F-18 Fluorodeoxyglucose Positron Emission Tomography Scans Research Articles

Pleural Uptake Patterns in F18Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) Scans Improve the Identification of Malignant Pleural Effusions.

The confirmation of malignant pleural effusions (MPE) requires an invasive procedure. Diagnosis can be difficult and may require repeated thoracentesis or biopsies. F18Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) can characterize the extent of malignant involvement in areas of increased uptake. Patterns of uptake in the pleura may be sufficient to obviate the need for further invasive procedures. This is a retrospective review of patients with confirmed malignancy and suspected MPE. Patients who underwent diagnostic thoracentesis with cytology and contemporaneous FDG-PET were identified for analysis. Some underwent confirmatory pleural biopsy. The uptake pattern on FDG-PET underwent blinded review and was categorized based on the pattern of uptake. One hundred consecutive patients with confirmed malignancy, suspected MPE and corresponding FDG-PET scans were reviewed. MPE was confirmed in 70 patients with positive pleural fluid cytology or tissue pathology. Of the remaining patients, 15 had negative cytopathology, 14 had atypical cells and 1 had reactive cells. Positive uptake on FDG-PET was noted in 76 patients. The concordance of malignant histology and positive FDG-PET occurred in 58 of 76 patients (76%). Combining histologically confirmed MPE with atypical cytology, positive pleural FDG-PET uptake had a positive predictive value of 91% for MPE. An encasement pattern had a 100% PPV for malignancy. Positive FDG-PET pleural uptake represents an excellent method to identify MPE, especially in patients with an encasement pattern. This may eliminate the need for additional invasive procedures in some patients, even when initial pleural cytology is negative.

A 3D deep convolutional neural network approach for the automated measurement of cerebellum tracer uptake in FDG PET-CT scans.

The purpose of this work was to assess the potential of deep convolutional neural networks in automated measurement of cerebellum tracer uptake in F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scans. Three different three-dimensional (3D) convolutional neural network architectures (U-Net, V-Net, and modified U-Net) were implemented and compared regarding their performance in 3D cerebellum segmentation in FDG PET scans. For network training and testing, 134 PET scans with corresponding manual volumetric segmentations were utilized. For segmentation performance assessment, a fivefold cross-validation was used, and the Dice coefficient as well as signed and unsigned distance errors were calculated. In addition, standardized uptake value (SUV) uptake measurement performance was assessed by means of a statistical comparison to an independent reference standard. Furthermore, a comparison to a previously reported active-shape-model-based approach was performed. Out of the three convolutional neural networks investigated, the modified U-Net showed significantly better segmentation performance. It achieved a Dice coefficient of 0.911±0.026, a signed distance error of 0.220±0.103mm, and an unsigned distance error of 1.048±0.340mm. When compared to the independent reference standard, SUV uptake measurements produced with the modified U-Net showed no significant error in slope and intercept. The estimated reduction in total SUV measurement error was 95.1%. The presented work demonstrates the potential of deep convolutional neural networks in automated SUV measurement of reference regions. While it focuses on the cerebellum, utilized methods can be generalized to other reference regions like the liver or aortic arch. Future work will focus on combining lesion and reference region analysis into one approach.

Early metabolic change in (18)F-FDG-PET by measuring the single largest lesion predicts chemotherapeutic effects and patients' survival: PEACH study.

The objective of this study was to investigate the predictive value of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) for early assessment of tumor response to chemotherapy and for patient survival in gynecologic malignancies. We performed CT and FDG-PET scans before initiation of chemotherapy to determine baseline conditions. PET scan was repeated after the first cycle of chemotherapy. The tumor response was later evaluated by CT scans after three cycles of chemotherapy, using RECIST. The PET response was analyzed in terms of the difference in SUVmax for FDG of the patient's largest lesion between the baseline scan and after the first cycle of chemotherapy. The metabolic response for the tumor was defined as a 30% reduction in its SUVmax. Eleven patients received platinum-based regimens, and 20 patients received non-platinum-based regimens. The mean progression-free survival (PFS) for the patients with a metabolic response was 13 months (range 5-29). In contrast, the mean PFS of the patients with no metabolic response was only 4.3 months (range 1-18). There was a statistically significant difference between the metabolic response and PFS (p = 0.002, Mann-Whitney U test). There was a strong correlation between the metabolic response and RECIST, regardless of the chemotherapy regimens used (platinum-based group, p = 0.006; non-platinum group, p = 0.046, Fisher's exact test). The metabolic change in SUVmax was clearly predictive of tumor response in 93.5% of patients. Early FDG-PET assessment by measuring the single largest lesion is a very promising tool for rapidly predicting tumor responses and patient survival, regardless of the chemotherapy regimen.

Adrenocortical Carcinoma: False Positive in an I-123 Metaiodobenzylguanedine Scan.

A 55-year-old man with a personal history of left pheochromocytoma 2 years previously presented with an abdominal mass. Tumor relapse was suspected.Abdominal ultrasound showed a large left upper quadrant solid mass (calipers), with heterogeneous echogenicity and central cystic degeneration areas or necrosis (Fig. 1a). A computed tomography (CT) scan showed surgical clips of left adrenalectomy and multiple confluent left upper quadrant masses with a maximal diameter of 19 cm and heterogeneous enhancement (Fig. 1b). Both CT scan and ultrasound images were suspicious of adrenocortical carcinoma (ACC): size, heterogeneity and diaphragm invasion among other radiological features. Clinically, the mass grew in a few months and there were no paroxysmal hypertension episodes, nor elevation of catecholamines (cathecholamine urine test: 37.2 μg/g creatinine, normal range 0.1-260). F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed as ACC was suspected (2). ACC is an uncommon malignant neoplasm of unknown cause; however, smoking and oral contraceptives may be risk factors [1, 2]. Patients usually present with advanced-stage disease and have poor prognosis [3], with a 2-year recurrence rate that ranges from 73 to 86 % [4]. CT or magnetic resonance (MR) is most often used for initial staging of ACC and usually shows heterogeneous adrenal mass with variable enhancement of solid components [4]. F-18 FDG PET has been used successfully for detection of adrenal metastases and for staging ACC [5]. Most ACCs accumulate and retain FDG [2, 6]. However, FDG PET cannot differentiate among malignant lesions (metastases, ACC, malignant pheochromocytoma, and lymphoma). Also, most pheochromocytomas (benign or malignant) are metabolically active and might accumulate FDG [7, 8]. A whole-body FDG PET scan (coronal and axial view) shows increased irregular FDG uptake in the abdominal masses (Fig. 2). An I-123 metaiodobenzylguanedine (MIBG) scan was requested to rule out pheochromocytoma because, although conventional image methods (ultrasound and CT) and also PET/CT scan were suspicious of ACC, the primary histology of the tumor was consistent with pheochromocytoma. An MIBG scan was performed after injection of 185 MBq of I123 MIBG intravenously. Single photon emission tomography (SPECT)/CT scan showed abnormal isotope accumulation in the tumor region. The patient underwent total resection of the tumor. The histology was of ACC, with areas of necrosis and cystic areas, so the result of the MIBG scan was a false positive. No positive chromaffin staining or chromogranin ISSN (print) 1869-3474 ISSN (online) 1869-3482

Detection of Inflammatory Lesions by F-18 Fluorodeoxyglucose Positron Emission Tomography in Patients with Polymyositis and Dermatomyositis

To evaluate the usefulness of F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging in the management of patients with inflammatory myopathy. We examined whether FDG-PET scanning detects myositis or extramuscular lesions in patients with polymyositis (PM) and dermatomyositis (DM). FDG-PET imaging was performed in 24 patients with active inflammatory myopathy (PM, 11; DM, 13). The images were read by radiologists in a blinded manner. FDG uptake into muscles was judged positive when the intensity of muscles was higher than or equal to that of the liver. As controls, FDG imaging findings of patients with a lung mass and without muscle diseases were used. To investigate associations between FDG-PET findings and clinical/laboratory findings, the patients' medical records were reviewed retrospectively. Increased FDG uptake in muscles was found in 8 of 24 (33%) patients. In 67 of 69 (97%) controls without muscle diseases, no muscle FDG uptake was detected. The sensitivity of FDG-PET to detect myositis was lower than that of electromyogram (EMG), magnetic resonance imaging, and muscle biopsy. There were no significant differences in clinical manifestations between patients with and without increased FDG uptake in muscles, although patients with FDG muscle uptake had a tendency to have extended myositis with endomysial cell infiltration. FDG-PET detected neoplasms in patients with associated malignancy. FDG uptake in lungs was found in 7 of 18 patients with interstitial lung disease. FDG-PET imaging has limited usefulness for the evaluation of myositis in patients with PM/DM because of its low sensitivity, although it might be useful for detection of malignancy in these patients.

F 18 fluorodeoxyglucose positron emission tomography "super scan" in a patient of metastatic primitive neuroectodermal tumor of the kidney

We report F-18 fluorodeoxyglucose (FDG) “positron emission tomography (PET) super scan” akin to “super scan” of conventional skeletal scintigraphy, in a rare case of primitive neuroectodermal tumor (PNET) of the kidney. A twelve year old male patient of metastatic PNET of the kidney was subjected to a “true” whole body F-18 FDG PET scan including lower limbs and skull region as per the institution protocol. The images revealed extensive hypermetabolic areas corresponding to the computed tomography described renal, hepatic, and pancreatic lesions along with intense and non-uniform uptake in the marrows of axial and appendicular skeletal system. Interestingly, low background tracer concentration was observed along with very low F-18 FDG uptake in the brain, skeletal muscles of limb, mediastinum, and bowel. In view of these findings, the scan can be interpreted as “PET super scan” due to its resemblance with the super scan of skeletal scintigraphy. A repeat F-18 FDG PET scan after chemotherapy revealed marked treatment response with disappearance of “super scan”-like pattern, reduction in number, size, metabolic activity of the lesions, and stimulated marrow sans the previously diseased portion. Though uncommon, the reporting physician should be aware of “PET super scan” and its implications as described in this case.

The Role of Integrated F-18-FDG-PET Scanning in the Detection of M1 Disease in Oesophageal Adenocarcinoma and Impact on Clinical Management

IntroductionThe aim of this study was to evaluate the efficacy of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) scanning in the staging of oesophageal adenocarcinoma. MethodsOne hundred four patients with biopsy-proven adenocarcinoma underwent 18F-FDG-PET scan. FDG avid lesions were further investigated to their diagnostic conclusion. ResultsNineteen patients (18.26%) were found to have non-loco-regional FDG uptake. Of the patients, 3.84% were found to have M1 disease and 7.69% were found to have a second primary tumour. The sensitivity and specificity of FDG-PET scanning to detect metastatic disease in our series was 57.14% and 84.53%, respectively. The overall diagnostic accuracy was 82.69%. ConclusionsPET scanning improves staging and prevents unnecessary surgery in patients with M1 disease. It represents a good adjunct to computed tomography scanning and endoscopic ultrasound in the staging of oesophageal adenocarcinoma. The detection of asymptomatic coexisting synchronous cancers is an added benefit provided by PET scanning over similar diagnostic modalities.

The Prognostic Value of the Metabolic Tumor Volume in FIGO stage IA to IIB Cervical Cancer for Tumor Recurrence: Measured by F-18 FDG PET/CT.

The purpose of this study was to evaluate the prognostic value of the metabolic tumor volume (MTV), in FIGO stage IA-IIB cervical cancer patients, measured by F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging. Forty-five patients with invasive cervical cancer who underwent FDG-PET imaging were recruited. Metabolically active tumor regions were delineated on the pretreatment FDG-PET scans by encompassing regions equal to or greater than an standardized uptake value (SUV) of 40% of the peak tumor intensity. The relationship of the metabolic tumor volume (MTV) to the disease-free survival was analyzed. The MTV of the cervical cancer was compared with pathological and clinical prognostic factors, including lymph node metastasis, parametrial invasion, the depth of invasion, resection margins, tumor differentiation and FIGO stages. Cox proportional hazard regression analysis showed that the MTV was a significant independent predictor of recurrence of cervical cancer (p = 0.027). Patients with an MTV of >20cm(3) had a significantly reduced disease-free survival compared with patients with an MTV ≤ 20cm(3) (p = 0.029). The correlation of the MTV with traditional prognostic factors showed significantly higher values in patients that were lymph node (LN) metastasis positive (p = 0.028) and parametrial invasion positive (p = 0.022). The MTV significantly differed among the groups according to tumor differentiation (p = 0.0319) and FIGO stage (p = 0.001). The MTV measured by FDG-PET was an independent prognostic factor for tumor recurrence in patients with stage IA-IIB cervical cancer. These findings must be confirmed by large population based prospective studies.

Accuracy of FDG-PET in the Detection of Colonic Neoplasms

PURPOSE: There is little published data on the sensitivity and specificity of F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in the detection of colon polyps and early colon cancer. We performed a prospective evaluation of the utility of FDG-PET for the detection of colonic lesions in patients referred for polypectomy or endoscopic mucosal resection. METHODS: 29 patients who were referred for polypectomy or endoscopic mucosal resection of colon polyps, flat lesions and early cancers underwent FDG-PET. A total of 10 cancers and 27 precancerous lesions (adenoma, carcinoma in situ) were present in these patients. Histological confirmation was available in all cases. In cases where complete removal could not be performed endoscopically, surgery was performed. FDG-PET scans were considered true positives when a hypermetabolic abnormality was detected in the region where a lesion was identified on colonoscopy and false positives when a lesion was detected in an inappropriate location based on the colonoscopy results. RESULTS: FDG-PET detected 100% (3/3) of cancers larger than 1.5 cm but only 29% (2/7) of cancers up to 1.5 cm in diameter. 3 of the 4 polypoid cancers were detected, while a 1 cm polypoid cancer was not. Among the flat cancers, which were all 1.5 cm or smaller, only 2/6 were detected. Of the precancerous lesions, FDG-PET detected 83% (5/6) of lesions 3 cm or larger, 50% (2/4) of lesions between 1.6 and 2.9 cm, and 18% (3/17) of lesions between 1 and 1.5 cm. Only 2/9 flat precancerous lesions were detected. There were no false positive readings. CONCLUSIONS: In this prospective study, FDG-PET was highly specific but had limited sensitivity for precancerous and cancerous lesions smaller than 1.5 cm in diameter. Most polypoid adenomas and all polypoid carcinomas larger than 1.5 cm were detected by FDG-PET, while most flat adenomas and flat carcinomas were missed.

F-18-fluoro-deoxy-glucose positron-emission tomography scanning in detection of local recurrence after radiotherapy for laryngeal/ pharyngeal cancer.

The objective of this investigation was to determine whether F18-fluoro-deoxy-glucose (FDG) positron-emission tomography (PET) could differentiate between local recurrence and late radiation effects after radiotherapy for laryngeal/pharyngeal cancer. In a prospective study of 75 patients (67 larynx, eight oro/hypopharynx), 160 laryngoscopies and 109 FDG PET scans were performed on the head and neck region. The mean follow-up time after the first FDG PET scan was 23 months (minimum 1 year). Local recurrence was diagnosed in 37 patients: 19 after the first biopsy and 18 after follow-up biopsies. For all of the negative initial FDG scans (27), the biopsies that were taken at the same time were negative and no recurrence was seen for at least 1 year. The first FDG scan was a true positive in 34 of 48 patients. In 12 of the 14 patients with false-positive results, FDG scans were repeated; a decreased FDG uptake was found in 9 of the 12. The sensitivity and specificity of the first scan were respectively 92% and 63%; including subsequent FDG scans, the rates were 97% and 82%, respectively. When a local recurrence is suspected after radiotherapy for cancer of the larynx/pharynx, an FDG PET scan should be the first diagnostic step. No biopsy is needed if the scan is negative. If the scan is positive and the biopsy negative, a decreased FDG uptake measured in a follow-up scan indicates that a local recurrence is unlikely.

Efficacy of F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) scans in diagnosis of pulmonary nodules

To evaluate the value of F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) scans, we performed FDG-PET scans in 23 patients with indeterminate pulmonary nodules less than 3 cm in size and analyzed these scans qualitatively and semiquantitatively. Histologic specimens were obtained by thoracoscopic excisional biopsy in 16 patients, CT-guided needle aspiration cytology in three, and bronchoscopic brushing cytology in four. Pathological diagnoses were lung cancer in 16 patients, benign inflammation in six, and malignant lymphoma in one. Sensitivity, specificity and accuracy of the FDG-PET scans were 88% (15/17), 67% (4/6) and 83% (19/23), respectively. There were two false-positive cases (organizing pneumonia and cryptococcosis) and two false-negative ones (slow-growing adenocarcinoma and malignant lymphoma). Although a few false-positive cases of granulomatous disease were yielded, the FDG-PET scans were highly sensitive in the detection of lung cancer. We conclude that the FDG-PET scanning in a useful diagnostic imaging modailty in the management of indeterminate pulmonary nodules.