Added value of early-phase SPECT over planar acquisition in bone imaging.

BACKGROUND: The aim of this study is to evaluate the added value of early bone single photon emission computed tomography (SPECT) by comparison to pseudoplanar imaging. METHODS: Fifty patients were retrospectively included from 3 centers. Reading sessions were organized using: late-phase acquisition alone; early SPECT and late-phase acquisition; early pseudoplanar and late-phase acquisition. The comparison between early SPECT and MIP was performed using a McNemar Test. Patients for whom early SPECT had provided additional information were also compared with patients for whom early SPECT had not. RESULTS: Fifty patients were included. Early SPECT was superior to pseudoplanar MIP in 10/50 patients (20.0%, P=0.044). No significant difference was found between this group and the remainder. Early SPECT changed the diagnosis established from late-phase imaging in 21/50 patients. CONCLUSIONS: Early SPECT is a promising tool in bone imaging and change the diagnosis in one fifth of the cases by comparison to pseudoplanar imaging.

Blood pool SPECT: rheumatological and orthopedic focus, a pictorial essay.

Single photon emission computed tomography (SPECT) has revolutionized delayed bone scan acquisitions and promises to bring the same benefits to early acquisitions, especially in areas of complex anatomy. To date, however, only a few studies have been published about the utility of blood pool SPECT. The accurate assessment of inflammatory processes can be an indisputable added value to the diagnosis. We present here a series of clinical cases illustrating the utility of blood pool SPECT in various clinical situations in rheumatology and orthopedics. We grouped the cases according to three patterns that facilitate clinical reasoning: inflammatory osseous pathology (pattern A), inflammatory para-osseous pathology (pattern B) and inflammatory extra-osseous pathology (pattern C). A total of seventeen clinical cases are presented. This new semiology requires time and effort to be mastered but expands the diagnostic range offered by bone scintigraphy. More prospective studies on blood pool SPECT will be needed, especially those aiming to clarify its role.

Comparison of Volumetric Quantitative PET Parameters Before and After a CT-Based Elastic Deformation on Dual-Time 18FDG-PET/CT Images: A Feasibility Study in a Perspective of Radiotherapy Planning in Head and Neck Cancer.

BACKGROUND: The use of 18FDG-PET/CT for delineating a gross tumor volume (GTV, also called MTV metabolic tumor volume) in radiotherapy (RT) planning of head neck squamous cell carcinomas (HNSCC) is not included in current recommendations, although its interest for the radiotherapist is of evidence. Because pre-RT PET scans are rarely done simultaneously with dosimetry CT, the validation of a robust image registration tool and of a reproducible MTV delineation method is still required. OBJECTIVE: Our objective was to study a CT-based elastic registration method on dual-time pre-RT 18FDG-PET/CT images to assess the feasibility of PET-based RT planning in patients with HNSCC. METHODS: Dual-time 18FDG-PET/CT [whole-body examination (wbPET) + 1 dedicated step (headPET)] were selected to simulate a 2-times scenario of pre-RT PET images deformation on dosimetry CT. ER-headPET and RR-headPET images were, respectively, reconstructed after CT-to-CT rigid (RR) and elastic (ER) registrations of the headPET on the wbPET. The MTVs delineation was performed using two methods (40%SUVmax, PET-Edge). The percentage variations of several PET parameters (SUVmax, SUVmean, SUVpeak, MTV, TLG) were calculated between wbPET, ER-headPET, and RR-headPET. Correlation between MTV values was calculated (Deming linear regression). MTVs intersections were assessed by two indices (OF, DICE) and compared together (Wilcoxon test). Additional per-volume analysis was evaluated (Mann-Whitney test). Inter- and intra-observer reproducibilities were evaluated (ICC = intra-class coefficient). RESULTS: 36 patients (30M/6F; median age = 65 y) were retrospectively included. The changes in SUVmax, SUVmean and SUVpeak values between ER-headPET and RR-headPET images were <5%. The variations in MTV values between ER-headPET and wbPET images were -6 and -3% with 40%SUVmax and PET Edge, respectively. Their correlations were excellent whatever the delineation method (R2 > 0.99). The ER-headPET MTVs had significant higher mean OF and DICE with the wbPET MTVs, for both delineation methods (p ≤ 0.002); and also when lesions had a volume > 5cc (excellent OF = 0.80 with 40%SUVmax). The inter- and intra-observer reproducibilities for MTV delineation were excellent (ICC ≥ 0.8, close to 1 with PET-Edge). CONCLUSION: Our study demonstrated no significant changes in MTV after an elastic deformation of pre-RT 18FDG-PET/CT images acquired in dual-time mode. This opens possibilities for HNSCC radiotherapy planning improvement by transferring GTV-PET on dosimetry CT.

Blood-Pool SPECT/CT in Chronic Ankle Tendinopathy.

We report 2 cases where blood-pool SPECT/CT had a high added value compared with standard 3-phase bone scintigraphy with only delayed SPECT/CT for the etiological diagnosis of painful ankles. Two men, aged 48 and 62 years, were referred for suspicions of medial and lateral malleoli stress fractures, respectively. Although standard planar blood-pool imaging and delayed SPECT/CT were inconclusive, blood-pool SPECT/CT showed markedly increased uptake along posterior tibial tendon and peroneal tendon, respectively, leading to diagnose tendonitises. These cases illustrate that blood-pool SPECT/CT can extend the diagnostic yield of bone scintigraphy to extraosseous origin, particularly in chronic lower extremities pain.

Personalized dosimetry with intensification using 90Y-loaded glass microsphere radioembolization induces prolonged overall survival in hepatocellular carcinoma patients with portal vein thrombosis.

UNLABELLED: The objective of this study was to evaluate the response rate and survival of hepatocellular carcinoma portal vein thrombosis (PVT) patients treated with (90)Y-loaded glass microspheres using a personalized dosimetry and intensification concept. METHODS: The microspheres were administered to 41 hepatocellular carcinoma PVT patients (main = 12; lobar/segmental = 29). (99m)Tc-macroaggregated albumin SPECT/CT quantitative analysis was used to calculate the tumor dose (TD), healthy injected liver dose (HILD), and injected liver dose (ILD). Response was evaluated at 3 mo using the criteria of the European Association for the Study of the Liver, with CT follow-up lasting until disease progression or death. Survival was assessed using the Kaplan-Meier method. RESULTS: The mean injected activity was 3.1 ± 1.5 GBq, and mean ILD was 143 ± 49 Gy. When a TD threshold of 205 Gy was applied, (99m)Tc-macroaggregated albumin SPECT/CT achieved a 100% sensitivity and 90% overall accuracy (0 false-negatives; 4 false-positives) in response prediction. On the basis of TD and HILD values, 37% of patients received an intensification of the treatment (increased injected activity with the aim of achieving a TD ≥ 205 Gy and HILD < 120 Gy, applying an ILD > 150 Gy). This intensification resulted in a high response rate (85%) without increased liver toxicity of grade 3 or higher (6% vs. 12% in the patients who did not receive treatment intensification; not statistically significant). For the total 41 patients, median overall survival (OS) was 18 mo (95% confidence interval, 11-25 mo). For patients with a TD of less than 205 Gy, median OS was 4.3 mo (3.7-5 mo), versus 18.2 mo (8.5-28.7 mo) for those with a TD of 205 Gy or more (P = 0.005). Median OS was 20.9 mo for patients with a TD of 205 Gy or more and good PVT targeting (n = 36). OS was 12 mo (3 mo to ∞) for patients with main PVT, versus 21.5 mo (12-28.7 mo) for those with segmental or lobar PVT (not statistically significant). For the 5 patients with complete portal vein revascularization who underwent lobar hepatectomy, median OS was not reached yet exceeded 24.5 mo and was significantly higher than that of other patients (P = 0.0493). CONCLUSION: Using a (99m)Tc-macroaggregated albumin SPECT/CT personalized dosimetry and intensification concept with (90)Y-loaded glass microspheres induced prolonged OS for PVT patients as compared with the standard of care (sorafenib), without increasing liver toxicity. Prospective randomized studies are therefore warranted.