Epileptogenic Zone Localization With 18FDG PET Using a New Dynamic Parametric Analysis.

Introduction: [18F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is part of the regular preoperative work-up in medically refractory epilepsy. As a complement to visual evaluation of PET, statistical parametric maps can help in the detection of the epileptogenic zone (EZ). However, software packages currently available are time-consuming and little intuitive for physicians. We develop a user-friendly software (referred as PET-analysis) for EZ localization in PET studies that allows dynamic real-time statistical parametric analysis. To evaluate its performance, the outcome of PET-analysis was compared with the results obtained by visual assessment and Statistical Parametric Mapping (SPM). Methods: Thirty patients with medically refractory epilepsy who underwent presurgical 18F-FDG PET with good post-operative outcomes were included. The 18F-FDG PET studies were evaluated by visual assessment, with SPM8 and PET-analysis. In SPM, parametric T-maps were thresholded at corrected p < 0.05 and cluster size k = 50 and at uncorrected p < 0.001 and k = 100 (the most used parameters in the literature). Since PET-analysis rapidly processes different threshold combinations, T-maps were thresholded with multiple p-value and different clusters sizes. The presurgical EZ identified by visual assessment, SPM and PET-analysis was compared to the confirmed EZ according to post-surgical follow-up. Results: PET-analysis obtained 66.7% (20/30) of correctly localizing studies, comparable to the 70.0% (21/30) achieved by visual assessment and significantly higher (p < 0.05) than that obtained with the SPM threshold p < 0.001/k = 100, of 36.7% (11/30). Only one study was positive, albeit non-localizing, with the SPM threshold corrected p < 0.05/k = 50. Concordance was substantial for PET-analysis (κ = 0.643) and visual interpretation (κ = 0.622), being fair for SPM (κ = 0.242). Conclusion: Compared to SPM with the fixed standard parameters, PET-analysis may be superior in EZ localization with its easy and rapid processing of different threshold combinations. The results of this initial proof-of-concept study validate the clinical use of PET-analysis as a robust objective complementary tool to visual assessment for EZ localization.

PISCOM: a new procedure for epilepsy combining ictal SPECT and interictal PET.

PURPOSE: We present a modified version of the SISCOM procedure that uses interictal PET instead of interictal SPECT for seizure onset zone localization. We called this new nuclear imaging processing technique PISCOM (PET interictal subtracted ictal SPECT coregistered with MRI). METHODS: We retrospectively studied 23 patients (age range 4-61 years) with medically refractory epilepsy who had undergone MRI, ictal SPECT, interictal SPECT and interictal FDG PET and who had been seizure-free for at least 2 years after surgical treatment. FDG PET images were reprocessed (rFDG PET) to assimilate SPECT features for image subtraction. Interictal SPECT and rFDG PET were compared using statistical parametric mapping (SPM). PISCOM and SISCOM images were evaluated visually and using an automated volume of interest-based analysis. The results of the two studies were compared with each other and with the known surgical resection site. RESULTS: SPM showed no significant differences in cortical activity between SPECT and rFDG PET images. PISCOM and SISCOM showed equivalent results in 17 of 23 patients (74%). The seizure onset zone was successfully identified in 19 patients (83%) by PISCOM and in 17 (74%) by SISCOM: in 15 patients (65%) the two techniques showed concordant successful results. The volume of interest-based analysis showed no significant differences between PISCOM and SISCOM in identifying the extension of the seizure onset zone. However, PISCOM showed a lower amount of indeterminate activity due to propagation, background or artefacts. CONCLUSION: Preliminary findings of this initial proof-of-concept study suggest that perfusion and glucose metabolism in the cerebral cortex can be correlated and that PISCOM may be a valid technique for identification of the seizure onset zone. However, further studies are needed to validate these results.

Diagnostic Accuracy of 18F-FDG PET/CT in Infective Endocarditis and Implantable Cardiac Electronic Device Infection: A Cross-Sectional Study.

Early diagnosis of infective endocarditis (IE) is based on the yielding of blood cultures and echocardiographic findings. However, they have limitations and sometimes the diagnosis is inconclusive, particularly in patients with prosthetic valves (PVs) and implantable cardiac electronic devices (ICEDs). The primary aim of this study was to evaluate the diagnostic accuracy of 18F-FDG PET/CT in patients with suspected IE and ICED infection. METHODS: A prospective study with 80 consecutive patients with suspected IE and ICED infection (65 men and 15 women with a mean age of 68 ± 13 y) between June 2013 and May 2015 was performed in our hospital. The inclusion criteria were clinically suspected IE and ICED infection at the following locations: native valve (NV) (n = 21), PV (n = 29), or ICED (n = 30) (automatic implantable defibrillator [n = 11] or pacemaker [n = 19]). Whole-body 18F-FDG PET/CT with a myocardial uptake suppression protocol with unfractionated heparin was performed in all patients. The final diagnosis of infection was established by the IE Study Group according to the clinical, echocardiographic, and microbiologic findings. RESULTS: A final diagnosis of infection was confirmed in 31 patients: NV (n = 6), PV (n = 12), and ICED (n = 13). Sensitivity, specificity, positive predictive value, and negative predictive value for 18F-FDG PET/CT were 82%, 96%, 94%, and 87%, respectively. 18F-FDG PET/CT was false-negative in all cases with infected NV. 18F-FDG PET/CT was able to reclassify 63 of 70 (90%) patients initially classified as possible IE by modified Duke criteria. In 18 of 70 cases, 18F-FDG PET/CT changed possible to definite IE (26%) and in 45 of 70 cases changed possible to rejected IE (64%). Additionally, 18F-FDG PET/CT identified 8 cases of septic embolism and 3 of colorectal cancer in patients with a final diagnosis of IE. CONCLUSION: 18F-FDG PET/CT proved to be a useful diagnostic tool in suspected IE and ICED infection and should be included in the diagnostic algorithm for early diagnosis. 18F-FDG PET/CT is not useful in the diagnosis of IE in NV but should be also considered in the initial assessment of this complex scenario to rule out extracardiac complications and possible neoplasms.

Correlation between theoretical anatomical patterns of lymphatic drainage and lymphoscintigraphy findings during sentinel node detection in head and neck melanomas.

PURPOSE: In the diagnosis of head and neck melanoma, lymphatic drainage is complex and highly variable. As regional lymph node metastasis is one of the most important prognostic factors, lymphoscintigraphy can help map individual drainage patterns. The aim of this study was to compare the results of lymphoscintigraphy and sentinel lymph node (SLN) detection with theoretical anatomical patterns of lymphatic drainage based on the location of the primary tumour lesion in patients with head and neck melanoma. We also determined the percentage of discrepancies between our lymphoscintigraphy and the theoretical location of nodal drainage predicted by a large lymphoscintigraphic database, in order to explain recurrence and false-negative SLN biopsies. METHODS: In this retrospective study of 152 patients with head and neck melanoma, the locations of the SLNs on lymphoscintigraphy and detected intraoperatively were compared with the lymphatic drainage predicted by on-line software based on a large melanoma database. RESULTS: All patients showed lymphatic drainage and in all patients at least one SLN was identified by lymphoscintigraphy. Of the 152 patients, 4 had a primary lesion in areas that were not described in the Sydney Melanoma Unit database, so agreement could only be evaluated in 148 patients. Agreement between lymphoscintigraphic findings and the theoretical lymphatic drainage predicted by the software was completely concordant in 119 of the 148 patients (80.4 %, 95 % CI 73.3 - 86 %). However, this concordance was partial (some concordant nodes and others not) in 18 patients (12.2 %, 95 % CI 7.8 - 18.4 %). Discordance was complete in 11 patients (7.4 %, 95 % CI 4.2 - 12.8 %). CONCLUSION: In melanoma of the head and neck there is a high correlation between lymphatic drainage found by lymphoscintigraphy and the predicted drainage pattern and basins provided by a large reference database. Due to unpredictable drainage, preoperative lymphoscintigraphy is essential to accurately detect the SLNs in head and neck melanoma.

Rapid calcitriol increase and persistent calcidiol insufficiency in the first 6 months after kidney transplantation.

INTRODUCTION: Vitamin D deficiency or insufficiency is prevalent in kidney transplant recipients. Little is known about post-transplantation changes in vitamin D forms, which are essential for bone health and other health outcomes. The aim was to measure the levels of calcidiol and calcitriol during the first 6 months after kidney transplantation and examine their relation with other bone mineral metabolic parameters. PATIENTS AND METHODS: A prospective study was performed on 98 patients recruited between April 2010 and June 2011. Calcidiol and calcitriol levels were measured at baseline and at days 15, 30, 90, and 180 after kidney transplantation. RESULTS: Serum calcidiol levels remained persistently low: 14.3 (9-22) ng/ml at baseline and 16.3 (10.1-20.6) ng/ml at 6 months (P=0.641). At 6 months, calcidiol levels showed an inverse correlation with simultaneously measured parathyroid hormone levels. Calcidiol showed a trend to be higher in patients transplanted in spring but with no statistically significant difference. Calcitriol levels increased from 17 (13-23.7) pg/ml at baseline to 24 (16-32) pg/ml (P=0.002) in the first 2 weeks after transplantation and reached 37 (25-50) pg/ml (P=0.000) after 6 months. During the follow-up, calcitriol levels showed a significant inverse correlation with baseline fibroblast growth factor-23 levels. At month 6, calcitriol levels were inversely correlated with baseline fibroblast growth factor-23 levels and directly correlated with calcidiol levels. CONCLUSION: In most patients, calcidiol levels remain low 6 months after kidney transplantation, whereas calcitriol levels rapidly return to normal. Lower calcidiol blood levels promoted lower calcitriol blood levels and higher parathyroid hormone concentrations.

Changes in bone mineral metabolism parameters, including FGF23, after discontinuing cinacalcet at kidney transplantation.

Little is known about the effects of the administration of cinacalcet in dialytic patients who are scheduled for kidney transplantation, and in particular about the changes in FGF23 and other mineral metabolism parameters after surgery compared with recipients not on cinacalcet at kidney transplantation. We performed a prospective observational cohort study with recruitment of consecutive kidney transplant recipients at our institution. Patients were classified according to whether they were under treatment with cinacalcet before transplantation. Bone mineral metabolism parameters, including C-terminal FGF23, were measured at baseline, on day 15, and at 1, 3, and 6 months after transplantation. In previously cinacalcet-treated patients, cinacalcet therapy was discontinued on the day of surgery and was not restarted after transplantation. A total of 48 kidney transplant recipients, 20 on cinacalcet at surgery and 28 cinacalcet non-treated patients, completed the follow-up. Serum phosphate declined significantly in the first 15 days after transplantation with no differences between the two groups, whereas cinacalcet-treated patients showed higher FGF23 levels, although not significant. After transplantation, PTH and serum calcium were significantly higher in cinacalcet-treated patients. We conclude that patients receiving cinacalcet on dialysis presented similar serum phosphate levels but higher PTH and serum calcium levels during the initial six months after kidney transplantation than cinacalcet non-treated patients. The group previously treated with cinacalcet before transplantation showed higher FGF23 levels without significant differences, so further studies should investigate its relevance in the management of these patients.

Prospective comparison of whole-body (18)F-FDG PET/CT and MRI of the spine in the diagnosis of haematogenous spondylodiscitis.

PURPOSE: To prospectively compare (18)F-FDG PET/CT and MRI in the diagnosis of haematogenous spondylodiscitis METHODS: The study included 26 patients (12 women, 14 men; mean age 59 ± 17 years) with clinical symptoms of infection of the spine. Patients who had had prior spinal surgery or any type of antibiotic therapy in the previous 3 months were excluded from the study. Whole-body PET/CT 60 min after injection of 4.07 MBq/kg of (18)F-FDG and an MRI scan of the spine was performed in all patients. SUVmax in an area surrounding the lesions with the suspicion of infection as well as a background SUVmean in a preserved area of the spine were calculated for quantification. Infection was diagnosed by microbiological documentation in cultures of image-guided spinal puncture fluid or blood. Infection was excluded if symptoms were absent without antimicrobial therapy during a follow-up of at least 6 months. RESULTS: Spondylodiscitis was confirmed in 18 of the 26 patients. Staphylococcus aureus was found in 8 patients, Mycobacterium tuberculosis in 4, Escherichia coli in 2 and other pathogens in 4. Of the remaining 8 patients, the diagnoses were degenerative spondyloarthropathy in 5 and vertebral fracture in 3. The sensitivity, specificity, and positive and negative predictive value were 83%, 88%, 94% and 70% for (18)F-FDG PET/CT, and 94%, 38%, 77% and 75% for MRI, respectively. The accuracies of (18)F-FDG PET/CT and MRI were similar (84% and 81%, respectively). The combination of (18)F-FDG PET/CT and MRI detected the infection in 100% of the patients with spondylodiscitis. (18)F-FDG uptake, quantified in terms of SUVmax corrected by the background SUVmean, was significantly higher in patients with spondylodiscitis than in those without infection (p < 0.001). CONCLUSION: Due to its high specificity, (18)F-FDG PET/CT should be considered as a first-line imaging procedure in the diagnosis of spondylodiscitis. Quantification of uptake in terms of SUVmax was able to discriminate infection of the spine from other processes in this series of patients.

Is there a role for PET/CT with esophagogastric junction adenocarcinoma?

The value of 18F-FDG PET/CT in the initial diagnosis and in the locoregional staging of esophagogastric junction adenocarcinoma is not fully established. However, 18F-FDG PET/CT is widely accepted as the best modality for identification of suspected metastases in staging of the disease. Results published in the literature suggest that 18F-FDG PET/CT may provide useful information for response assessment to neoadjuvancy and to differentiate responding and nonresponding tumors. We review the potential role of 18F-FDG PET/CT imaging in staging, restaging, and prognostic value after chemoradiation therapy in esophagogastric junction adenocarcinoma.

Clinical Role of Subtraction Ictal SPECT Coregistered to MR Imaging and (18)F-FDG PET in Pediatric Epilepsy.

UNLABELLED: A precise assessment of the drug-resistant epileptic pediatric population for surgical candidacy is often challenging, and to date there are no evidence-based guidelines for presurgical identification of the epileptogenic zone. To evaluate the usefulness of radionuclide imaging techniques for presurgical evaluation of epileptic pediatric patients, we compared the results of video-electroencephalography (EEG), brain MR imaging, interictal SPECT, ictal SPECT, subtraction ictal SPECT coregistered to MR imaging (SISCOM), and interictal PET with (18)F-FDG. METHODS: Fifty-four children with drug-resistant epilepsy who had undergone video-EEG monitoring, brain MR imaging, interictal and ictal brain perfusion SPECT, SISCOM, and (18)F-FDG PET were included in this study. All abnormal findings revealed by these neuroimaging techniques were compared with the presumed location of the epileptogenic zone (PEZ) as determined by video-EEG and clinical data. The proportion of localizing studies for each technique was statistically compared. In the 18 patients who underwent resective brain surgery, neuroimaging results were compared with histopathology results and surgical outcome. RESULTS: SISCOM and (18)F-FDG PET concordance with the PEZ was significantly higher than MR imaging (P < 0.05). MR imaging showed localizing results in 21 of 54 cases (39%), SISCOM in 36 of 54 cases (67%), and (18)F-FDG PET in 31 of 54 cases (57%). If we consider SISCOM and (18)F-FDG PET results together, nuclear medicine imaging techniques showed coinciding video-EEG results in 76% of patients (41/54). In those cases in which MR imaging failed to identify any epileptogenic lesion (61% [33/54]), SISCOM or (18)F-FDG PET findings matched PEZ in 67% (22/33) of cases. CONCLUSION: SISCOM and (18)F-FDG PET provide complementary presurgical information that matched video-EEG results and clinical data in three fourths of our sample. SISCOM was particularly useful in those cases in which MR imaging findings were abnormal but no epileptogenic lesion was identified. Radionuclide imaging techniques are both useful and reliable, extending the possibility of surgical treatment to patients who may have been discouraged without a nuclear medicine approach.

Mirror-image lymph node in FDG PET/CT and SPECT/CT for sentinel node detection.

We report a case of a patient with presumed stage IB1 squamous cell carcinoma of the cervix in which FDG PET/CT scan revealed 1 hypermetabolic left iliac node suggestive to be malignant. Lymphoscintigraphy and SPECT/CT studies previous to sentinel node (SLN) biopsy revealed unilateral drainage in the right pelvis. Intraoperative pathological assessment of the SLN showed no tumoral involvement, and the hypermetabolic node revealed macrometastasis. Tumor node invasion can lead to a lymphatic blockage and become false-negative for SLN technique. Although FDG PET/CT has lower sensitivity than surgical staging, this case shows its value as a preoperative imaging technique.

Advantages of pinhole collimator double-phase scintigraphy with 99mTc-MIBI in secondary hyperparathyroidism.

PURPOSE: The aim of the study was to determine if pinhole collimator-acquired images can improve the detection of hyperfunctioning parathyroid glands in patients with secondary hyperparathyroidism. METHODS: Forty-two patients being treated with cinacalcet for secondary hyperparathyroidism were studied prospectively. Patients were divided into 2 groups according to their levels of parathyroid hormone (PTH), the hormone that defines response to treatment: "responders" (PTH <300 pg/mL) and "nonresponders" (PTH ≥ 300 pg/mL). Double-phase scintigraphy using 888 MBq of (99m)Tc-MIBI was used to acquire early and late parallel-hole and pinhole collimator images. Neck ultrasonography was performed on all patients to identify intrathyroid nodules. All focal uptake in any of the acquired scintigraphic images was considered positive. RESULTS: The responder group included 24 patients, whereas 18 patients were considered as nonresponders. At least 1 parathyroid gland with (99m)Tc-MIBI uptake was detected in 33 of 42 patients, with a total of 50 parathyroid glands located. We found significant differences between the detection rates of late pinhole collimator and the late parallel-hole images (74% vs 48%, P = 0.0036). This detection rate was highest with late parallel-hole images in the nonresponder group (89%). CONCLUSIONS: The late pinhole collimator acquisition showed the highest detection rate of hyperfunctioning parathyroid glands using (99m)Tc-MIBI scintigraphy in secondary hyperparathyroidism patients treated with cinacalcet.

Interim FDG PET/CT as a prognostic factor in diffuse large B-cell lymphoma.

PURPOSE: Interim (18)F-FDG PET performed early during the course of therapy in diffuse large B-cell lymphoma (DLBCL) is a good predictor of outcome. However, interpretation criteria for interim PET for the evaluation of tumour response are still not clearly defined. The study aim was to assess whether interim PET can predict overall survival (OS) and progression-free survival (PFS) in DLBCL patients following three different sets of parameters, two qualitative (visual) methods and one semiquantitative. METHODS: A total of 50 newly diagnosed DLBCL patients were prospectively enrolled in this study. All patients had a PET/CT scan at diagnosis and an interim PET/CT scan after the second or third cycle of chemotherapy. Three methods of evaluation for the interim PET/CT were used: a qualitative three-point scoring (3-PS) method, a qualitative 5-PS method and a semiquantitative method (ΔSUVmax). The degree of correlation between therapy response seen on FDG PET and PFS and OS was determined. RESULTS: The analysis of the visual 3-PS method showed no statistically significant difference in PFS and OS. The estimated 5-year PFS and OS were 79 % and 92 %, respectively, in patients with an interim PET scan showing uptake not greater than in the liver versus 50 % in patients with uptake greater than in the liver, and this difference was statistically significant. The optimal cut-off value of ΔSUVmax that could predict the PFS and OS difference in patients with DLBCL was 76 % (95 % CI 62.7-89.2 %) and 75 % (95 % CI, 54.6-95.4 %), respectively. CONCLUSION: Our results support the use of liver uptake as an indicator in the qualitative evaluation of interim PET, or a ΔSUVmax greater than 75 % in semiquantitative analysis. Interim PET may predict PFS and OS and could be considered in the prognostic evaluation of DLBCL.

A prospective study comparing whole-body FDG PET/CT to combined planar bone scan with 67Ga SPECT/CT in the Diagnosis of Spondylodiskitis.

PURPOSE: This study aimed to prospectively evaluate the usefulness of PET/CT using F-FDG in comparison to bone scan and Ga in the diagnosis of spondylodiskitis. MATERIAL AND METHODS: This prospective study included 34 patients (15 women and 19 men) aged 59 (18) years with clinical symptoms of spondylodiskitis. Whole-body PET/CT and bone scan combined with planar and SPECT/CT Ga was performed in all patients. Diagnosis of spondylodiskitis was made by microbiology and/or on the basis of clinical and laboratory findings and imaging follow-up. RESULTS: Spondylodiskitis was confirmed in 18 of 34 patients. In the other 16 patients, spondylodiskitis was finally excluded, and the most frequent findings observed were degenerative spondyloarthropathy (n = 7), vertebral fracture (n = 3), endocarditis (n = 2), and other processes (n = 4). The sensitivity and specificity of combined bone scan and Ga were 78% and 81%, with a positive predictive value of 82%, a negative predictive value of 76%, and an overall accuracy of 79%. SPECT/CT with Ga helped identify soft tissue involvement in 10 of 18 patients. The sensitivity and specificity of PET/CT were 89% and 88%, with a positive predictive value of 89%, a negative predictive value of 87%, and an overall accuracy of 88%. Concordance between Ga and PET/CT was good (κ = 0.71; 95% confidence interval, 0.48-0.94). PET/CT was able to detect soft tissue involvement in 12 of 18 patients. In 2 patients, a multifocality was found, which was only diagnosed by PET/CT. CONCLUSIONS: PET/CT is useful in the diagnosis of spondylodiskitis, with more accurate results than combined bone scan and Ga. SPECT/CT with Ga is recommended, especially when planar bone scan and Ga pattern is suggestive of spondylodiskitis.

Accuracy and reproducibility of lymphoscintigraphy for sentinel node detection in patients with cutaneous melanoma.

UNLABELLED: Lymphoscintigraphy is an important part of the mapping and identification of sentinel lymph nodes (SLNs). However, few studies report its reproducibility, and some concerns prevail. The aim of the study was to determine the reproducibility of lymphoscintigraphy performed by different team members following a strict protocol to assess lymphatic drainage and the location and number of SLNs. METHODS: Sixty-eight melanoma patients were included. All underwent 2 separate lymphoscintigraphy studies, which followed the same acquisition protocol. Discordance was defined as a change in localization or a failure to identify the SLN in one of the studies. RESULTS: All patients showed lymphatic drainage, and in all cases at least 1 sentinel node was identified. In 65 of 68 patients (96%), the findings of the first lymphoscintigraphy study were similar to those of the second. This similarity was also found in the number of sentinel nodes (171 in the first study and 173 in the second). Eighty percent of patients showed 1-3 SLNs in both lymphoscintigraphy studies. The 2 studies differed in 3 patients (4%): 2 melanomas were located on the trunk and 1 on the head and neck. Drainage was visualized to more than 1 lymphatic basin in 19 patients (28%) in the first study versus 18 patients in the second study. CONCLUSION: Lymphoscintigraphy is highly reproducible in the detection of sentinel nodes in melanoma patients. The classic protocol of radiotracer injection is reproducible and reliable enough to guarantee SLN identification, although a slight variation in isolated cases (especially when primary lesions are located on the trunk or the head and neck regions) is inevitable.

Validation of an automatic dose injection system for Ictal SPECT in epilepsy.

UNLABELLED: The purpose of our study was to evaluate the performance and clinical usefulness of an automated injector system (AIS) that administers an automated injection for ictal SPECT after calculating the volume of tracer to be injected over time. METHODS: To test the AIS, repeated injections were performed at different times after tracer preparation. The clinical study consisted of 56 patients with drug-resistant, complex partial seizures. Tracer for ictal SPECT was injected using automated injection in 27 patients and manual injection (MI) in the remaining 29. Injection time (T(I)) was measured in seconds from seizure onset to the end of volume injection. The SISCOM (Subtraction Ictal Spect Co-registered to MRI) procedure was used to locate the epileptogenic seizure focus with SPECT. The definition of seizure focus was made by consensus of the epilepsy unit using conventional diagnostic methods. RESULTS: During the experimental phase, there were no system failures, and the error in injected doses when using automated injection was lower than with MI. During the clinical phase, T(I) using manual injection was 41 s with a range of 14-103 s, compared with an AIS average of 33 s with a range of 19-63 s (P < 0.05). Ictal SPECT and SISCOM successfully localized the seizure focus in 21 of the 27 patients (78%) by AIS and in 19 of the 29 patients (65%) by MI (P = 0.14). Furthermore, nursing staff found the AIS method more convenient than the MI method. CONCLUSION: An AIS can improve the quality of work of the nursing staff in the neurology ward and allow a finer adjustment of the injection dose. Early results using an AIS would indicate a reduction in injection time and improved SPECT accuracy.

Validation of FDG-PET/MRI coregistration in nonlesional refractory childhood epilepsy.

PURPOSE: To validate the use of 18F-fluorodeoxyglucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) coregistration for epileptogenic zone detection in children with MRI nonlesional refractory epilepsy and to assess its ability to guide a second interpretation of the MRI studies. METHODS: Thirty-one children with refractory epilepsy whose MRI results were nonlesional were included prospectively. All patients underwent presurgical evaluation following the standard protocol of our epilepsy unit, which included FDG-PET and FDG-PET/MRI coregistration. Cerebral areas of decreased uptake in PET and PET/MRI fusion images were compared visually and then contrasted with presumed epileptogenic zone localization, which had been obtained from other clinical data. A second interpretation of MRI studies was carried out, focusing on the exact anatomic region in which hypometabolism was located in FDG-PET/MRI fusion images. KEY FINDINGS: Both FDG-PET and FDG-PET/MRI detected hypometabolism in 67.8% of patients, with good concordance on a subject basis and on the cerebral region involved (κ statistic = 0.83 and 0.79, respectively). Hypometabolism detected by single PET, as well as by PET/MRI fusion images, was located in the same hemisphere, as indicated by electroclinical data in 58% of patients, and at the same place in 39% of cases. Of the patients who showed hypometabolism on PET/MRI, 43% also experienced changes in the guided second MRI interpretation, from nonlesional to subtle-lesional. SIGNIFICANCE: PET/MRI coregistration is an imaging variant that is at least as accurate as PET alone in detecting epileptogenic zone in pediatric nonlesional patients, and can guide a second look at MRI studies previously reported as nonlesional, turning a meaningful percentage into subtle-lesional.

Assessment of radiofrequency ablation of lung metastasis from colorectal cancer using dual time-point PET/CT.

A 70-year-old man with operated colorectal cancer relapsed with a solitary lung metastasis. Dual time-point PET/CT performed at 60' (standard images) and after 2 hours (delayed images) showed focal uptake in the lung nodule. A second uptake in the liver dome was also visualized only in the delayed images. Radiofrequency of the lung metastasis was performed by CT-fluoroscopy guide. A PET/CT 1 month after radiofrequency showed significant reduction of activity in the delayed images, and the uptake at 3 months was virtually normal. A fine-needle biopsy of the liver lesion confirmed the final diagnosis of metastasis from adenocarcinoma.