and high-intensity large-area emphasis (HILAE) and zone percentage (derived from a size-zone matrix) were analyzed. Reproducibility was evaluated using two independent delineations conducted by two observers. The ability to predict local control (LC), progression-free survival (PFS) and overall survival (OS) was tested for each parameter. All of the seven parameters except zone percentage showed good reproducibility, with intraclass correlation coefficient values >0.8. In univariate analysis, only HILAE was a significant predictor for LC. Histology, dose fractionation, and maximum SUV were associated with PFS, and histology and dose fractionation were associated with OS. We showed that texture parameters derived from 18F-FDG PET/CT were reproducible and potentially beneficial for predicting LC in Stage I lung cancer patients treated with SBRT.

Pancreatic solitary fibrous tumor causing ectopic adrenocorticotropic hormone syndrome

Solitary fibrous tumors occasionally present with hypoglycemia because of the excessive release of insulin-like growth factor II. We report the first case of pancreatic solitary fibrous tumor causing ectopic adrenocorticotropic hormone syndrome. An 82-year-old Japanese man presented with lower limb edema, uncontrolled hypertension, hypokalemia, and baseline hypercortisolism. Distal pancreatectomy was performed after the clinical diagnosis of a neuroendocrine tumor with ectopic secretion of adrenocorticotropic hormone. On histological examination, the tumor showed spindle cells in a fascicular arrangement. The diagnosis of the solitary fibrous tumor was confirmed by the identification of the NAB2-STAT6 fusion gene and positive immuno-histochemical staining for STAT6 and CD34. Using quantitative real-time polymerase chain reaction, mRNA that encoded proopiomelanocortin, precursor of adrenocorticotropic hormone, was detected. Proopiomelanocortin production through the demethylation of the promoter region Domain IV was detected. Pancreatic solitary fibrous tumors represent a new cause of ectopic adrenocorticotropic hormone syndrome.

Pitfalls of voxel-based amyloid PET analyses for diagnosis of Alzheimer's disease: artifacts due to non-specific uptake in the white matter and the skull

Two methods are commonly used in brain image voxel-based analyses widely used for dementia work-ups: 3-dimensional stereotactic surface projections (3D-SSP) and statistical parametric mapping (SPM). The methods calculate the Z-scores of the cortical voxels that represent the significance of differences compared to a database of brain images with normal findings, and visualize them as surface brain maps. The methods are considered useful in amyloid positron emission tomography (PET) analyses to detect small amounts of amyloid-β deposits in early-stage Alzheimer's disease (AD), but are not fully validated. We analyzed the (11)C-labeled 2-(2-[2-dimethylaminothiazol-5-yl]ethenyl)-6-(2-[fluoro]ethoxy)benzoxazole (BF-227) amyloid PET imaging of 56 subjects (20 individuals with mild cognitive impairment [MCI], 19 AD patients, and 17 non-demented [ND] volunteers) with 3D-SSP and the easy Z-score imaging system (eZIS) that is an SPM-based method. To clarify these methods' limitations, we visually compared Z-score maps output from the two methods and investigated the causes of discrepancies between them. Discrepancies were found in 27 subjects (9 MCI, 13 AD, and 5 ND). Relatively high white matter uptake was considered to cause higher Z-scores on 3D-SSP in 4 subjects (1 MCI and 3 ND). Meanwhile, in 17 subjects (6 MCI, 9 AD, and 2 ND), Z-score overestimation on eZIS corresponded with high skull uptake and disappeared after removing the skull uptake ("scalping"). Our results suggest that non-specific uptakes in the white matter and skull account for errors in voxel-based amyloid PET analyses. Thus, diagnoses based on 3D-SSP data require checking white matter uptake, and "scalping" is recommended before eZIS analysis.

Assessment of myocardial metabolic disorder associated with mediastinal radiotherapy for esophageal cancer -a pilot study

Background

To evaluate the dose-effect relations for myocardial metabolic disorders after mediastinal radiotherapy (RT) by performing iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy.

Methods

Between 2011 and 2012, we performed I-123 BMIPP scintigraphy for patients with esophageal cancer before and six months after curative mediastinal RT. Single photon emission computed tomography (SPECT) images of pre-RT and post-RT were registered into RT dose distributions. The myocardium was contoured, and the regional RT dose was calculated. Normalization is required to compare pre- and post-RT SPECT images because the uptake pattern is changed due to the breathing level. Normalization was applied on the mean of SPECT counts in regions of the myocardium receiving less than 5 Gy. Relative values in each dose region (interval of 5 Gy) were calculated on the basis of this normalization for each patient. The reduction in the percent of relative values was calculated.

Results

Five patients were enrolled in this study. None of the patients had a past history of cardiac disease. The left ventricle was partially involved in RT fields in all patients. The patients received RT with median total doses of 60-66 Gy for the primary tumor and metastatic lymph nodes. Concomitant chemotherapy consisting of cisplatin or nedaplatin and 5-fluorouracil with RT was performed in 4 patients. All patients had reduced uptake corresponding to RT fields. Dose-effect relations for reduced uptake tended to be observed at 6 months after RT with mean decreases of 8.96% in regions at 10-15 Gy, 12.6% in regions at 20-25 Gy, 15.6% in regions at 30-35 Gy, 19.0% in regions at 40-45 Gy and 16.0% in regions at 50-55 Gy.

Conclusions

Dose-effect relations for myocardial metabolic disorders tended to be observed. We may need to make an effort to reduce high-dose mediastinal RT to the myocardium in RT planning.

Case report: adrenal oncocytoma associated with markedly increased FDG uptake and immunohistochemically positive for GLUT1

Usually, benign tumors are not associated with an increased F-18 fluorodeoxyglucose (F-18 FDG) uptake on positron emission tomography (PET), although some exceptions have been reported in adrenal neoplasms. We present a rare case of adrenocortical oncocytoma associated with markedly increased FDG uptake, demonstrating a maximum standardized uptake value of 46.8. Histological examination demonstrated diffuse proliferation of tumor cells with eosinophilic and granular cytoplasm that were diffusely immunopositive for mitochondria and glucose transport protein 1, with focal and weak immunopositivity for 3β-hydroxysteroid dehydrogenase. Ultrastructural examination also revealed abundant mitochondria in the tumor cells. The tumor was diagnosed as adrenocortical oncocytoma and was considered benign according to Lin-Weiss-Bisceglia criteria. Diagnosis of adrenocortical oncocytoma can pose difficulties during both preoperative radiological and postoperative histopathological investigations.

MRI findings of radiation-induced myocardial damage in patients with oesophageal cancer

AIM

To evaluate radiation-induced myocardial damage after mediastinal radiotherapy using MRI.

MATERIALS AND METHODS

Between May 2010 and April 2011, delayed contrast-enhanced MRI was performed for patients who had maintained a complete response to curative radiotherapy for oesophageal cancer for more than 6 months. The patients received radiotherapy with a median total dose of 66 Gy (60-70 Gy) for the primary tumour and metastatic lymph nodes. Images of MRI were analysed by a 17-segment method recommended by the American Heart Association. A segment included mainly in the 40 Gy dose line was defined as Segment 40 Gy, a segment included mainly in the 60 Gy dose line as Segment 60 Gy, and a segment out of the radiation fields as Segment OUT. The percentage of late gadolinium enhancement (LGE) was examined in those categories. The layer in which LGE was predominantly distributed was evaluated for each patient.

RESULTS

Four hundred and eight segments in 24 patients were analysed. The median interval from completion of radiotherapy to MRI was 23.5 months (range 6-88 months). LGE was detected in 12 of the 24 patients. LGE was detected in 15.38% of Segment 40 Gy cases, 21.21% of Segment 60 Gy cases, and 0% of Segment OUT cases. LGE in mid-myocardial and subendocardial layers was detected in 11 patients and one patient, respectively.

CONCLUSION

LGE suggesting radiation induced myocardial fibrosis was observed by performing delayed contrast-enhanced MRI. Care should be taken when planning radiotherapy to avoid late cardiac damage.

Evaluation of radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid scintigraphy

We evaluated radiation-induced myocardial damage using iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy. Between May 2010 and April 2011 we performed I-123 BMIPP scintigraphy for patients who had maintained complete response to curative radiotherapy (RT) for esophageal cancer for more than six months. We compared the area of the myocardium in the RT fields with that of reduced I-123 BMIPP uptake using a 15-segment model that is based on axial computed tomography (CT) images. We classified the segments into three categories: segments receiving 40 Gy (Segment 40 Gy), segments receiving 60 Gy (Segment 60 Gy) and segments out of the radiation fields (Segment 0 Gy). A segment with reduced uptake in the RT fields was defined as positive. A total of 510 segments in 34 patients were used for analysis. The median interval from completion of RT to I-123 BMIPP scintigraphy was 22 months (range, 6-103 months). The numbers of Segment 0 Gy, Segment 40 Gy and Segment 60 Gy were 324, 133 and 53, respectively. Reduced uptake was detected in 42.9% (57/133) of Segment 40 Gy, 67.9% (36/53) of Segment 60 Gy and 13.3% (43/324) of Segment 0 Gy. The odds ratios of 40 Gy and 60 Gy compared with regions out of the RT fields were 5.2 (95% confidence interval [CI]: 3.7-7.4) and 15.4 (95% CI: 6.9-34.6), respectively. Reduced myocardial I-123 BMIPP uptake in RT fields, suggesting RT-induced myocardial damage, was frequently observed. I-123 BMIPP myocardial scintigraphy may be useful for identifying RT-induced myocardial damage.

Intraductal papillary mucininous neoplasm of the bile ducts: multimodality assessment with pathologic correlation

Mucin-producing intraductal papillary neoplasm (adenocarcinoma/adenoma) in the bile duct is becoming recognized as a specific type of neoplasm. Since, it bears a striking similarity to intraductal papillary mucinous neoplasms of the pancreas with regard to its histopathologic features, the term "intraductal papillary mucinous neoplasms of the bile duct" (IPMN-B) is frequently used, although no definite terminology or definition has been decided by World Health Organization. This neoplasm lacks ovarian-like stroma and communicates with the bile ducts, unlike biliary mucinous cystic neoplasm (MCN). On the other hand, malignant IPMN-B is categorized as an intraductal-growth type of intrahepatic cholangiocarcinoma (ICC). In comparison to other types of ICC, such as the mass-forming type and periductal-infiltrating type that have poor resectability and an unfavorable prognosis, malignant IPMN-B can be resected and demonstrates a more favorable prognosis. Meanwhile, unlike biliary MCN that is usually confined in a closed cyst, IPMN-B can spread along the mucosal surface of the bile ducts, and it should be widely resected. Therefore, multimodality assessment is needed to ensure the correct diagnosis of IPMN-B. We herein review the imaging findings of IPMN-B with pathologic correlation.

Additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms of the pancreas with mural nodules

OBJECTIVES

This study aimed at determining the additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas with mural nodules.

METHODS

This retrospective review of medical records was approved by our institutional review board. The preoperative PET/CT images of 16 non-diabetic patients with surgically proven IPMN, where mural nodules of 3 mm or larger were shown by preoperative contrast-enhanced CT, were retrospectively evaluated. The 16 patients were divided into two groups: 7 patients with benign IPMN [adenoma (n = 1) and borderline tumor (n = 6)] and 9 patients with malignant IPMN [carcinoma in situ (CIS) (n = 8) and invasive carcinoma (n = 1)]. Nuclear medicine physician blinded to the pathologic assessment of malignancy of IPMN set a spherical volume of interest (VOI) over the mural nodules on PET/CT images and recorded the peak standardized uptake value (SUV(max)) in the VOI, referring the contrast-enhanced CT images. Statistical differences in the size of mural nodule, the diameter of main pancreatic duct (MPD), and SUV(max) of the tumors between benign IPMNs and malignant IPMNs were compared using the Mann-Whitney U test. Statistical significance was set at p < 0.05. Additionally, the diagnostic accuracy of FDG PET for the detection of malignancy was calculated.

RESULTS

The SUV(max) of the malignant IPMNs with mural nodules of 3 mm or larger was higher than that of benign IPMNs (2.7 ± 0.6 vs. 1.9 ± 0.3, p < 0.01). Meanwhile, there was no significant difference in mural nodule diameter and MPD diameter between the two groups. FDG PET/CT showed an excellent diagnostic accuracy for the differentiation between malignant and benign IPMNs with mural nodules: the sensitivity, specificity, PPV, NPV, and accuracy in malignant IPMN with mural nodule of FDG PET/CT were 77.8, 100, 100, 77.8, and 87.5 for the cutoff value of 2.3; and 100, 57.1, 75.0, 100, and 81.3 for the cutoff value of 2.0, respectively.

CONCLUSIONS

The result of this study indicates that FDG PET/CT can provide additional information for the differentiation between benign and malignant IPMNs of the pancreas with mural nodules.

Positive correlations between tumor uptake on FDG PET and energy expenditure of patients with esophageal cancer

PURPOSE

Cancer patients are prone to clinical malnutrition; moreover, the energy expenditure in patients with certain cancers is higher than that in healthy individuals, rendering their nutritional management a challenging issue. We hypothesized that 2-deoxy-2-[(18)F]fluoro-D: -glucose (FDG) uptake on positron emission tomography (PET) may be related to the energy expenditure and analyzed the FDG uptake and energy expenditure in esophageal cancer patients to clarify this.

METHODS

Esophageal cancer patients [n = 13, 10 males and 3 females, age 66.5 ± 8.9 (51-82) years] were evaluated for FDG uptake using PET. The resting energy expenditure (REE) and basal energy expenditure (BEE) were calculated using indirect calorimetry and the Harris-Benedict formula, respectively. Regression analyses were performed to compare the parameters of imaging and energy expenditure.

RESULTS

Positive correlations were found between tumor uptake on FDG PET and the parameters of energy expenditure. Among them, the correlations between SUV(max) and the ratio of REE to BEE (REE/BEE, r = 0.59; p = 0.035) and between SUV(max) and the difference between REE and BEE (REE - BEE, r = 0.58; p = 0.036) were moderate and statistically significant. Further, the correlation between tumor uptake expressed as a percentage (%TU) and REE/BEE was mild (r = 0.51) but not significant (p = 0.07), while that between %TU and REE-BEE was weak (r = 0.42) and not significant (p = 0.15).

CONCLUSION

Significant positive correlations between SUV(max) on FDG PET and energy expenditure were noted in our study; we consider that these results may aid in determining the nutritional management for esophageal cancer patients.

Imaging of hypoxic lesions in patients with gliomas by using positron emission tomography with 1-(2-[18F] fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole, a new 18F-labeled 2-nitroimidazole analog

OBJECT

Assessment of hypoxic conditions in brain tumors is important for predicting tumor aggressiveness and treatment response. A new hypoxia imaging agent, 1-(2-[(18)F]fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole (FRP-170), with higher image contrast and faster clearance than preexisting hypoxia tracers for PET, was used to visualize hypoxic tissues in 8 patients with glioma.

METHODS

The FRP-170 was injected and PET imaging was performed 2 hours later in 8 patients, including 3 with glioblastoma multiforme, 2 with oligodendroglioma, and 1 each with diffuse astrocytoma, anaplastic ganglioglioma, and recurrent anaplastic astrocytoma. All 8 patients also underwent MR imaging, and some patients underwent [(11)C]methionine or [(18)F]fluorodeoxyglucose PET, and proton MR spectroscopy for comparison. Tissues obtained at biopsy or radical resection were immunostained with hypoxia-inducible factor-1alpha (HIF-1alpha) antibody for the confirmation of hypoxia, except in the patient with recurrent anaplastic astrocytoma who was treated using Gamma Knife surgery.

RESULTS

The FRP-170 PET images showed marked uptake with upregulation of HIF-1alpha in the 3 glioblastomas multiforme, and moderate uptake in the recurrent anaplastic astrocytoma and one oligodendroglioma, but no uptake in the other tumors. The FRP-170 PET images showed positive correlation with HIF-1alpha immunoreactivity and some correlation with FDG PET and MR imaging enhancement, but no correlation with [(11)C]methionine PET. Imaging with FRP-170 PET seemed to be more sensitive for detecting hypoxia than identifying the lactate peak on proton MR spectroscopy.

CONCLUSIONS

Imaging with FRP-170 PET can visualize hypoxic lesions in patients with glioma, as confirmed by histological examination. This new method can assess tumor hypoxia preoperatively and noninvasively.

Steroid receptor signalling in the brain--lessons learned from molecular imaging

Studies with green fluorescent protein (GFP) have revealed the subcellular distribution of many steroid hormone receptors to be much more dynamic than previously thought. Fluorescence resonance energy transfer (FRET) and fluorescence recovery after photobleaching (FRAP) are powerful techniques with which to examine protein-protein interaction and the mobility of tagged proteins, respectively. FRET analysis revealed that steroid treatment (with corticosterone or testosterone) induces direct interaction of the glucocorticoid receptor (GR) and importin alpha in the cytoplasm and that, shortly after nuclear entry, the GR detaches from importin alpha. The mineralocorticoid receptor (MR) and androgen receptor (AR) show the same trafficking. Upon oestradiol treatment, ERalpha and ERbeta in the same cell are relocalised to form a discrete pattern and are localised in the same discrete cluster (subnuclear foci). FRAP analysis showed that nuclear ERalpha and ERbeta are most dynamic and mobile in the absence of the ligand, and that mobility decreases slightly after ligand treatment. Genomic as well as non-genomic actions of steroid hormones influence the cellular function of target tissues spacio-temporally.

Validation of the use of calibration factors between the iodine concentration and the computed tomography number measured outside the objects for estimation of iodine concentration inside the objects: phantom experiment

PURPOSE

The aim of this study was to validate the use of a calibration factor measured outside the object for estimating the iodine concentration inside the object to improve the accuracy of the quantitative contrast-enhanced computed tomography (CT).

MATERIALS AND METHODS

Several known concentrations (0, 6, 9, and 12 mg I/ml) of iodine contrast material (CM) samples were placed inside and outside cylindrical acrylic phantoms of two sizes and were imaged under various combinations of the tube voltages and currents (kV/mAs-80/200, 100/200, 120/200, 140/200) to obtain K factors. The K factors were compared between the phantoms and among the tube voltages. Each CM concentration was estimated from the CT number using the K factor measured outside the phantom.

RESULTS

The K factors varied between the phantoms or among the tube voltages (P < 0.05). Although there were statistically significant variations in K factors among the different regions in a phantom, the mean variation coefficient was 3%-4%. The mean error of the estimated concentration was -5.5%.

CONCLUSION

The CM concentration should be accurately estimated at the region within a patient's body using the K factor measured at the surface of the body regardless of body size and tube voltage.

Intense FDG Uptake in the Ovary With Painless Torsion

We report a case demonstrating intense FDG uptake in the ovary, which was diagnosed to be a hemorrhage and congestion due to painless torsion. An asymptomatic retropelvic mass was detected in a 51-year-old female by echography. FDG-PET demonstrated intense uptake in the mass, thus suggesting an ovarian tumor. A resection of the tumor was performed, and histopathological examination revealed hemorrhage and congestion in the ovary due to ovarian torsion. An ovarian hemorrhage due to painless torsion should be considered in the differential diagnosis of intrapelvic masses demonstrating high FDG uptake, even in asymptomatic patients.

High-density materials do not always induce artifacts on PET/CT: What is responsible for the difference?

OBJECTIVE

PET/CT often show increased uptake at sites of high-density materials. However, some materials seldom demonstrate increased uptake on PET/CT, such as the materials used in hip prostheses. We hypothesized that the motion of materials may be crucial for such artifacts. Here, we present representative cases, and validate our hypothesis based on the results of phantom studies.

METHODS

A standard cylinder, 20 cm in diameter, was filled with approximately 37 MBq of 18F-based activity, and a pacemaker was attached to the side of the cylinder. This phantom was placed on the bed with the pacemaker side facing the scanner. PET scans were performed using a Biograph LSO DUO. CT scans were performed first for transmission scans, followed by acquisition of emission scans. The phantom was first scanned (protocol 1). The phantom was then moved about 2 cm closer to the distal edge of the bed just after transmission CT scan, and the emission scan was performed (protocol 2).

RESULTS

Homogenous uptake was seen in the cylinder in protocol 1, and there was no visible uptake at the site of the pacemaker. In contrast, a clear hotspot was seen at the site of the pacemaker in protocol 2. The uptake in the cylinder was inhomogeneous; that on the pacemaker side of the cylinder was low, while that on the opposite side was high.

CONCLUSIONS

High-density materials do not show false increased uptake without motion on PET/CT. Motion of these materials surrounded by radioactive organs may play an important role in inducing false increased uptake on PET/CT.