Background Isolated rapid eye movement (REM) sleep behaviour disorder (iRBD) is a prodromal state of clinical α-synucleinopathies such as Parkinson’s disease and Lewy body dementia. The lead-time until conversion is unknown. The most reliable marker of progression is reduced striatal dopamine transporter (DAT) binding, but low availability of imaging facilities limits general use. Our prospective observational study aimed to relate metrics of REM sleep without atonia (RWA)—a hallmark of RBD—to DAT-binding ratios in a large, homogeneous sample of patients with RBD to explore the utility of RWA as a marker of progression in prodromal α-synucleinopathies. Methods DAT single-photon emission CT (SPECT) and video polysomnography (vPSG) were performed in 221 consecutive patients with clinically suspected RBD. Results vPSG confirmed RBD in 176 patients (162 iRBD, 14 phenoconverted, 45 non-synucleinopathies). Specific DAT-binding ratios differed significantly between groups, but showed considerable overlap. Most RWA metrics correlated significantly with DAT-SPECT ratios (eg, Montreal tonic vs most-affected-region: r=−0.525; p<0.001). In patients taking serotonergic/noradrenergic antidepressants or dopaminergic substances or with recent alcohol abuse, correlations were weaker, suggesting a confounding influence, unlike other possible confounders such as beta-blocker use or comorbid sleep apnoea. Conclusions In this large single-centre prospective observational study, we found evidence that DAT-binding ratios in patients with iRBD can be used to describe a continuum in the neurodegenerative process. Overlap with non-synucleinopathies and clinical α-synucleinopathies, however, precludes the use of DAT-binding ratios as a precise diagnostic marker. The parallel course of RWA metrics and DAT-binding ratios suggests in addition to existing data that RWA, part of the routine diagnostic workup in these patients, may represent a marker of progression. Based on our findings, we suggest ranges of RWA values to estimate whether patients are in an early, medium or advanced state within the prodromal phase of α-synucleinopathies, providing them with important information about time until possible conversion.

Ziel/Aim Lungenperfusionsszintigraphie wird in der klinischen Routine zur Prädiktion der postoperativen Lungenfunktion bei den Patienten mit Lungenkarzinomen verwendet. Diese Studie vergleicht die Genauigkeit der planaren Lungenperfusionsszintigraphie (pLPS) und der SPECT/CT-Methode.

Abstract Background MRI has shortcomings in differentiation between tumor tissue and post-therapeutic changes in pretreated brain tumor patients. Patients We assessed 22 static FET-PET/CT-scans of 17 pediatric patients (median age 12 years, range 2–16 years, ependymoma n=4, medulloblastoma n=4, low-grade glioma n=6, high-grade glioma n=3, germ cell tumor n=1, choroid plexus tumor n=1, median follow-up: 112 months) with multimodal treatment. Method FET-PET/CT-scans were analyzed visually by 3 independent nuclear medicine physicians. Additionally quantitative FET-Uptake for each lesion was determined by calculating standardized uptake values (SUVmaxT/SUVmeanB, SUVmeanT/SUVmeanB). Histology or clinical follow-up served as reference. Results Static FET-PET/CT reliably distinguished between tumor tissue and post-therapeutic changes in 16 out of 17 patients. It identified correctly vital tumor tissue in 13 patients and post-therapeutic changes in 3 patients. SUV-based analyses were less sensitive than visual analyses. Except from a choroid plexus carcinoma, all tumor entities showed increased FET-uptake. Discussion Our study comprises a limited number of patients but results corroborate the ability of FET to detect different brain tumor entities in pediatric patients and discriminate between residual/recurrent tumor and post-therapeutic changes. Conclusions We observed a clear benefit from additional static FET-PET/CT-scans when conventional MRI identified equivocal lesions in pretreated pediatric brain tumor patients. These results warrant prospective studies that should include dynamic scans.

Abstract The prevalence of metastatic pheochromocytoma/paraganglioma (PPGL) is reported to be 3% to 36% of all the cases. The five-year overall survival rate of such patients ranges from 40 to 77%. The management of metastatic PPGL is challenging taking into account the fact that the optimal strategies for clinical care beyond surgical resection are not guided yet. Peptide receptor radionuclide therapy (PRRT) using somatostatin analogues is effective in other neuroendocrine tumours, can be indicated in patients with positive scans for the respective radiopharmaceuticals. We report preliminary data of the prospective study aimed to assess the safety and efficacy outcomes of 177Lu-DOTATATE for 6 patients with histologically confirmed PPGLs with metastatic progression after the complete PPGL surgery. The mean age of our cohort was 53 years (range 14–73); an equal number of male and female patients was included. Two of them had germline mutations in RET and SDHB genes, respectively. Radiological response utilized RECIST 1.1 criteria; toxicity was graded according to common terminology criteria for adverse events version 4. PPRT scheme varied between three and four cycles. Partial response (PR) was achieved in one and stable disease (SD) in four 4 patients. One patient had treatment refractory with disease progression and dramatic increase of chromogranin A concentration (+268%). Biochemical response (>50% decrease) of chromogranin A was found in 1/6 patients and of catecholamines in 2/6 patients. No hematological or kidney toxicity grade 3–4 was registered. Median overall survival and median progression-free survival rate will be reported after the end of the study. To date, about 250 PPGL patients have been treated with PRRT. PRRT using 177Lu-DOTA-SSAs has shown promise for treatment of PPGLs with improvement of clinical symptoms and/or disease control in the setting of retrospective small case reports or case series. However, more well-designed prospective studies are required to confirm these findings.

Background Patient preference is pivotal for widespread adoption of tests in clinical practice. Patient preferences for invasive versus other noninvasive tests for coronary artery disease are not known. Purpose To compare patient acceptance and preferences for noninvasive and invasive cardiac imaging in North and South America, Asia, and Europe. Materials and Methods This was a prospective 16-center trial in 381 study participants undergoing coronary CT angiography with stress perfusion, SPECT, and invasive coronary angiography (ICA). Patient preferences were collected by using a previously validated questionnaire translated into eight languages. Responses were converted to ordinal scales and were modeled with generalized linear mixed models. Results In patients in whom at least one test was associated with pain, CT and SPECT showed reduced median pain levels, reported on 0-100 visual analog scales, from 20 for ICA (interquartile range [IQR], 4-50) to 6 for CT (IQR, 0-27.5) and 5 for SPECT (IQR, 0-25) (P < .001). Patients from Asia reported significantly more pain than patients from other continents for ICA (median, 25; IQR, 10-50; P = .01), CT (median, 10; IQR, 0-30; P = .02), and SPECT (median, 7; IQR, 0-28; P = .03). Satisfaction with preparation differed by continent and test (P = .01), with patients from Asia reporting generally lower ratings. Patients from North America had greater percentages of "very high" or "high" satisfaction than patients from other continents for ICA (96% vs 82%, respectively; P < .001) and SPECT (95% vs 79%, respectively; P = .04) but not for CT (89% vs 86%, respectively; P = .70). Among all patients, CT was preferred by 54% of patients, compared with 18% for SPECT and 28% for ICA (P < .001). Conclusion For cardiac imaging, patients generally favored CT angiography with stress perfusion, while study participants from Asia generally reported lowest satisfaction. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Woodard and Nguyen in this issue.

Structural and metabolic abnormalities of the temporal lobe are frequently found in temporal lobe epilepsy (TLE). In the present retrospective study, we investigated whether structural abnormalities evident in magnetic resonance imaging (MRI) and hypometabolism evident in [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) independently influence verbal and nonverbal learning and delayed memory in patients with TLE. Sixty-eight patients with refractory unilateral TLE (35 left TLE, 33 right TLE) were divided into three groups: (1) no evidence of pathology in either MRI or FDG-PET studies (MRI−/PET−, n = 15), (2) temporal FDG-PET determined hypometabolism with normal MRI findings (MRI−/PET+, n = 21), and (3) evidence of temporal abnormalities in both MRI and FDG-PET studies (MRI+/PET+, n = 32). A fourth group (MRI+/PET−, n = 4) was too small for further statistical analysis and could not be included. Patients with MRI+/PET+ showed worse verbal memory than patients with MRI−/PET− (p < 0.01), regardless of side of seizure focus. Verbal memory performance of patients with MRI−/PET+ was located between patients with MRI+/PET+ and MRI−/PET−, although group differences did not achieve statistical significance (ps > 0.1). No group differences were found for nonverbal memory (p = 0.27). Our results may suggest an interactive negative effect of metabolic and structural temporal lobe abnormalities on verbal memory. Still, our results are preliminary and need further validation by studies involving larger patient groups and up-to date quantitative imaging analysis methods.

Purpose To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). Materials and Methods All patients gave written informed consent prior to inclusion in this institutional review board-approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. Results The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P < .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P < .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). Conclusion This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. © RSNA, 2017 Online supplemental material is available for this article.

Purpose Dopamine transporter SPECT with 123I-FP-CIT is registered for detection (or exclusion) of nigrostriatal degeneration to support the etiologic classification of parkinsonian syndromes. In case of uncertainty in the interpretation of SPECT findings or unexpected clinical course, follow-up SPECT might be useful. However, the utility of follow-up FP-CIT SPECT has not yet been clarified. Methods One hundred forty-one patients (65.1 ± 10.4 years) from 3 sites with follow-up FP-CIT SPECT 22.4 ± 13.7 months after baseline SPECT were included. Retrospective visual interpretation of FP-CIT SPECT scans was performed by 2 experienced readers according to the following 7-point score: “normal,” some minor degree of uncertainty due to “mild asymmetry” or mild to moderate “uniform reduction,” “Parkinson disease (PD) reduction type 1/2/3,” and “atypical reduction.” Results Normal FP-CIT SPECT or PD characteristic reduction was confirmed by follow-up SPECT in all cases (n = 58). Among patients with some minor degree of uncertainty at baseline (n = 65), the majority (72%) did now show abnormalities in follow-up SPECT, but 20% showed clear progression suggesting nigrostriatal degeneration. The latter was very rare at age younger than 60 years. The final categorization as normal or neurodegenerative was not affected by the time delay between baseline and follow-up SPECT. Conclusions Follow-up FP-CIT SPECT cannot be generally recommended in case of completely normal baseline SPECT or PD characteristic reduction. It also cannot be recommended in patients younger than 60 years, even in case of some minor degree of uncertainty in the baseline SPECT. There is no evidence to delay follow-up FP-CIT SPECT longer than 12 months.

Aim: Hereditary pheochromocytoma-paraganglioma syndromes are characterized by multiple pheochromocytomas (PCC) and paragangliomas (PGLs), inherited in an autosomal dominant manner. Early detection and removal of tumours may prevent or minimize complications related to mass effects and malignant transformation. Having confirmed the diagnosis, it is important to localize the tumours and reveal their extent preoperatively. This study aimed to introduce 18F-DOPA PET/CT as a highly sensitive non-invasive diagnostic tool for early detection of mass lesions in patients with pheochromocytoma-paraganglioma inherited tumour syndrome and to report about its impact on patient management. Patients, methods: We are currently supervising one of the largest documented families in Germany with genetically determined SDHD gene mutation. We performed 18F-DOPA PET/CT in order to detect tumours in asymptomatic gene carriers and enable subsequent surgical therapy. Results: In seven patients undergoing 12 18F-DOPA PET/CT scans 17 lesions have been detected. Three of these lesions, located in the head and neck region, have had no morphologic correlate in CT and one had also no morphologic correlate in MRI. Of the six histologically analyzed lesions five have been tumors (PGL or PCC) and one has been a nodular hyperplasia. This means the 18F-DOPA PET/CT scan in our study group had a sensitivity of 83%. 18F-DOPA PET/CT investigations lead to change in the management in 5/7 studied patients (70%). Conclusion: The benefits of PET/CT in detection of pheochromocytoma and paraganglioma are well documented, but we are the first to use this technique for screening of a rare hereditary disease (estimated prevalence 0.3/100 000).

PURPOSE:MRI alone has its limitations for target selection in biopsy or resection in newly diagnosed and pretreated pediatric brain tumor patients. (18)F-FET-PET imaging is considered to identify metabolically active tumor tissue and to differentiate it from therapy-associated changes. We retrospectively analyzed our experience with (18)F-FET-PET in targeted surgical interventions for pediatric brain tumors.METHODS:In 26 cases with lesions suspicious of a growing brain tumor on MRI, either newly diagnosed or after antitumoral treatment led to (18)F-FET-PET imaging for target selection prior to stereotactic biopsy, navigated open biopsy or navigated microsurgical tumor resection. Indications for (18)F-FET-PET imaging were visualization of metabolic active tumor tissue within diffuse tumors or pretreated lesions as well as depicting their extent.RESULTS:(18)F-FET-PET integration in surgery was feasible in all patients using stereotaxy or neuronavigation. Sensitivity for tumor detection was 20/24. (18)F-FET-PET was false positive in two pretreated patients.CONCLUSION:(18)F-FET-PET imaging is helpful for target selection and can be integrated in surgical guidance. (18)F-FET-PET image-guided surgical targeting yielded histological diagnosis with decent specificity and high sensitivity in our cohort of pediatric brain tumor patients. Our results warrant further evaluation of (18)F-FET-PET imaging for surgical guidance.

Purpose: Oncologic imaging is a key for successful cancer treatment. While the quality assurance (QA) of image acquisition protocols has already been focussed, QA of reading and reporting offers still room for improvement. The latter was addressed in the context of a prospective multicentre trial on fluoro-deoxyglucose (FDG)-positron-emission tomography (PET)/CT-based chemoradiotherapy for locally advanced non-small cell lung cancer (NSCLC).Material and methods: An expert panel was prospectively installed performing blinded reviews of mediastinal NSCLC involvement in FDG-PET/CT. Due to a high initial reporting inter-observer disagreement, the independent data monitoring committee (IDMC) triggered an interventional harmonisation process, which overall involved 11 experts uttering 6855 blinded diagnostic statements. After assessing the baseline inter-observer agreement (IOA) of a blinded re-review (phase 1), a discussion process led to improved reading criteria (phase 2). Those underwent a validation study (phase 3) and were then implemented into the study routine. After 2 months (phase 4) and 1 year (phase 5), the IOA was reassessed.Results: The initial overall IOA was moderate (kappa 0.52 CT; 0.53 PET). After improvement of reading criteria, the kappa values improved substantially (kappa 0.61 CT; 0.66 PET), which was retained until the late reassessment (kappa 0.71 CT; 0.67 PET). Subjective uncertainty was highly predictive for low IOA.Conclusion: The IOA of an expert panel was significantly improved by a structured interventional harmonisation process which could be a model for future clinical trials. Furthermore, the low IOA in reporting nodal involvement in NSCLC may bear consequences for individual patient care. (C) 2015 Elsevier Ltd. All rights reserved.

BACKGROUND:Establishing the diagnosis of coronary artery disease (CAD) in symptomatic patients allows appropriately allocating preventative measures. Single-photon emission computed tomography (CT)-acquired myocardial perfusion imaging (SPECT-MPI) is frequently used for the evaluation of CAD, but coronary CT angiography (CTA) has emerged as a valid alternative. METHODS AND RESULTS:We compared the accuracy of SPECT-MPI and CTA for the diagnosis of CAD in 391 symptomatic patients who were prospectively enrolled in a multicenter study after clinical referral for cardiac catheterization. The area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of CTA and SPECT-MPI for identifying patients with CAD defined as the presence of ≥1 coronary artery with ≥50% lumen stenosis by quantitative coronary angiography. Sensitivity to identify patients with CAD was greater for CTA than SPECT-MPI (0.92 versus 0.62, respectively; P<0.001), resulting in greater overall accuracy (area under the receiver operating characteristic curve, 0.91 [95% confidence interval, 0.88-0.94] versus 0.69 [0.64-0.74]; P<0.001). Results were similar in patients without previous history of CAD (area under the receiver operating characteristic curve, 0.92 [0.89-0.96] versus 0.67 [0.61-0.73]; P<0.001) and also for the secondary end points of ≥70% stenosis and multivessel disease, as well as subgroups, except for patients with a calcium score of ≥400 and those with high-risk anatomy in whom the overall accuracy was similar because CTA's superior sensitivity was offset by lower specificity in these settings. Radiation doses were 3.9 mSv for CTA and 9.8 for SPECT-MPI (P<0.001). CONCLUSIONS:CTA is more accurate than SPECT-MPI for the diagnosis of CAD as defined by conventional angiography and may be underused for this purpose in symptomatic patients. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT00934037.

Drugs of abuse elicit dopamine release in the ventral striatum, possibly biasing dopamine-driven reinforcement learning towards drug-related reward at the expense of non-drug-related reward. Indeed, in alcohol-dependent patients, reactivity in dopaminergic target areas is shifted from non-drug-related stimuli towards drug-related stimuli. Such 'hijacked' dopamine signals may impair flexible learning from non-drug-related rewards, and thus promote craving for the drug of abuse. Here, we used functional magnetic resonance imaging to measure ventral striatal activation by reward prediction errors (RPEs) during a probabilistic reversal learning task in recently detoxified alcohol-dependent patients and healthy controls (N = 27). All participants also underwent 6-[(18) F]fluoro-DOPA positron emission tomography to assess ventral striatal dopamine synthesis capacity. Neither ventral striatal activation by RPEs nor striatal dopamine synthesis capacity differed between groups. However, ventral striatal coding of RPEs correlated inversely with craving in patients. Furthermore, we found a negative correlation between ventral striatal coding of RPEs and dopamine synthesis capacity in healthy controls, but not in alcohol-dependent patients. Moderator analyses showed that the magnitude of the association between dopamine synthesis capacity and RPE coding depended on the amount of chronic, habitual alcohol intake. Despite the relatively small sample size, a power analysis supports the reported results. Using a multimodal imaging approach, this study suggests that dopaminergic modulation of neural learning signals is disrupted in alcohol dependence in proportion to long-term alcohol intake of patients. Alcohol intake may perpetuate itself by interfering with dopaminergic modulation of neural learning signals in the ventral striatum, thus increasing craving for habitual drug intake.

Increased amino acid uptake has been demonstrated in intracerebral tumours and head and neck carcinomas of squamous cell origin. We investigated the potential impact of using 18F-fluoro-ethyl-tyrosine (18F-FET)-PET/CT in addition to conventional imaging for gross tumour volume (GTV) delineation in stereotactic radiotherapy of skull base tumours. The study population consisted of 14 consecutive patients with cranial base tumours (10 with squamous cell histology, 4 others). All patients underwent a FET-PET/CT examination in addition to contrast-enhanced CT and 11 patients underwent MRI. All tumours and histologic types showed increased FET uptake. The GTV was defined by all voxels showing hyperintensity in MRI or CT (GTVMRI/CT) or enhancement in PET (GTVPET), forming a GTVcomposite that was used for the initial treatment fields. An additional volume of infiltrative growth outside the GTVMRI/CT of about 1.0 ± 2 cm3 (5% of the conventional volume) was demonstrated by FET-PET only (GTVPETplus) with significant enlargement (>10% of GTVMRI/CT) in three patients. From existing data, we found correlation between cellular density and the standardized uptake value (SUV) of FET. We were able to substantially reduce the volume of escalated radiation dose (GTVboost) by 11 ± 2 cm3 (24%) of the conventional volume.

Diagnostic effectiveness of Ioflupane I 123 injection (DaTSCANTM, DaTscanTM, or [123I]FP-CIT or ioflupane [123I]) SPECT imaging, was assessed in patients with clinically uncertain parkinsonian syndrome (CUPS).

A previous study of the DOPA decarboxylase substrate 6-[18F]fluoro-L-DOPA (FDOPA) with positron emission tomography (PET) detected no difference of the net blood-brain transfer rate (Kinapp) between detoxified alcoholic patients and healthy controls. Instead, the study revealed an inverse correlation between Kinapp in left ventral striatum and alcohol craving scores. To resolve the influx and efflux phases of radiolabeled molecules, we independently estimated the unidirectional blood-brain FDOPA clearance rate (K) and the washout rate of [18F]fluorodopamine and its deaminated metabolites (k loss), and we also calculated the total distribution volume of decarboxylated metabolites and unmetabolized FDOPA as a steady-state index of the dopamine storage capacity (Vd) in brain. The craving scores in the 12 alcoholics correlated positively with the rate of loss (kloss) in the left ventral striatum. We conclude that craving is most pronounced in the individuals with relatively rapid dopamine turnover in the left ventral striatum. The blood-brain clearance rate (K), corrected for subsequent loss of radiolabeled molecules from brain, was completely normal throughout the brain of the alcoholics, in whom the volume of distribution (Vd) was found to be significantly lower in the left caudate nucleus. The magnitude of Vd in the left caudate head was reduced by 43% relative to the 16 controls, consistent with a 58% increase of kloss. We interpret the findings as indicating that a trait for rapid dopamine turnover in the ventral striatum subserves craving and reward-dependence, leading to an acquired state of increased dopamine turnover in the dorsal striatum of detoxified alcoholic patients.

Subcortical arteriosclerotic encephalopathy (SAE) can affect the nigrostriatal system and presumably cause vascular parkinsonism (VP). However, in patients with SAE, the differentiation of VP from idiopathic Parkinson’s disease (IPS) is challenging. The aim of the present study was to examine the striatal dopamine transporter (DAT) density in patients with parkinsonism and SAE. Fifteen consecutive patients with parkinsonian symptoms displayed SAE, as detected by magnetic resonance imaging (MRI). Fifteen retrospectively chosen, matched patients with diagnosis of IPS without any abnormalities in MRI served as a reference group. DAT SPECT was performed using the tracer 123I-FP-CIT. Scans were acquired on a triple-head SPECT system (Multispect 3, Siemens) and analysed using the investigator-independent BRASS™ software (HERMES). In the SAE group, a DAT deficit was observed in 9/15 patients. In contrast, all patients from the IPS group showed a reduced DAT binding (p = 0.008). The specific binding ratios (BR) of putamen contralateral to the side of the more affected limb versus occipital lobe were in trend higher in patients with SAE versus patients in the IPS-group (p = 0.053). Indices for putaminal asymmetry (p = 0.036) and asymmetry caudate-to-putamen (p = 0.026) as well as the ratio caudate-to-putamen (p = 0.048) were significantly higher in IPS patients having no SAE. DAT deficit was less pronounced in patients with SAE and parkinsonism than in patients with IPS without any abnormalities in the MRI. A potential role of DAT SPECT in the differential diagnosis of VP and IPS requires more assessments within prospective studies.

Purpose: To investigate the potential impact of Ga-68-DOTATOC positron emission tomography (Ga-68-DOTATOC-PET) in addition to magnetic resonance imaging (MRI) and computed tomography (CT) for retrospectively assessing the gross tumor volume (GTV) delineation of meningiomas of the skull base in patients treated with fractionated stereotactic radiation therapy (FSRT).Methods and Materials: The study population consisted of 48 patients with 54 skull base meningiomas, previously treated with FSRT. After scans were coregistered, the GTVs were first delineated with MRI and CT data (GTV(MRI/CT)) and then by PET (GTV(PET)) data. The overlapping regions of both datasets resulted in the GTV(common), which was enlarged to the GTV(final) by adding volumes defined by only one of the complementary modalities (GTV(MRI/CT-added) or GTV(PET-added)). We then evaluated the contribution of conventional imaging modalities (MRI, CT) and Ga-68-DOTATOC-PET to the GTV(final), which was used for planning purposes.Results: Forty-eight of the 54 skull base lesions in 45 patients showed increased Ga-68-DOTATOC uptake and were further analyzed. The mean GTV(MRI/CT) and GTV(PET) were approximately 21 cm(3) and 25 cm(3), with a common volume of approximately 15 cm(3). PET contributed a mean additional GTV of approximately 1.5 cm(3) to the common volume (16% +/- 34% of the GTV(common)). Approximately 4.5 cm(3) of the GTV(MRI/CT) was excluded from the contribution to the common volume. The resulting mean GTV(final) was significantly smaller than both the GTV(MRI/CT) and the GTV(PET). Compared with the initial GTV(MRI/CT), the addition of Ga-68-DOTATOC-PET resulted in more than 10% modification of the size of the GTV(final) in 32 (67%) meningiomasConclusions: Ga-68-DOTATOC-PET/CT seems to improve the target volume delineation in skull base meningiomas, often leading to a reduction of GTV compared with results from conventional imaging (MRI and CT). (C) 2013 Elsevier Inc.

Increased amino acid uptake has been demonstrated in intracerebral tumours and head and neck carcinomas of squamous cell origin. We investigated the potential impact of using 18F-fluoro-ethyl-tyrosine (18F-FET)-PET/CT in addition to conventional imaging for gross tumour volume (GTV) delineation in stereotactic radiotherapy of skull base tumours. The study population consisted of 14 consecutive patients with cranial base tumours (10 with squamous cell histology, 4 others). All patients underwent a FET-PET/CT examination in addition to contrast-enhanced CT and 11 patients underwent MRI. All tumours and histologic types showed increased FET uptake. The GTV was defined by all voxels showing hyperintensity in MRI or CT (GTVMRI/CT) or enhancement in PET (GTVPET), forming a GTVcomposite that was used for the initial treatment fields. An additional volume of infiltrative growth outside the GTVMRI/CT of about 1.0 ± 2 cm3 (5% of the conventional volume) was demonstrated by FET-PET only (GTVPETplus) with significant enlargement (>10% of GTVMRI/CT) in three patients. From existing data, we found correlation between cellular density and the standardized uptake value (SUV) of FET. We were able to substantially reduce the volume of escalated radiation dose (GTVboost) by 11 ± 2 cm3 (24%) of the conventional volume.