Metabolic activity assessment by 18 F-fluorodeoxyglucose positron emission tomography in patients with hepatocellular carcinoma undergoing Yttrium-90 transarterial radioembolization.

BACKGROUND AND AIM: 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is a functional image technique that can inform clinical decisions related to prognosis. We investigated the predictive role of 18 F-fluorodeoxyglucose PET/CT in patients with hepatocellular carcinoma (HCC) undergoing Yttrium-90 (Y-90) transarterial radioembolization (TARE). METHODS: Patients with HCC treated with TARE and pre-TARE PET/CT scan were recruited between 2009 and 2013. Maximum standardized uptake value and tumor-to-non-tumorous liver uptake ratio (TLR) were measured. Tumor response was evaluated in accordance with modified RECIST criteria at 3-month intervals after Y-90 TARE. RESULTS: Forty patients were included in the final analysis. The median age was 56.5 years and male predominant. Disease control in treated lesion was achieved in 82.5% (n = 33) of patients. During median 18.3-month follow-up, 27.5% (n = 11) of patients achieved progression-free survival. The cutoff of TLR, which was related to the median value, did not affect disease control rate, progression-free survival, and overall survival in patients with Y-90 TARE. CONCLUSIONS: The TLR-based stratification may be a simple method, but our study did not show the usefulness in predicting prognosis in HCC patients with Y-90 TARE. Further studies with large number of patients are needed.

Three-Hour Delayed Imaging Improves Assessment of Coronary 18F-Sodium Fluoride PET.

Coronary 18F-sodium fluoride (18F-NaF) PET identifies ruptured plaques in patients with recent myocardial infarction and localizes to atherosclerotic lesions with active calcification. Most studies to date have performed the PET acquisition 1 h after injection. Although qualitative and semiquantitative analysis is feasible with 1-h images, residual blood-pool activity often makes it difficult to discriminate plaques with 18F-NaF uptake from noise. We aimed to assess whether delayed PET performed 3 h after injection improves image quality and uptake measurements. Methods: Twenty patients (67 ± 7 y old, 55% male) with stable coronary artery disease underwent coronary CT angiography (CTA) and PET/CT both 1 h and 3 h after the injection of 266.2 ± 13.3 MBq of 18F-NaF. We compared the visual pattern of coronary uptake, maximal background (blood pool) activity, noise, SUVmax, corrected SUVmax (cSUVmax), and target-to-background (TBR) ratio in lesions defined by CTA on 1-h versus 3-h 18F-NaF PET. Results: On 1-h PET, 26 CTA lesions with 18F-NaF PET uptake were identified in 12 (60%) patients. On 3-h PET, we detected 18F-NaF PET uptake in 7 lesions that were not identified on 1-h PET. The median cSUVmax and TBRs of these lesions were 0.48 (interquartile range [IQR], 0.44-0.51) and 1.45 (IQR, 1.39-1.52), respectively, compared with -0.01 (IQR, -0.03-0.001) and 0.95 (IQR, 0.90-0.98), respectively, on 1-h PET (both P < 0.001). Across the entire cohort, 3-h PET SUVmax was similar to 1-h PET measurements (1.63 [IQR, 1.37-1.98] vs. 1.55 [IQR, 1.43-1.89], P = 0.30), and the background activity was lower (0.71 [IQR, 0.65-0.81] vs. 1.24 [IQR, 1.05-1.31], P < 0.001). On 3-h PET, TBR, cSUVmax, and noise were significantly higher (respectively: 2.30 [IQR, 1.70-2.68] vs. 1.28 [IQR, 0.98-1.56], P < 0.001; 0.38 [IQR, 0.27-0.70] vs. 0.90 [IQR, 0.64-1.17], P < 0.001; and 0.10 [IQR, 0.09-0.12] vs. 0.07 [IQR, 0.06-0.09], P = 0.02). Median cSUVmax and TBR increased by 92% (range, 33%-225%) and 80% (range, 20%-177%), respectively. Conclusion: Blood-pool activity decreases on delayed imaging, facilitating the assessment of 18F-NaF uptake in coronary plaques. Median TBR increases by 80%, leading to the detection of more plaques with significant uptake than are detected using the standard 1-h protocol. A greater than 1-h delay may improve the detection of 18F-NaF uptake in coronary artery plaques.

Feasibility of Coronary 18F-Sodium Fluoride Positron-Emission Tomography Assessment With the Utilization of Previously Acquired Computed Tomography Angiography.

BACKGROUND: We assessed the feasibility of utilizing previously acquired computed tomography angiography (CTA) with subsequent positron-emission tomography (PET)-only scan for the quantitative evaluation of 18F-NaF PET coronary uptake. METHODS AND RESULTS: Forty-five patients (age 67.1±6.9 years; 76% males) underwent CTA (CTA1) and combined 18F-NaF PET/CTA (CTA2) imaging within 14 [10, 21] days. We fused CTA1 from visit 1 with 18F-NaF PET (PET) from visit 2 and compared visual pattern of activity, maximal standard uptake (SUVmax) values, and target to background ratio (TBR) measurements on (PET/CTA1) fused versus hybrid (PET/CTA2). On PET/CTA2, 226 coronary plaques were identified. Fifty-eight coronary segments from 28 (62%) patients had high 18F-NaF uptake (TBR >1.25), whereas 168 segments had lesions with 18F-NaF TBR ≤1.25. Uptake in all lesions was categorized identically on coregistered PET/CTA1. There was no significant difference in 18F-NaF uptake values between PET/CTA1 and PET/CTA2 (SUVmax, 1.16±0.40 versus 1.15±0.39; P=0.53; TBR, 1.10±0.45 versus 1.09±0.46; P=0.55). The intraclass correlation coefficient for SUVmax and TBR was 0.987 (95% CI, 0.983-0.991) and 0.986 (95% CI, 0.981-0.992). There was no fixed or proportional bias between PET/CTA1 and PET/CTA2 for SUVmax and TBR. Cardiac motion correction of PET scans improved reproducibility with tighter 95% limits of agreement (±0.14 for SUVmax and ±0.15 for TBR versus ±0.20 and ±0.20 on diastolic imaging; P<0.001). CONCLUSIONS: Coronary CTA/PET protocol with CTA first followed by PET-only allows for reliable and reproducible quantification of 18F-NaF coronary uptake. This approach may facilitate selection of high-risk patients for PET-only imaging based on results from prior CTA, providing a practical workflow for clinical application.

Supraclavicular lymph nodes detected by 18F-FDG PET/CT in cancer patients: assessment with 18F-FDG PET/CT and sonography.

OBJECTIVE: The purposes of this study were to assess the diagnostic accuracy of 18F-FDG PET (FDG PET) for the detection of metastatic supraclavicular lymph nodes (LNs) and to propose an optimal diagnostic strategy with additional sonography, contrast-enhanced CT (CECT), or both. MATERIALS AND METHODS: One hundred supraclavicular LNs initially detected using FDG PET were examined using sonography. Regardless of the imaging findings, all 100 supraclavicular LNs underwent sonography-guided fine-needle aspiration biopsy. The maximum standardized uptake values (SUVsmax) of the supraclavicular LNs were measured, and a receiver operating characteristic (ROC) analysis was performed to determine the cutoff SUVmax. Then we evaluated the diagnostic performance of FDG PET and figured out the optimal combination of FDG PET and sonography or CECT to improve the diagnostic accuracy of the imaging studies and minimize procedures. RESULTS: In total, 86 of 100 PET-detected supraclavicular LNs were malignant. With application of the cutoff value obtained by ROC analysis (SUVmax=3.0), the diagnostic accuracy of FDG PET was 75.0% with a sensitivity of 74.4% and specificity of 78.6%. For supraclavicular LNs with an SUVmax of more than 3.0, FDG PET showed a positive predictive value of 95.5%; for supraclavicular LNs with an SUVmax of 3.0 or less, sonography excluded all false-negative FDG PET cases and showed a high negative predictive value of 100%. When sonography was selectively applied to cases with an SUVmax of 3.0 or less, the overall diagnostic accuracy increased to 92%. CONCLUSION: Our study revealed a high incidence rate of metastasis in PET-detected supraclavicular LNs in cancer patients. We believe that our proposed diagnostic workflow could decrease unnecessary diagnostic procedures in the evaluation of PET-positive supraclavicular LNs in cancer patients with reliability.

Assessment of regional GABA(A) receptor binding using 18F-fluoroflumazenil positron emission tomography in spastic type cerebral palsy.

Periventricular leukomalacia (PVL) due to hypoxic-ischemic insult to the immature brain, chorioamnionitis and maternal infection are the major etiological factors of spastic type cerebral palsy (CP). Despite advances in preventing and treating certain causes of CP, the number of patients has remained essentially unchanged and the pathophysiological mechanisms related to motor dysfunction remain poorly understood. In this study, statistical parametric mapping (SPM) analysis of cerebral gamma-aminobutyric acid (GABA) receptor PET imaging using [18F]-fluoroflumazenil showed increased GABA(A) receptor binding in the bilateral motor and visual cortices in spastic diplegia (SD) type CP patients (n = 20) compared with normal controls (n = 10). As GABA(A) receptor signaling modulates biological perception and production of movement, complex motor skills and use-dependent plasticity in the motor cortex, increased GABA(A) receptor binding in the motor cortex might play a important role in poor motor control. Decreased GABA(A) receptor binding was seen in the brain stem in SD CP patients, which appears to be related to spastic symptom.

Variable patterns of positron emission tomography in the assessment of patients with extramammary Paget's disease.

Whole body 18 F-fluorodeoxyglucose (FDG) positron emission tomography was performed for staging in 7 extramammary Paget's disease patients and 4 tests showed mild FDG uptake at the primary sites. Histologically, all 4 tumors were found to be thicker than 2 cm. Among the 4 patients, 2 showed multiple hypermetabolic foci of skeletal metastasis and lymph node involvement.

Assessment of tumor burden and treatment response by 18F-fluorodeoxyglucose injection and positron emission tomography in patients with cutaneous T- and B-cell lymphomas.

18F-Fluorodeoxyglucose (FDG)-positron emission tomography (PET) is a unique functional/metabolic imaging modality that is efficacious in nodal staging and detection of extranodal involvement for a variety of lymphomas. We report its novel use in evaluating tumor burden and response to therapy in two patients with cutaneous lymphomas. A 24-year-old woman with aggressive subcutaneous panniculitic T-cell lymphoma associated with fever, arthralgias, lymphadenopathy, mild anemia, and widespread painful lesions refractory to multiple treatment strategies exhibited intense uptake of a glucose analogue at sites of clinically apparent (and clinically imperceptible) disease. Denileukin diftitox therapy resulted in clinical remission, and a repeat PET scan failed to detect residual foci of malignancy. A 38-year-old man with a more indolent multifocal primary cutaneous follicle center B-cell lymphoma characterized by few systemic symptoms and slowly evolving lesions demonstrated only mild glucose analogue uptake at sites of disease. Remission was achieved by radiotherapy and intravenous rituximab, and confirmed by a repeat PET scan. Extracutaneous disease was not evident in either patient by this technique. These preliminary data suggest that FDG-PET may be useful in determining disease activity at the time of initial diagnosis, after treatment, and evaluating a suspected recurrence.