Radioembolization with 90Y glass microspheres for hepatocellular carcinoma: significance of pretreatment 11C-acetate and 18F-FDG PET/CT and posttreatment 90Y PET/CT in individualized dose prescription.

PURPOSE: The aim of this study was to establish an algorithm for the prescription of 90Y glass microsphere radioembolization (90Y-GMRE) of HCC in individual patients based on the relationship between tumour dose (TD) and response validated by 90Y PET/CT dosimetry and dual-tracer PET/CT metabolic parameters. METHODS: The study group comprised 62 HCC patients prospectively recruited for 90Y-GMRE who underwent pretreatment dual-tracer (11C-acetate and 18F-FDG) PET/CT as surrogate markers of HCC cellular differentiation. Pretreatment tumour-to-nontumour ratio on 99mTc-MAA SPECT/CT (T/NTMAA) was correlated with posttreatment 90Y PET/CT T/NT90Y after quantification validation. The TD-response relationship for HCC of different tracer groups was assessed on follow-up PET/CT 2 months after treatment. RESULTS: 90Y PET/CT was accurate in the measurement of recovery of injected 90Y activity (81.9-99.9%, median 94.8%). Pretreatment SPECT/CT T/NTMAA was strongly correlated with posttreatment 90Y PET/CT T/NT90Y (5.6 ± 3.2 versus 5.9 ± 3.5, T/NT90Y 1.01 × T/NTMAA + 0.161, r = 0.918, P < 0.05). The response rates were 72.4% (21/29), 70.6% (12/17) and 25% (4/16) for well, moderately and poorly differentiated HCC, respectively. The cut-off TD for a good response was significantly different between poorly differentiated and well/moderately differentiated HCC (262 Gy versus 152/174 Gy) with 89.2% sensitivity and 88% specificity. At a limiting tolerated liver dose of 70 Gy, the T/NTMAA thresholds for predicting a good response in poorly differentiated and well/moderately differentiated HCC were 3.5 and 2.0/2.3. Disregarding HCC cellular differentiation, the cut-off TD became 170 Gy, with lower sensitivity (70.3%) and specificity (76%). CONCLUSION: 90Y PET/CT can provide accurate dosimetry for 90Y-GMRE. Pretreatment T/NTMAA predicts posttreatment T/NT90Y. The TD thresholds for a good response are tracer-dependent, with a strong correlation between HCC radiosensitivity and cellular differentiation and other PET-based parameters. These cytokinetic factors improve treatment efficacy while minimizing organ damage for the prescription of personalized 90Y-GMRE.

Diagnosis of Seronegative Rheumatoid Arthritis by 68 Ga-FAPI PET/CT.

Early diagnosis of rheumatoid arthritis with the initiation of disease-modifying antirheumatic drugs is important to prevent future disability. Seronegative rheumatoid arthritis lacks the classical immunological markers, thus imposing clinical diagnostic difficulty. In this case, we reported 68 Ga-FAPI PET/CT findings of seronegative rheumatoid arthritis in a 60-year-old lady. This case illustrates how 68 Ga-FAPI PET/CT aids in the diagnosis of seronegative rheumatoid arthritis.

Significant Value of 11C-Acetate and 18F-Fluorodeoxyglucose PET/Computed Tomography on 90Y Microsphere Radioembolization for Hepatocellular Carcinoma.

Pretreatment dual-tracer (18F-fluorodeoxyglucose and 11C-acetate) PET/computed tomography (CT) has potential to predict treatment response for 90Y microsphere radioembolization (RE) in patients with inoperable hepatocellular carcinoma (HCC). Patients with 11C-acetate-avid HCC have a better response to 90Y microsphere RE, and possibly better survival. Pretreatment dual-tracer PET/CT has a significant theranostic value on 90Y microsphere RE in determining target tumor dose for HCCs with different cellular differentiation, metabolic tumor volume, and functioning liver volume, and can be used to prescribe individual injected activity of 90Y microspheres.

68Ga-DOTATOC and 68Ga-PSMA PET/CT Unmasked a Case of Prostate Cancer With Neuroendocrine Differentiation.

A bedridden 90-year-old man with fever and elevated prostate-specific antigen (PSA) (49 ng/mL) was referred for differentiation between infection and tumor. F-FDG PET/CT was negative for infection, but Ga-PSMA PET/CT showed multiple lesions in prostate gland with infiltration to bladder wall and seminal vesicle, consistent with locally advanced prostate cancer. The lesion with the highest Ga-PSMA uptake was strongly avid for Ga-DOTATOC, suggesting neuroendocrine tumor differentiation. After hormonal therapy, PSA normalized, but chromogranin-A increased (from 251 to 398 ng/mL), inferring progression of neuroendocrine tumor differentiation. Advanced prostate cancer may require investigation for pathological neuroendocrine transformation, although PSA may suggest improvement.

(11)C-acetate PET/CT in a case of recurrent hemangiopericytoma.

Intracranial hemangiopericytoma (IHPC) is a rare tumor representing less than 1% of all CNS tumors and is often indistinguishable from meningioma on structural imaging alone. Unlike meningioma, IHPC is an aggressive tumor with the propensity for early locoregional recurrence and distant metastases. Hence, its management strategies differ greatly from that of meningioma. Some investigators have reported the potential role of multitracers (F-FDG, C-methionine, and O-H2O) PET imaging in distinguishing IHPC from meningioma. We described the findings of dual-tracer (C-acetate and F-FDG) PET/CT imaging in a histopathologically proven case of IHPC with extensive extracranial osseous metastases that showed significantly greater C-acetate avidity.

11C-acetate PET/CT for metabolic characterization of multiple myeloma: a comparative study with 18F-FDG PET/CT.

UNLABELLED: We prospectively compared (11)C-acetate with (18)F-FDG in a PET/CT evaluation of multiple myeloma (MM), specifically on diagnostic accuracy, identification of high-risk patients, and monitoring of treatment response. METHODS: Dual-tracer PET/CT was performed on 35 pathologically and clinically confirmed and untreated patients (26 with symptomatic MM, 5 with smoldering MM, and 4 with monoclonal gammopathy of unknown significance) and 20 individuals with normal marrow. RESULTS: (11)C-acetate showed significant incremental value over (18)F-FDG (84.6% vs. 57.7%) for positively identifying patients with diffuse and focal symptomatic MM, and was negative in patients with indolent smoldering MM and monoclonal gammopathy of unknown significance. Three functional parameters-number of (11)C-acetate-avid and (18)F-FDG-avid focal bone lesions and (11)C-acetate general marrow activity-strongly correlated with ß-2-microglobulin as surrogate imaging markers of tumor burden. After induction chemotherapy, the metabolic change in (11)C-acetate general marrow activity correlated with clinical response. CONCLUSION: Metabolic characterization of MM in diagnosis, risk stratification, and treatment monitoring can be done more accurately by assessing lipid metabolism with (11)C-acetate than by assessing glucose metabolism with (18)F-FDG.