fluoro-D-glucose Positron Emission Tomography Research Articles

The Effects of Aging on Testicular Volume and Glucose Metabolism: an Investigation with Ultrasonography and FDG-PET

To investigate the effects of senescence on testicular volume and metabolism by quantitative analysis of volumetric and functional data provided by genital ultrasonography (US) and 2-deoxy-2-[(18)F]fluoro-D-glucose(-)positron emission tomography (FDG-PET), respectively. Three hundred twenty (PET 173, US 147) male subjects (average age, 47.9 ± 24.1 years; range, 11-90 years) who previously underwent US or FDG-PET imaging were included in this retrospective study. Testicular volumes and FDG maximum standardized uptake values (SUV(max)) were correlated with age using polynomial regression and Pearson linear regression analysis. With cross-sectional analysis, the best-fit curves demonstrated statistically significant overall correlations between changes in both the volume and metabolism (SUV(max)) of the testicle and increasing age (volume: R(2) = 0.42, p = 0.0002; SUV(max): R(2) = 0.26, p < 0.0001). Testicular volume rapidly increases during puberty and peaks at age 30 years. Subsequently, the volume of the testes stabilizes in a plateau-like manner until age 60 years. After age 60 years, this study shows that testicular volume decreases significantly. Testicular glucose metabolism increases until age 40 years, after which it declines gradually over time at a constant rate. Testicular volume and metabolism appear to be significantly affected by advancing age at different rates during the different stages of lifespan. The rapid increase in testicular volume and metabolism parallel the onset and progression of puberty and positively correlate with increasing age up to ages 30-40 years. Between ages 40 and 60 years, testicular volume and metabolism remain relatively constant with only a minimal decline. After age of 60 years, the testicular volume significantly declines, while testicular metabolism progressively declines until age 90 years.

FDG-PET/CT in Cancers of the Head and Neck: What is the Definition of Whole Body Scanning?

The role of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) was studied in a variety of cancers, including head and neck squamous cell carcinomas (HNSCC) and nasopharyngeal carcinomas (NPC), with several presentations indicating that for these clinical entities a "whole-body" (i.e., eyes to thighs) may yield little additional information. Therefore, we were prompted to review our experience with PET/computed tomography (CT) in the management of patients with HNSCC and NPC. This is a retrospective study of 133 patients with HNSCC, 23-90years old (average: 58.2 ± 12.7) and 26 patients with NPC, ages 16-75 (average: 47.3 ± 17.1), who had whole body PET/CT at our institution from Jan 2003 to Nov 2006. Reinterpretation of the imaging studies for accuracy and data analysis from medical records was performed. Lesions identified on PET/CT below the level of the adrenal glands were recorded and tabulated. Lesions were identified below the adrenal glands in seven patients (5.2%) with HNSCC. These included hepatic and osseous metastases from HNSCC in two patients (1.5%), a new renal cancer (0.75%), a new pancreatic cancer (0.75%), a new colon cancer (0.75%) and findings proven benign on follow-up (focal colon uptake in one patient and an inflammatory inguinal lymph node in another patient; 1.5%). Lesions were identified below the adrenal glands in three patients (11.5%) with NPC. These included osseous metastases from NPC in two patients (7.7%) and findings proven benign on follow-up (focal colon uptake in one patient; 3.84%). This study suggests that whole body PET/CT imaging in HNSCC has a relatively low yield (3%, 95% CI: 1.33-8.42) of significant findings below the level of the adrenal glands. Therefore, implementing a more limited protocol (through the level of adrenal glands), especially in low-risk cases of HNSCC, may be considered. However, whole body PET/CT imaging in NPC may have a significant yield (7.7%, 95% CI: 1.02-25.26) of medically relevant findings below the level of the adrenal glands. Thus, the whole body (i.e., vertex to thighs) PET/CT scan of NPC patients appears to be the appropriate imaging protocol for this population. This recommendation requires further evaluation and validation in larger prospective studies.

Association of the VEGF 936C&gt;T Polymorphism with FDG Uptake, Clinical, Histopathological, and Metabolic Response in Patients with Adenocarcinomas of the Esophagogastric Junction

The MUNICON trial confirmed prospectively the usefulness of early response evaluation by 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) . Metabolic responders (R) showed initially a higher FDG uptake compared with nonresponders (p = 0.018). An association of the vascular endothelial growth factor (VEGF) 936C>T polymorphism and FDG uptake was reported for breast cancer. Therefore, we investigated the VEGF 936C>T polymorphism for an association with response and survival. The study was based on 110 patients included in the MUNCON trial (103 male, seven female; 75 AEG I, 35 AEG II, event-free survival (EFS) median 21.1 ± 4.6 months). Response was significantly associated with EFS. The VEGF 936C>T polymorphism was determined by PCR and restriction fragment length polymorphism analysis. For analysis, the T-variants were combined. One hundred two patients were evaluable. Seventy-two patients showed the CC, 24 the CT, and six the TT genotype. Median EFS was 29.3 months for CC and 11.7 months for CT/TT (p = 0.04). No association of the genotypes (CC or CT/TT) with the SUV or response was found. Multivariate analysis revealed histopathological regression (p = 0.003) and genotype (p = 0.04) as independent prognostic factors. A combination of genotype and PET response (Gen-PET) defines three prognostic groups early in the course of treatment (p = 0.002). Cox regression analysis including clinical and histopathological response and Gen-PET reveals Gen-PET as independent prognostic factor (p = 0.003). The VEGF 936C>T polymorphism is a prognostic factor in patients undergoing neoadjuvant chemotherapy, although it is not associated with FDG uptake and response. The combination of metabolic response and VEGF 936C>T polymorphism defines three different prognostic groups. These findings need to be confirmed prospectively. This study has been registered in the European Clinical Trials Database as trial 2007-003356-11.

Role of 2-deoxy-2-[F-18] fluoro-D-glucose positron emission tomography in the management of bone and soft-tissue metastases

We retrospectively reviewed 71 histopathologically-confirmed bone and soft-tissue metastases of unknown origin at presentation. In order to identify the site of the primary tumour all 71 cases were examined with conventional procedures, including CT, serum tumour markers, a plain radiograph, ultrasound examination and endoscopic examinations, and 24 of the 71 cases underwent 2-deoxy-2-[F-18] fluoro-D-glucose positron emission tomography (FDG-PET). This detected multiple bone metastases in nine patients and the primary site in 12 of the 24 cases; conventional studies revealed 16 primary tumours. There was no significant difference in sensitivity between FDG-PET and conventional studies. The mean maximal standardised uptake value of the metastatic tumours was significantly higher than that of the primary tumours, which is likely to explain why FDG-PET did not provide better results. It was not superior to conventional procedures in the search for the primary site of bone and soft-tissue metastases; however, it seemed to be useful in the staging of malignancy.

Evaluation of an Experimental Breath-holding Image Acquisition with Regard to Pulmonary Nodule Detection on Chest FDG PET Image

Breath-hold imaging has been performing more frequently to reduce the respiratory motion artifact in chest imaging by means of positron emission tomography (PET) using 2-deoxy-2-[18F]-fluoro-D-glucose(FDG). It is difficult to hold breath for 30 seconds or more. We evaluated an experimental breath-holding image acquisition using phantoms with regard to pulmonary nodule detection on chest FDG PET image to examine whether the total acquisition time could be reduced. Images obtained during 180 seconds of continuous movement were compared with static images recorded during 60 - 180 seconds (15 seconds×4, 6, 8, 10, 12 times). Although shorter acquisition times resulted in greater variability in background activity, images recorded under static conditions for 90 seconds (15 seconds×6 times) or less showed nodules that were smaller than those observable in images recorded during continuous movement for 180 seconds. Breath-holding therefore permits the detection of smaller nodules on chest FDG PET images at shorter acquisition times.

Performance of Integrated FDG-PET/Contrast-enhanced CT in the Diagnosis of Recurrent Pancreatic Cancer: Comparison with Integrated FDG-PET/Non-contrast-enhanced CT and Enhanced CT

The purpose of this study is to evaluate the accuracy of 2-deoxy-2-[F-18]fluoro-D: -glucose-positron emission tomography (FDG-PET)/computed tomography (CT) with intravenous contrast for depiction of recurrent pancreatic cancer, compared with PET/non-enhanced CT and CT. Forty-five patients previously treated for pancreatic cancer underwent PET/CT for suspected recurrence. Lesion status was determined on the basis of histopathology and radiological imaging follow-up. Patient-based analysis showed that sensitivity, specificity, and accuracy of PET/contrast-enhanced CT were 91.7%, 95.2%, and 93.3%, respectively, whereas those of PET/non-enhanced CT were 83.3%, 90.5%, and 86.7%, respectively, and those of enhanced CT were 66.7%, 85.7%, and 75.6%, respectively. In 21 patients whom the final diagnosis was obtained from the histopathologic examination, those figures of PET/contrast-enhanced CT were 94.7%, 50.0%, and 90.4%, respectively. The sensitivity of PET/contrast-enhanced CT in detecting local recurrence, abdominal lymph node metastasis, and peritoneal dissemination were 83.3%, 87.5%, and 83.3%, respectively. PET/contrast-enhanced CT is an accurate modality for assessing recurrence of pancreatic cancer.

Imaging Uterine Cervical Cancer with FDG-PET/CT: Direct Comparison with PET

To compare 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) and PET/computed tomography (CT) for certainty of image interpretation and for diagnostic accuracy in patients with primary and metastatic uterine cervical cancer. Images of 13 patients with cervical cancer having PET/CT examinations were reviewed retrospectively. PET and PET/CT images of all cases were read blindly and randomly by two readers. Foci of increased FDG uptake on PET or PET/CT were classified using a scoring system regarding lesion localization and characterization. PET and PET/CT findings were assessed with all clinical information available, and diagnostic accuracy was determined on a per-lesion and on a per-patient basis. For both readers, PET/CT provided significantly higher frequencies of definite lesion localization (>30% higher) and definite lesion characterization (>20% higher) compared to the findings on PET alone. The improvement in lesion localization to the definite level by PET/CT provided the definite lesion characterization in at least 50% of cases. PET/CT tended to exhibit higher diagnostic accuracy than PET alone on a lesion-based analysis (92% vs. 78% in reader 1 and 92% vs. 82% in reader 2, respectively). Metastatic disease spread was, however, almost equally evaluated between PET and PET/CT. PET/CT was demonstrated to be useful in the definite localization and characterization of foci of increased FDG uptake, which provided its higher diagnostic accuracy than PET alone. PET/CT appears preferable to PET in the evaluation of cervical cancer, although additional study is needed.

PET/CT in the Evaluation of Inflammatory Bowel Disease: Studies in Patients Before and After Treatment

The purpose of this study was to evaluate the appropriate 2-deoxy-2-[(18)F]fluoro-D-glucose-positron emission tomography (FDG-PET) determination in patients with inflammatory bowel disease (IBD) before and after clinical improvement to see if this determination correlates with clinical activity. We performed PET-computed tomography (PET/CT) on five patients before and after successful medical therapy in patients with moderately active IBD. Each patient had five bowel segments scored (0-3) for the appropriate FDG-PET determination. There were five patients [Crohn's disease (CD) = 3, ulcerative colitis = 2] who were studied an average of 437 days (range, 77-807) after initial PET/CT scan. All patients showed significant improvement in physician global assessment scores (p = 0.004) and underwent repeat PET/CT. The total score of all segments was 32 pretreatment and 14 posttreatment (p < 0.01). Of 11 pretreatment active segments, nine (82%) segments either became inactive or displayed decreased activity, while two showed no change (p < 0.001). Appropriate FDG-PET determination decreases with successful treatment of inflammation in active IBD and correlates with symptom improvement.

Impact of FDG-PET on Prediction of Clinical Outcome after Concurrent Chemoradiotherapy in Hypopharyngeal Carcinoma

To evaluate prognostic value of pretreatment and posttreatment 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) in advanced hypopharyngeal carcinoma treated by chemoradiotherapy. Thirty-one patients underwent a baseline FDG-PET and then FDG-PET was repeated 7 weeks after chemoradiotherapy. Primary tumor uptake of FDG, measured as the maximal standardized uptake value (SUV(max)), was analyzed in relation to local control and survival. Neither local control nor cause-specific survival were associated with pretreatment SUV(max). In contrast, patients with a high posttreatment SUV(max) had significantly poorer local control (P = 0.002), as well as poorer cause-specific survival (P = 0.0075), compared to those with a low posttreatment SUV(max). This prognostic significance of posttreatment SUV(max) remained when only a subset of patients showing local complete response to chemoradiotherapy was analyzed. Posttreatment FDG uptake represents an independent prognostic factor for hypopharyngeal carcinoma treated by chemoradiotherapy. Patients with a high posttreatment FDG uptake may benefit from adjuvant chemotherapy.

Pituitary Adenomas Can Appear as Hypermetabolic Lesions in 18F‐FDG PET Imaging

The 2-deoxy-2-[(18) F] fluoro-D-glucose positron emission tomography (FDG-PET) scan is commonly used in detection and staging of many malignant neoplasms. However, several benign or non-neoplastic conditions avidly accumulate (18) F-FDG, causing ambiguity in interpretation of results. It is unknown whether pituitary adenomas uptake (18) F-FDG and appear positive in PET imaging. Here, we present 2 cases of benign pituitary adenoma with elevated metabolic activity in (18) F-FDG PET scan. Medical, neurologic, and psychiatric histories; physical examination findings; laboratory work up results; and pathologic and imaging studies were documented. The (18) F-FDG-PET images revealed foci of marked FDG uptake in pituitary adenomas of 2 patients. Pituitary micro- and macro-adenomas may present as hypermetabolic foci on (18) F-FDG PET scan.

Early 2′-Deoxy-2′-[18F]Fluoro-d-Glucose PET Metabolic Response after Corticosteroid Therapy to Differentiate Cancer from Sarcoidosis and Sarcoid-like Lesions

We aimed at investigating whether early metabolic response to corticosteroid therapy may be used as a diagnostic tool to discriminate between cancer and sarcoidosis, a well-known cause of false-positive 2-deoxy-2-[F-18]fluoro-D: -glucose-positron emission tomography (FDG-PET) findings in oncology. Two cancer patients with biopsy-proven sarcoidosis or sarcoid-like reaction had multiple thoracic FDG foci. After infectious disease had been excluded, patients received oral corticosteroids for 16 and 14 days, respectively, and underwent posttherapeutic FDG-PET examination. Posttreatment PET revealed a complete metabolic response in both patients, and clinical and imaging follow-up showed no sign of cancer progression. Early metabolic response to systemic corticosteroid treatment may be used as a tool in the establishment of final diagnosis when sarcoidosis is suspected in a cancer patient and could be capable of differentiating cancer from sarcoidosis in the case of coexisting diseases.

An In Vivo Multimodal Imaging Study Using MRI and PET of Stem Cell Transplantation after Myocardial Infarction in Rats

The purpose of the study is to track iron-oxide nanoparticle-labelled adult rat bone marrow-derived stem cells (IO-rBMSCs) by magnetic resonance imaging (MRI) and determine their effect in host cardiac tissue using 2-deoxy-2-[F-18]fluoro-D: -glucose-positron emission tomography (FDG-PET). Infarcted rats were randomised to receive (1) live IO-rBMSCs by direct local injection, or (2) dead IO-rBMSCs as controls; (3) sham-operated rats received live IO-rBMSCs. The rats were then imaged from 2 days to 6 weeks post-cell implantation using both MRI at 9.4T and FDG-PET. Implanted IO-rBMSCs were visible in the heart by MRI for the duration of the study. Histological analysis confirmed that the implanted IO-rBMSCs were present for up to 6 weeks post-implantation. At 1 week post-IO-rBMSC transplantation, PET studies demonstrated an increase in FDG uptake in infarcted regions implanted with live IO-rBMSC compared to controls. Noninvasive multimodality imaging allowed us to visualise IO-rBMSCs and establish their affect on cardiac function in a rat model of myocardial infarction (MI).

Dose-Dependent Effects of Radiation Therapy on Cerebral Blood Flow, Metabolism, and Neurocognitive Dysfunction

A prospective study was performed to formally relate dose-dependent radiologically defined changes in normal brain induced by radiotherapy (RT) to neurocognitive dysfunction in subjects with primary brain tumors. Adult patients receiving three-dimensional RT for central nervous system (CNS) tumors were enrolled. Positron emission tomography (PET) scanning and neuropsychological testing were performed before RT and 3 weeks and 6 months after treatment. Analyses were performed for correlations between changes in 2-deoxy-2-[(18)F]-fluoro-d-glucose (FDG)-PET (metabolism), (15)O-PET (relative blood flow), regional radiation dose, follow-up time, and neuropsychological test scores. Eleven subjects were enrolled and 6 completed follow-up studies. The PET data showed reduced FDG uptake, with average decreases of 2-6% in regions of the brain receiving greater than 40 Gy at 3 weeks' and 6 months' follow-up. The (15)O-H(2)O PET showed increases (<10%) at 3 weeks in relative regional blood flow in brain receiving greater than 30 Gy, but less at the 6-month follow-up studies. There were significant correlations between decreases in FDG uptake and increased scores from the Symptom Checklist-90-R, with an average increase in T score of 2 (p < 0.0001). The Wisconsin Card Sorting Test showed a significant correlation of decreased FDG uptake with increased errors and perseveration in test performance, with an average decrease in T score of 11 (p = 0.037). A dose-dependent response of CNS tissue was detected using FDG PET in this small number of patients. Decreases in CNS metabolism correlated with decreased performance on neuropsychological tests for problem solving, cognitive flexibility, and global measures of psychopathology. Additional research is needed to verify and define these findings.

Prospective Comparison of FDG and FET PET/CT in Patients with Head and Neck Squamous Cell Carcinoma

The clinical usefulness of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) in head and neck squamous cell carcinoma (HNSCC) is now well-documented. However, its sensitivity is greater than its specificity due to false-positive results in inflammatory or infectious lesions, which are frequent in this area, in particular after treatment by surgery and/or radiotherapy. O-2-fluoro-(18F)-ethyl-L-thyrosine (FET) has been reported not to be taken up by such lesions, and a preliminary study indicated that this may be clinically useful in HNSCC. We performed a prospective study to compare the diagnostic performances of FDG and FET PET/CT in the different settings of HNSCC. Twenty-seven patients (20 men and seven women, aged 48-76, among 30 patients included) and 69 suspected cancer sites are now evaluable on basis of postsurgical histology and/or follow-up greater than 6 months; 15 patients were referred for initial staging and 12 during posttherapy follow-up, a recurrence being suspected in eight of them. FDG and FET PET/CT were performed on two different days, the patient fasting for 6 h, 1 h after injection of 5 MBq/kg of body mass of each radiopharmaceutical. Both PET/CT examinations were blind read more than 6 months after the end of inclusions in a random order for each tracer and with a time interval greater than 1 month between FDG and FET PET/CT blind readings. Overall diagnostic performances, derived from blind reading: FDG PET/CT on a per patient basis: sensitivity 100%, specificity 71%, accuracy 93%; FDG PET/CT on a per site basis: sensitivity 95%, specificity 63%, accuracy 83%; FET PET/CT on a per patient basis: sensitivity 70%, specificity 100%, accuracy 78%; FET PET/CT on a per site basis: sensitivity 64%, specificity 100%, accuracy 78%. At site level, sensitivity was significantly greater with FDG (p<0.02) and specificity with FET (p<0.01). The statistical level of significance was not reached at patient level. Although its good specificity was confirmed, FET did not appear to be suited as a first-line PET tracer in HNSCC imaging and cannot replace FDG for staging due to insufficient sensitivity. However, it was useful in a few selected cases to favor a wait and see attitude when a FDG+ FET- focus was discovered in patients referred for systematic FDG PET during follow-up. In contrast, second primary cancers should not be ruled out if FDG was clearly positive in the lungs or the digestive tract.

2-Deoxy-2[F-18]FDG-PET for Detection of Recurrent Laryngeal Carcinoma after Radiotherapy: Interobserver Variability in Reporting

PurposeTo evaluate accuracy and interobserver variability in the assessment of 2-deoxy-2[F-18]fluoro-d-glucose-positron emission tomography (FDG-PET) for detection of recurrent laryngeal carcinoma after radiotherapy.ProceduresEleven experienced nuclear physicians from eight centres assessed 30 FDG-PET scans on the appearance of local recurrence (negative/equivocal/positive). Conservative (equivocal analysed as negative) and sensitive (equivocal analysed as positive) assessment strategies were compared to the reference standard (recurrence within 6months after PET).ResultsSeven patients had proven recurrences. For the conservative and sensitive strategy, the mean sensitivity was 87% and 97%, specificity 81% and 63%, positive predictive values 61% and 46% and negative predictive values 96% and 99%, respectively. Interobserver variability showed a reasonable relation in comparison to the reference standard (kappa = 0.55).ConclusionsFDG-PET has acceptable interobserver agreement and yields good negative predictive value for detection of recurrent laryngeal carcinoma. It could therefore be used as first diagnostic step and may reduce futile invasive diagnostics.

Prognostic Value of FDG-PET in Patients with Oropharyngeal Carcinoma Treated with Concurrent Chemoradiotherapy

PurposeThe purpose of this study was to evaluate the predictive value of 2-deoxy-2-[F-18]fluoro-d-glucose-positron emission tomography (FDG-PET) following concurrent chemoradiotherapy (CRT) on survival in patients with carcinoma of the oropharynx (OPC).MethodsEighteen patients with primary OPC who underwent PET pre- and post-CRT were evaluated prospectively for survival. The prognostic performance of post-CRT PET and CT for recurrence was compared.ResultsPatients with positive post-CRT PET exhibited significantly lower 2-year cause-specific survival and disease-free survival (50% vs. 91%, P < 0.05 and 0% vs. 83%, P < 0.0001); however, patients with positive post-CRT CT did not exhibit any significant difference (67% vs. 83%, P = 0.416 and 50% vs. 75%, P = 0.070). Other factors, such as clinical and pre-CRT PET variables, also did not indicate any significant difference. The accuracy of prediction of residual and local recurrence for post-CRT PET and CT (local%/regional%) was 83%/94% and 83%/78%, respectively.ConclusionOPC patients with positive post-CRT PET exhibit poor survival. The prognostic accuracy of post-CRT PET is superior to that of CT. The results of post-CRT FDG-PET should be included in the management of the OPC patients.

The Effects of Anesthetic Agent and Carrier Gas on Blood Glucose and Tissue Uptake in Mice Undergoing Dynamic FDG-PET Imaging: Sevoflurane and Isoflurane Compared in Air and in Oxygen

We sought to identify an anesthetic regime that, unlike isoflurane in air, would maintain glucose homeostasis in mice undergoing Positron emission tomography (PET) imaging with 2-deoxy-2-[18F]fluoro-D: -glucose (FDG). FDG uptake was also measured in normal and tumor tissues. Athymic and Balb/c nude mice were studied. Blood glucose levels were measured before and after 30 min of FDG PET imaging under isoflurane or sevoflurane carried in air or oxygen. FDG uptake was quantified as a percentage of the injected dose and using Patlak analysis yielding Ki values. Blood glucose levels were more stable under sevoflurane than under isoflurane, especially in the athymic nude mice. Under isoflurane, FDG uptake into myocardium was higher than under sevoflurane and was strongly correlated with the intrascan change in blood glucose. Sevoflurane should be preferred for physiologic imaging in mice, minimizing changes in glucose and, for FDG PET, reducing signal spillover from the myocardium.

Abnormal cerebral glucose metabolism in alternating hemiplegia of childhood

Alternating hemiplegia of childhood (AHC) is a rare and intractable disorder of unknown cause. To determine cerebral neuronal function in five patients with AHC (two adults and three children), we analyzed brain glucose metabolism by positron emission tomography (PET) using 2-deoxy-2 [ 18F] fluoro- d-glucose (FDG), performed between hemiplegic attacks. Interictal FDG–PET revealed abnormal cerebral glucose metabolism; all patients showed low glucose metabolism in the frontal lobes with some laterality, and three had low glucose metabolism in the ipsilateral putamen. The adult patients also showed low glucose metabolism and mild atrophy in the cerebellum. Glucose metabolism in the brainstem was virtually normal for all patients. The areas of low glucose metabolism indicated local or regional neuronal damage, possible reflecting progressive neurological symptoms. AHC might therefore result from focal abnormal glucose metabolism in the brain occurring progressively or permanently, particularly in the frontal lobes and the cerebellum.

Mucosa-associated lymphoid tissue lymphoma studied with FDG-PET: a comparison with CT and endoscopic findings

We investigated the accumulation of 2-deoxy-2-[(18)F] fluoro-D: -glucose positron emission tomography (FDG-PET) in patients with mucosa-associated lymphoid tissue (MALT) lymphoma patients as compared with computerized tomography (CT) and endoscopic imaging. FDG-PET was performed on 13 untreated patients with MALT lymphoma. CT scanning of the affected areas was performed in all the patients to compare with the FDG-PET images. In five patients with gastric MALT lymphoma, comparison was also made with the endoscopic findings. Of the 13 untreated MALT lymphoma patients, all 8 non-gastric MALT lymphoma patients exhibited abnormal accumulation of FDG. However, in the five gastric MALT lymphoma patients, no abnormal FDG accumulation was observed. Although lesions could be confirmed on CT images from the patients other than those with gastric MALT lymphoma, the mucosal lesions of gastric MALT lymphoma could be observed only by endoscopy. FDG-PET can be used to detect MALT lymphoma when it forms mass lesions, whereas it is difficult to detect non-massive MALT lymphoma of gastrointestinal origin.

Assessment of Cerebral Glucose Metabolism in Cat Deafness Model: Strategies for Improving the Voxel-Based Statistical Analysis for Animal PET Studies

The aim of this study was to establish the procedures for 3D voxel-based statistical analysis of 2-deoxy-2-[(18)F]fluoro-D-glucose-positron emission tomography (FDG-PET) images of a cat's brain obtained using a small animal-dedicated PET system and to assess the utility of this approach in investigating the cerebral glucose metabolism in an animal model of cortical deafness. This study compared several different strategies for the spatial processing of PET data acquired twice from eight cats before and after inducing deafness in terms of the comparability of the statistical analysis results to the established pattern of the cerebral glucose metabolic changes in the deaf animals. The accuracy of the spatial preprocessing procedures and the statistical significance of the comparison were improved by removing the background activities outside the brain regions. The use of the spatial normalization parameters obtained from the mean image of the realigned data set for individual data also helped improve the statistical significance of the paired t testing. It was also found that an adjustment of the registration options was also important for increasing the precision of the realignment. A method for voxel-based analysis of the PET data of a cat's brain was optimized. The results demonstrated the high localization accuracy and specificity of this method, which is expected to be useful for examining the brain PET data of medium-sized animals such as cats.