Positron Emission Tomography Group Research Articles

Better Oncological Outcomes After Prostate-specific Membrane Antigen Positron Emission Tomography–guided Salvage Radiotherapy Following Prostatectomy

Background and objectiveUp to 50% of patients with prostate cancer experience prostate-specific antigen (PSA) relapse following primary radical prostatectomy (RP). Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is increasingly being used for staging after RP owing to its high detection rate. Our aim was to compare outcomes for patients who received salvage radiotherapy (sRT) with versus without PSMA PET guidance. MethodsIn this observational case-control study, the control group consisted of 344 patients from the SAKK09/10 trial (sRT without PSMA PET guidance from 2011 to 2014). The treatment group consisted of 1548 patients from a retrospective multicenter cohort (PSMA PET-guided sRT from July 2013 to 2020). Data were collected up to November 2023. Patients with pN1 status at RP, initial cM1 status, cM1 status on PET, or PSA >0.5 ng/ml were excluded. Patients with detectable PSA after RP who were treated with sRT were eligible. We assessed 3-yr biochemical recurrence-free survival (BRFS) and metastasis-free survival (MFS). Key findings and limitationsThe study population of 717 patients comprised a control group (n = 255) with median follow-up of 75 mo and a PSMA PET group (n = 462) with median follow-up of 31 mo. In the PSMA PET cohort, 103 patients (22.3%) had PSMA-positive pelvic lymph nodes (PLNs), 85 (18.4%) received androgen deprivation therapy (ADT), and 104 (22.5%) underwent PLN irradiation. The BRFS rate at 3 yr was 71% (95% confidence interval [CI] 64–78%) for the control group and 77% (95% CI 72–82%) for the PSMA PET group. The PSMA PET group had favorable BRFS at 18–24 mo after sRT (hazard ratio 0.32, 95% CI 0.0.14–0.75; p = 0.01) and a lower rate of lymph node relapse after sRT (standardized mean difference 0.603). The MFS rate at 3 yr was 89.2% (95% CI 84.6–94.1%) for the control group and 91.2% (95% CI 88.1–94.4%) for the PSMA PET group. Conclusions and clinical implicationsOur results suggest a moderate improvement in short-term BRFS if PSMA PET is used to guide sRT. One possible reason is individualized PLN coverage facilitated by PET. MFS was not improved by PSMA PET guidance for sRT. Patients’ summaryFor patients who experience recurrence of prostate cancer after surgical removal of their prostate, salvage radiotherapy (sRT) is a further treatment option. We found that a type of scan called PSMA PET (prostate-specific membrane antigen positron emission tomography) to identify recurrence and guide sRT can improve recurrence-free survival because of better targeting of pelvic lymph nodes that may contain cancer cells.

The role of biofluid markers in predicting near‐term cognitive impairment

AbstractBackgroundAlzheimer’s disease (AD) has been defined as a biological construct that can be determined using in vivo biomarkers. Recent studies confirmed the clinical value of the AT(N) framework when using Aβ and tau positron emission tomography (PET) scans in predicting progression from cognitively unimpaired to MCI. Our study aims to investigate if plasma biomarkers can yield similar predictive performance to PET biomarkers, and to also compare against cerebrospinal fluid (CSF) biomarkersMethodIndividuals from the PREVENT‐AD cohort were included in the study. Participants had Aβ and tau plasma measurements and at least one year of clinical follow‐up thereafter (n = 278). A subset of participants had CSF measurements (n = 102) and/or PET scans (n = 133) also with 1‐year clinical follow‐up. Participants were cognitively unimpaired at the time of all biomarker measurements. MCI diagnoses were made by clinical consensus among expert clinical and research staff blind to plasma, CSF, PET, MRI and APOE genotype. We established thresholds of plasma and CSF Aβ and tau positivity based on >80% specificity in identifying individuals with significant levels of Aβ‐PET (plasma Aβ42/40 = 0.057; plasma pTau181 = 7.53 pg/mL; CSF Aβ42 = 961.37; CSF pTau181 = 66.59 pg/mL). Aβ ([18F]NAV4694) and tau ([18F]AV1451)PET thresholds were defined by the mean plus 2 standard deviations from young participants (Aβ SUVR cut‐off = 1.17; tau SUVR cut‐off = 1.24).Result36.8% (7/19) of the A+T+ plasma group progressed to MCI, 50% (4/8) of the A+T+ CSF group progressed to MCI, and 46.6% (7/15) A+T+ PET group progressed to MCI (Fig. 1).We found differences in MCI progression status between the A+T+ group compared to the A‐T‐ and A+T‐ groups across all biomarkers’ measurements, with the A+T+ group always showing a higher rate of progression than the other two groups (post‐hoc chi‐square analyses; p<0.05).ConclusionAbnormal levels of Aβ and tau plasma biomarkers can help predict near‐ term progression to MCI. When plasma thresholds are derived based on PET data, however, plasma biomarkers have a slightly lower specificity than PET and CSF biomarkers, and both plasma and CSF biomarkers are less sensitive than PET biomarkers.

The role of biofluid markers in predicting near‐term cognitive impairment

AbstractBackgroundAlzheimer’s disease (AD) has been defined as a biological construct that can be determined using in vivo biomarkers. Recent studies confirmed the clinical value of the AT(N) framework when using Aß and tau positron emission tomography (PET) scans in predicting progression from cognitively unimpaired to MCI. Our study aims to investigate if plasma biomarkers can yield similar predictive performance to PET biomarkers, and to also compare against cerebrospinal fluid (CSF) biomarkersMethodIndividuals from the PREVENT‐AD cohort were included in the study. Participants had Aß and tau plasma measurements and at least one year of clinical follow‐up thereafter (n = 278). A subset of participants had CSF measurements (n = 102) and/or PET scans (n = 133) also with 1‐year clinical follow‐up. Participants were cognitively unimpaired at the time of all biomarker measurements. MCI diagnoses were made by clinical consensus among expert clinical and research staff blind to plasma, CSF, PET, MRI and APOE genotype. We established thresholds of plasma and CSF Aß and tau positivity based on >80% specificity in identifying individuals with significant levels of Aß‐PET (plasma Aß42/40 = 0.057; plasma pTau181 = 7.53 pg/mL; CSF Aß42 = 961.37; CSF pTau181 = 66.59 pg/mL). Aß ([18F]NAV4694) and tau ([18F]AV1451)PET thresholds were defined by the mean plus 2 standard deviations from young participants (Aß SUVR cut‐off = 1.17; tau SUVR cut‐off = 1.24).Result36.8% (7/19) of the A+T+ plasma group progressed to MCI, 50% (4/8) of the A+T+ CSF group progressed to MCI, and 46.6% (7/15) A+T+ PET group progressed to MCI (Fig. 1).We found differences in MCI progression status between the A+T+ group compared to the A‐T‐ and A+T‐ groups across all biomarkers’ measurements, with the A+T+ group always showing a higher rate of progression than the other two groups (post‐hoc chi‐square analyses; p<0.05).ConclusionAbnormal levels of Aß and tau plasma biomarkers can help predict near‐ term progression to MCI. When plasma thresholds are derived based on PET data, however, plasma biomarkers have a slightly lower specificity than PET and CSF biomarkers, and both plasma and CSF biomarkers are less sensitive than PET biomarkers.

Blood-brain barrier breakdown is linked to tau pathology and neuronal injury in a differential manner according to amyloid deposition

The blood-brain barrier (BBB) breakdown has been suggested as an early marker for Alzheimer's disease (AD); yet the relationship between BBB breakdown and AD-specific biomarkers based on the amyloid/tau/neurodegeneration framework is not clear. This study investigated the relationship between BBB permeability, AD-specific biomarkers, and cognition in patients with cognitive impairment. In this prospective study, we enrolled 62 participants with mild cognitive impairment or dementia between January 2019 and October 2020. All participants were assessed through cognitive tests, amyloid positron emission tomography (PET), dynamic contrast-enhanced magnetic resonance imaging (MRI) for BBB permeability (Ktrans), cerebrospinal fluid studies for Aβ42/40 ratio, phosphorylated-tau Thr181 protein (p-tau), total tau protein (t-tau), and structural MRI for neurodegeneration. In amyloid PET (+) group, higher cortical Ktrans was associated with lower Aβ40 (r = −0.529 p = 0.003), higher Aβ42/40 ratio (r = 0.533, p = 0.003), lower p-tau (r = −0.452, p = 0.014) and lower hippocampal volume (r = −0.438, p = 0.017). In contrast, cortical Ktrans was positively related to t-tau level. (r = 0.489, p = 0.004) in amyloid PET (−) group. Our results suggest that BBB permeability is related to AD-specific biomarkers, but the relationship can vary by the presence of Aβ plaque accumulation.

Use of 18F-NaF PET in the staging of skeletal metastases of newly diagnosed, high-risk prostate cancer patients: a nationwide cohort study

ObjectiveTo determine whether preoperative staging of high-risk prostate cancer with 18F-sodium-fluoride (18F-NaF) positron emission tomography (PET) reduces the risk of skeletal metastases.DesignNationwide, population-based cohort study using real-world data.SettingThe study used...

The Role of FDG-PET in Staging and Treatment for Stage III NSCLC in Ontario, Canada Between 2009-2017

Fluoro-2-deoxyglucose positron-emission tomography (PET) is now considered standard of care in the staging evaluation for new cases of stage III NSCLC however, there is not level 3 evidence demonstrating efficacy of PET. Using retrospective population-based data, we sought to examine the role and timing that PET scans play in influencing treatment choice, as well as survival in patients treated with chemoradiation (CRT) for stage III NSCLC.A retrospective cohort of patients diagnosed with stage III NSCLC from 2009-2017 in Ontario, Canada were identified from the Institute of Clinical Evaluative Sciences (ICES). Overall survival (OS), using a landmark analysis of 6 months, was explored in the entire cohort (PET versus no PET) as well as in patients who received CRT for stage III disease. Survival time was calculated using Kaplan Meier methods, logistic regression was used to evaluate type of treatment received, and Cox regression was used to evaluate factors prognostic of OS amongst patients who received CRT.A total of 13 796 cases were included in our analysis: 6536 pts underwent PET scanning prior to treatment and 7260 did not. Over time, there was a significantly increased utilization of PET from 12.4% in 2009 to 74.1% in 2017 (P < 0.001). In regards to treatment modality, significantly more pts received curative intent therapy in the PET group including: CRT (1472 vs 939 pts; P < 0.001), and surgery (1483 vs 734 pts; P < 0.001). There was significantly improved OS in the whole cohort with upfront PET vs not with median OS of 17.1 (95% CI = 16.3-17.8) vs 11.2 (10.6-11.9) mos (P < 0.001). In pts specifically receiving CRT, OS was similarly improved in the PET vs no PET subgroups with median OS of 21.7 (19.7-24.2) vs 18.5 (16.8-20.7) mos (P = 0.004). Examining the timing of PET scan and commencement of therapy, no significant difference was found among pts who had their scan ≤28 days prior to treatment (median OS = 16 mos), 29-56 days prior to treatment (17.8 mos), and > 56 days prior to treatment (18.6 mos), (P = 0.38); these results were similar in the CRT only subgroup. On multivariate analysis, the only factors predicting survival in the CRT group were male gender (HR 1.20; 1.08-1.33), increasing age (HR 1.07; 1.04-1.10), surgery as part of trimodality therapy (HR 0.60; 0.52-0.70), and receipt of PET prior to treatment (HR 0.83; 0.72-0.95).Significant differences in treatment received and OS due to receipt of PET may be due to stage migration or unmeasured confounders. However, in a CRT subgroup, receipt of PET was associated with improved OS. Advocating for increased access to PET scans in this patient population is of utmost importance especially now with an additional survival benefit of adjuvant immunotherapy following CRT. The timing of the PET scan relative to initiating treatment did not have an obvious impact on survival, which may be reassuring for centers that may lack the capability to perform timely scans or are experiencing delays due to the COVID pandemic.

Assessing the downstream value of first-line cardiac positron emission tomography (PET) imaging using real world Medicare fee-for-service claims data

BackgroundHigher imaging quality makes cardiac positron emission tomography (PET) desirable for evaluation of suspected coronary artery disease (CAD). High cost of PET imaging may be offset by reduced utilization and/or improved outcomes. MethodsThis retrospective observational study utilized Medicare fee-for-service dataset. Study participants had no CAD diagnosis within 1 year prior to initial imaging. The PET group (PET imaging) and propensity score matched comparison group (single photon emission computed tomography or stress echocardiography) underwent index imaging between January 2014 and December 2016. Outcomes were analyzed using generalized linear models. ResultsAmong 144,503 study subjects, 4619 (3.2%) had PET and 139,884 (96.8%) had conventional imaging. After matching, each group had 4619 patients (mean age 74 years, 59% female). The PET group had lower radiation exposure (3.8 milliSievert less per year, 95% CI − 3.96 to − 3.64, P < .0001) and unstable coronary syndrome (incidence rate ratio (IRR) 0.77, 95% CI 0.64-0.94, P = .008). The PET group experienced more hospital admissions (IRR 1.10, 95% CI 1.06-1.15, P < .0001), more use of percutaneous coronary intervention (IRR 1.24, 95% CI 1.02-1.50, P = 0.03), while similar mortality rate (hazard ratio 0.95, 95% CI 0.78-1.14, P = 0.55). The PET group had higher medical spending ($2358.2 vs $1774.3, difference = $583.9 per patient per month, P < .0001). ConclusionsFirst-line PET imaging was not associated with reduced levels of utilization and spending. Clinical outcomes were mostly similar.

Metastasis-directed Therapy (SBRT) Guided by PET-CT 18F-CHOLINE Versus PET-CT 68Ga-PSMA in Castration-sensitive Oligorecurrent Prostate Cancer: A Comparative Analysis of Effectiveness.

The present analysis aims to compare the impact of 18F-fluorocholine (18F-choline) and gallium-68 prostate-specific membrane antigen (68Ga-PSMA) positron emission tomography (PET)-computed tomography (CT)-guided metastases-directed therapies (MDTs) in patients with castration-sensitive oligorecurrent prostate cancer (PC). Inclusion criteria were: (1) histologically proven prostate adenocarcinoma; (2) evidence of biochemical relapse after primary tumor treatment; (3)≤ 3 hypermetabolic oligorecurrent lesions detected by 18F-choline or 68Ga-PSMA PET-CT; (4) PET-CT imaging performed in a single nuclear medicine department; (5) patients treated with upfront stereotactic body radiotherapy (SBRT) without hormone therapy; and (6) SBRT delivered with a dose per fraction≥ 5 Gy. In the case of oligoprogression (≤ 3 lesions outside the previous RT field) after MTD, a further course of SBRT was proposed; otherwise, androgen deprivation therapy (ADT) was administered. A total of 118 lesions in 88 patients were analyzed. Forty-four (50%) patients underwent 68Ga-PSMA PET-guided SBRT, and the remaining underwent choline PET-based SBRT. The median follow-up was 25 months (range, 5-87 months) for the entire cohort. Overall survival and local control were both 100%. Distant progression occurred in 48 (54.5%) patients, for a median distant progression-free survival of 22.8 months (range, 14.4-28.8 months). The median pre-SBRT prostate-specific antigen was 2.04 ng/mL in the choline PET cohort and 0.58 ng/mL in the PSMA-PET arm. Disease-free survival rates were 63.6% and 34%, respectively, in the 68Ga-PSMA and choline PET group (P= .06). The ADT administration rate was higher after choline-PET-guided SBRT (P= .00) owing to the higher incidence of polymetastatic disease after first-course SBRT compared with 68Ga-PSMA-based SBRT. In the setting of oligorecurrent castration-sensitive PC, PSMA-PET-guided SBRT produced a higher rate of ADT-free patients when compared with the 18F-choline-PET cohort. Randomized trials are advocated.

Preoperative evaluation of residual tumor in patients with endometrial carcinoma by using 18F-FDG PET/CT.

Purpose: To evaluate the value of 18F-FDG positron emission tomography (PET)/computed tomography (CT) for determining the presence of residual tumors after curettage in patients with endometrial cancer.Methods: Preoperative 18F-FDG PET/CT was performed in 90 women with endometrial cancer. PET/CT parameters and clinical characteristics were compared between patients with and without residual tumors. The clinical characteristics of patients with residual tumors that showed low 18F-FDG uptake were also analyzed.Results: Among the 90 patients, 86 had residual tumors. ROC analysis identified a lesion SUVmax value of 5.0 as the optimal cut-off value for predicting whether or not patients had a residual tumor. With the SUVmax cut-off of 5, the sensitivity, specificity, positive predictive value, and negative predictive values for residual tumor prediction were 87.2%, 100%, 100%, and 26.7%, respectively. Univariate analysis showed significant associations between the high PET group (SUVmax > 5) and low PET group (SUVmax ≤ 5), and histologic type (P = 0.043) and tumor size (P < 0.001) in patients with residual tumors. In patients with low-grade and clear cell carcinomas and a tumor size < 1.35 cm, the probability of being in the low-PET group was 47.6%. In such patients, major parts of the residual tumors showed low 18F-FDG uptake, similar to that in patients with no residual tumors.Conclusion: SUVmax was the lone predictive value for the presence of residual tumors after curettage in patients with endometrial cancer. Lesion SUVmax greater than 5 suggested a high possibility of residual tumors. In patients with low-grade and clear cell carcinomas with tumor size < 1.35 cm, residual tumors may present low 18F-FDG uptake, mimicking the metabolic phenotypes of patients without residual tumors.

Status of F-18 fluorodeoxyglucose uptake in normal and hibernating myocardium after glucose and insulin loading

ObjectiveF-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been increasingly used in myocardial viability imaging. In routine PET viability studies, oral glucose and intravenous insulin loading is commonly utilized. In an optimal study, glucose and insulin loading is expected to cause FDG uptake both in hibernating and normal myocardium. However, in routine studies it is not uncommon to see absent or reduced FDG uptake in normal myocardium. In this retrospective study we further analyzed our PET viability images to evaluate FDG uptake status in myocardium under the oral glucose and intravenous insulin loading protocol that we use in our hospital. MethodsPatients who had both myocardial perfusion single photon emission computed tomography (SPECT) and FDG PET cardiac viability studies were selected for analysis. FDG uptake status in normal and abnormal myocardial segments on perfusion SPECT was evaluated. Based on SPECT and PET findings, patients were divided into two main groups and four subgroups. Group 1 included PET viable studies and Group 2 included PET-nonviable studies. Subgroups based on FDG uptake in normal myocardium were 1a and 2a (normal uptake) and 1b and 2b (absent or significantly reduced uptake). ResultsSeventy-one patients met the inclusion criteria. Forty-two patients were PET-viable and 29 were PET-nonviable. In 33 of 71 patients (46.4%) there was absent or significantly reduced FDG uptake in one or more normal myocardial segments, which was identified more in PET-viable than PET-nonviable patients (59.5% vs. 27.5%, p=0.008). This finding was also more frequent in diabetic than nondiabetic patients (53% vs. 31.8%), but the difference was not significant (p=0.160). ConclusionsIn nearly half of our patients, one or more normal myocardial segments showed absent or significantly reduced FDG uptake. This finding, particularly if it is diffuse, could be from suboptimal study, inadequacy of current glucose and insulin loading protocols, or various other patient-related causes affecting FDG uptake both in the normal and hibernating myocardium. In cases with significantly reduced FDG uptake in normal myocardium, PET images should be interpreted cautiously to prevent false-negative results for viability.

Influence of Surveillance PET/CT on Detection of Early Recurrence After Definitive Radiation in Stage III Non–small-cell Lung Cancer

BackgroundThere are few data to support the use of varying imaging modalities in evaluating recurrence in non–small-cell lung cancer (NSCLC). We compared the efficacy of surveillance positron emission tomography (PET)/computed tomography (CT) versus CT scans of the chest in detecting recurrences after definitive radiation for NSCLC. Materials and MethodsWe retrospectively analyzed 200 patients treated between 2000 and 2011 who met the inclusion criteria of stage III NSCLC, completion of definitive radiation treatment, and absence of recurrence within the initial 6 months. These patients were then grouped on the basis of the use of PET/CT imaging during postradiation surveillance. Patients who received ≥ 1 PET/CT scans within 6 months of the end of radiation treatment were placed in the PET group whereas all others were placed in the CT group. We compared survival times from the end of treatment to the date of death or last follow-up using log rank tests. Multivariate analysis was conducted to identify factors associated with decreased survival. ResultsIn the entire cohort, median event-free survival (EFS) was 26.7 months, and median overall survival (OS) was 41.2 months. The CT group had a median EFS of 21.4 months versus 29.4 months for the PET group (P = .59). There was no difference in OS between the CT and PET groups (median OS of 41.2 and 41.3 months, respectively; P = .59). There was also no difference in local recurrence-free survival or distant metastases-free survival between the CT-only and PET/CT groups (P = .92 and P = .30, respectively). Similarly, in multivariate analysis, stratification into the PET group was not associated with improved EFS (hazard ratio [HR], 0.90; 95% confidence interval [CI], 0.61-1.34; P = .60) or OS (HR, 1.2; 95% CI, 0.83-1.7; P = .34). ConclusionsIn stage III NSCLC patients treated with definitive radiation and without early recurrence, PET/CT scan surveillance did not result in decreased time to detection of locoregional or distant recurrence or improved survival.

Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice.

There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[(18)F] fluoro-2-deoxy-d-glucose ((18)F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy (18)F-FDG, 4 Gy γ-rays, 10 mGy (18)F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from (18)F-FDG, with respect to malignancy, is approximately 1. However; when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental.

Incidental thyroid carcinoma by FDG-PET/CT: a study of clinicopathological characteristics.

BackgroundThe rising incidence of incidental thyroid carcinoma (ITC) detected during fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scanning poses a challenge to clinicians. The present study aims to critically evaluate the clinicopathological characteristics of ITC detected by FDG-PET/CT.MethodsAmong the 557 patients managed at our institution, 40 (7.2%) patients were identified as having ITC. Of these, 22 patients had their tumor detected by FDG-PET/CT (PET group) and 11 by ultrasonography (USG group). Additional bedside ultrasonography ± fine-needle aspiration (FNA) was done in all patients at their clinic visit. The clinicopathological characteristics were compared between the PET and USG groups.ResultsThe PET group had significantly more patients with history of nonthyroidal malignancy (P < 0.001). Papillary carcinoma was the most common histological type in both groups. Despite having similar histological and prognostic features including tumor size, tumor multifocality, capsular invasion, extrathyroidal extension, and lymph node metastases, tumor bilaterality (or presence of contralateral tumor focus) was significantly more frequent in the PET than the USG group (P = 0.04). The tumors were also more advanced by the tumor–node–metastasis (TNM) staging system in the PET group (P = 0.021). None of the contralateral tumor foci were evident preoperatively. One patient in the USG group developed metastatic thyroid carcinoma in neck lymph nodes 28 months after thyroid resection.ConclusionITC by FDG-PET/CT had higher incidence of tumor bilaterality than those detected by ultrasonography. Total thyroidectomy should be considered for ITC detected by FDG-PET/CT even for tumor size <10 mm.

Predictive Value of 18F-Fluorodeoxyglucose Uptake by Positron Emission Tomography for Non-Small Cell Lung Cancer Patients Treated with Radical Radiotherapy

The purpose of this study is to assess predictive value of the positron emission tomography (PET) with 18F-fluoro-deoxyglucose (FDG) for recurrence and survival after radiotherapy (RT) for non-small cell lung cancer (NSCLC). One hundred forty-nine patients underwent pretreatment PET (n = 67) or PET/computed tomography (CT) (n = 82) and definitive RT for NSCLC. We evaluated the relationship between the maximum-pixel standardized uptake value (SUV(max)) and clinical tumor features. Univariate Cox proportional hazard analysis (UVA) was used to quantify the risk for local-regional recurrence, distant metastases, and death. Multivariate Cox proportional hazard analysis (MVA) was used to assess the potential independent effect of SUV(max). In the PET group, T1 tumors showed significantly lower SUV(max) than T2, T3, and T4 tumors; in the PET/CT group, T1 tumors showed significantly lower SUV(max) than T3 and T4 tumors. A high SUV(max )was a negative factor for local-regional control (LRC) (p < 0.001), distant metastasis-free survival (DMFS) (p = 0.02), and overall survival (OS) (p = 0.001) on UVA in the PET group. However, the significance decreased to 0.05 for LRC, 0.04 for DMFS, and 0.04 for OS by MVA when tumor size was included in the analysis. A high SUV(max) was not a negative factor for LRC, DMFS, or OS on UVA and MVA in the PET/CT group. In conclusion, assessment of predictive value of SUV(max) for NSCLC requires consideration of primary tumor size, and the evidence is not sufficient to suggest that FDG uptake in a primary NSCLC provides prognostic information.

Accuracy of parathyroid imaging: comparison of planar scintigraphy, spect, spect/ct and c-11 methionine pet for the detection of parathyroid adenomas and glandular hyperplasia

To compare the accuracy of planar scintigraphy, single photon emission computed tomography (SPECT), SPECT-CT, and positron emission tomography (PET) with C-11 methionine for the pre-operative detection of parathyroid adenomas. We retrospectively evaluated the pre-operative studies of 60 patients with primary (n=56) and secondary (n=4) hyperparathyroidism. In 25/60 patients (Group 1), only planar scans were obtained, and additional SPECT and SPECT-CT were carried out in 35/60 patients (Group 2). PET or PET-CT with C-11 methionine was conducted in 8/60 patients (Group 3). The results of the planar scans (Group 1) were true positive in 19/25 patients and false negative in 6/25 patients (sensitivity per patient, 76%). Histopathology confirmed 27 adenomas and two hyperplasia. Planar imaging identified 20/29 of these pathologies, whereas 9/29 were missed (sensitivity per adenoma, 69%). SPECT (Group 2) results were true positive in 34/35 patients and false negative in only one case (sensitivity per patient, 97%). On a lesion-based analysis, 38 adenomas were identified, and two were missed (sensitivity per adenoma, 95%). The sensitivities of SPECT and SPECT-CT were equal; however, SPECT-CT provided superior topographic information. C-11 methionine PET (Group 3) results were true positive in all eight patients. In one case, surgery confirmed two ipsilateral adenomas, only one of which was identified by PET (sensitivity per patient, 100%; per adenoma, 88.9%). SPECT is superior to planar imaging. SPECT-CT has identical sensitivity compared to SPECT alone, but it provides additional topographic information. The sensitivity of PET appears to be even higher compared to SPECT. In the case of negative scintigraphic findings and proven hyperparathyroidism, additional C-11 methionine PET or PET-CT is recommended.

Value of18F–fluoro-l-dopa PET in the Preoperative Localization of Focal Lesions in Congenital Hyperinsulinism

To retrospectively compare fluorine 18 ((18)F) fluoro-L-dopa positron emission tomography (PET) and pancreatic venous sampling (PVS) in the preoperative differentiation of diffuse from focal congenital hyperinsulinism (CHI) and localization of focal lesions. This study was approved by the institutional ethical committee, and informed consent for the research study was obtained from the parents of all subjects. Fifty-one patients evaluated for focal CHI between January 1, 1995, and January 31, 2008, were included. Thirty five underwent PVS evaluation alone, and 16 underwent a PET evaluation alone. The sensitivity values of each technique for the diagnosis and localization of focal lesions were compared in regard to results of surgery and pathologic analyses. In each patient, perioperative treatment was reviewed, and the presence of postoperative hypoglycemia was assessed as evidence of incomplete resection. Comparisons of the sensitivity values and recurrence rates were performed by using the Fisher exact test in regard to the number of patients. Comparisons of median age, weight, or number of biopsies were performed with a two-tailed unpaired Mann-Whitney U test. A difference with P < .05 was considered significant. For PVS and PET groups, there was no error in differentiating focal from diffuse forms. PVS was not completed in four of 35 patients. In 27 (87%) of 31 patients in whom PVS was completed and 13 (81%) of 16 patients in whom PET was completed, preoperative localization of the focal lesion was in accordance with the surgical findings (P = .7). Although not significant, the number of biopsies performed before discovering the focal lesion was higher in the PET group compared with the PVS group (P = .06). Inadequate localization occurred in two (6%) patients in the PVS group and five (31%) patients in the PET group at initial preoperative imaging study; these patients underwent repeat surgery for residual CHI (P = .03). (18)F-fluoro-L-dopa PET is equivalent to PVS in the characterization of CHI but does not provide localization of the lesion as precisely as does PVS.

Impact of preoperative positron emission tomography scans on survival after liver resection for metastatic colorectal cancer

Aim: Positron emission tomography (PET) has been used to detect extrahepatic disease in patients in order to determine their suitability for liver resection from colorectal metastases. Our hypothesis is that PET scanning would result in a better 5‐year survival after liver resection due to better patient selection through downstaging of disease.Methods: Between 1997 and 2005 there were 467 patients undergoing potentially curative liver resections in three cohorts. PET scanning was available to our patients without restriction from 2002. There were 215 patients in the pre‐PET era (Group 1), 188 in the PET era where a PET scan was not performed (Group 2) and 64 patients with preoperative PET scanning (Group 3). Our three cohorts were followed up at 1, 3, 6 and 12 months postoperatively with a median follow up of 24, 21 and 20 months, respectively.Results: The 5‐year survival rate for patients with preoperative PET scanning was 68%. The 5‐year survival rate for patients without preoperative PET scanning was 40% in the PET era and 30% in the pre‐PET era (P = 0.0113). The disease‐free interval was 35% in the PET group and 20% without PET scans at 3 years (P &lt; 0.05).Conclusion: The usage of preoperative PET scanning has led to an improved overall survival because of better patient selection from detection of occult extrahepatic disease missed by traditional staging techniques.

A Functional Genetic Variation of the Serotonin (5-HT) Transporter Affects 5-HT1AReceptor Binding in Humans

In humans, 5-HT1A receptors are implicated in anxiety and depressive disorders and their treatment. However, the physiological and genetic factors controlling 5-HT1A receptor expression are undetermined in health and disease. In this study, the influence of two genetic factors on 5-HT1A receptor expression in the living human brain was assessed using the 5-HT1A-selective positron emission tomography (PET) ligand [11C]WAY 100635. After the genotyping of 140 healthy volunteers to study population frequencies of known single nucleotide polymorphisms (SNPs) in the 5-HT1A receptor gene, the influence of the common SNP [(-1018) C>G] on 5-HT1A receptor expression was examined in a group of 35 healthy individuals scanned with [11C]WAY 100635. In the PET group, we also studied the influence of a common variable number tandem repeat polymorphism [short (S) and long (L) alleles] of the 5-HT transporter (5-HTT) gene on 5-HT1A receptor density. Whereas, the 5-HT1A receptor genotype did not show any significant effects on [11C]WAY 100635 binding, 5-HT1A receptor binding potential values were lower in all brain regions in subjects with 5-HTTLPR short (SS or SL) genotypes than those with long (LL) genotypes. Although the PET groups are necessarily a small sample size for a genetic association study, our results demonstrate for the first time that a functional polymorphism in the 5-HTT gene, but not the 5-HT1A receptor gene, affects 5-HT1A receptor availability in man. The results may offer a plausible physiological mechanism underlying the association between 5-HTTLPR genotype, behavioral traits, and mood states.

DETECTION OF PROSTATE CANCER WITH 11C-METHIONINE POSITRON EMISSION TOMOGRAPHY

We studied the detection of primary prostate cancer with positron emission tomography (PET) using C-labeled methionine (MET) in patients with increased prostate specific antigen (PSA) levels and repeatedly negative biopsies. A total of 20 consecutive patients with increased serum PSA and negative repeat biopsies were included in the study. Patient age ranged from 52 to 75 years (average 65). PSA levels ranged from 3.49 to 28.6 ng/ml (average 9.36). Dynamic PET images were obtained from the prostate region using C-labeled MET. Suspicious accumulations of the tracer were anatomically localized using magnetic resonance images and were used as guidance during the next biopsy. PET was positive in 15 (75%) patients, in 7 of whom (46.7%) the next repeat biopsy verified carcinoma. The overall detection rate was 35% (7 of 20) and 46.7% (7 of 15) in the whole group and in the positive PET group, respectively. All 5 of 5 patients with negative MET PET had negative biopsies. MET PET of the prostate with short dynamic scanning and multicore biopsy is a useful method to ensure a high detection rate of prostate cancer in patients with increased PSA and repeat negative biopsies.

Preoperative Positron Emission Tomographic Viability Assessment and Perioperative and Postoperative Risk in Patients With Advanced Ischemic Heart Disease

Objectives. This study sought to investigate whether determination of tissue viability by means of positron emission tomography (PET) before coronary artery bypass graft surgery (CABG) affects clinical outcome with respect to both in-hospital mortality and 1-year survival rate.Background. Patients with coronary artery disease (CAD) and severe left ventricular (LV) dysfunction are at higher risk for perioperative complications associated with CABG. Therefore, the selection of patients who will benefit from CABG is an important clinical issue.Methods. This study retrospectively evaluated 76 patients with advanced CAD and LV dysfunction (LV ejection fraction ≤0.35) who were considered candidates for CABG. Thirty-five patients were selected for CABG on the basis of clinical presentation and angiographic data (group A), and 34 of 41 patients were selected according to extent of viable tissue determined by PET (group B) in addition to clinical presentation and angiographic data.Results. There were four in-hospital deaths (11.4%) in group A and none in group B (p = 0.04). After 12 months, the survival rate was 79% in group A and 97% in group B (p = 0.01). Postoperatively, group B patients had a less complicated recovery (p = 0.05). They required lower doses of catecholamines (p = 0.002) and demonstrated a significantly decreased incidence of low output syndrome (p = 0.05).Conclusions. This retrospective data analysis suggests that selection of patients with impaired LV function on the basis of extent of viability supplementary to clinical and angiographic data may lead to postoperative recovery with a low early mortality and promising short-term survival. Therefore, viability studies permit selection of patients who are at low risk for serious perioperative complications.