82Rb and [15O]H2O myocardial perfusion PET imaging: a prospective head to head comparison.

BACKGROUND: 82Rb PET and [15O]H2O PET are both validated tracers for myocardical perfusion imaging but have not previously been compared clinically. During our site's transition from 82Rb to [15O]H2O PET, we performed a head-to-head comparison in a mixed population with suspected ischemic heart disease. METHODS: A total of 37 patients referred for perfusion imaging due to suspicion of coronary stenosis were examined with both 82Rb and [15O]H2O PET on the same day in rest and during adenosine-induced stress. The exams were rated by two blinded readers as normal, regional ischemia, globally reduced myocardial perfusion, or myocardial scarring. For [15O]H2O PET, regional ischemia was defined as two neighboring segments with average stress perfusion ≤ 2.3 mL/(min·g). Further, we evaluated a total perfusion deficit (TPD) of ≥ 10% as a more conservative marker of ischemia. RESULTS: [15O]H2O PET identified more patients with regional ischemia: 17(46%) vs 9(24%), agreement: 59% corresponding to a Cohen's kappa of .31 [95%CI .08-.53], (P < .001). Using the more conservative TPD ≥ 10%, the agreement increased to 86% corresponding to a kappa of .62 [95%CI .33-.92], (P = .001). For the subgroup of patients with no known heart disease (n = 18), the agreement was 94%. Interrater agreement was 95% corresponding to a kappa of .89 [95%CI .74-1.00] (P < .001). CONCLUSIONS: In clinical transition from 82Rb to [15O]H2O PET, it is important to take into account the higher frequency of patients with regional ischemia detected by [15O]H2O PET.

Preoperative imaging in primary hyperparathyroidism: Are 11 C-Choline PET/CT and 99m Tc-MIBI/123 Iodide subtraction SPECT/CT interchangeable or do they supplement each other?

OBJECTIVE: Preoperative location of hyperfunctioning parathyroid glands (HPGs) is vital when planning minimally invasive surgery in patients with primary hyperparathyroidism (PHPT). Dual-isotope subtraction scintigraphy with 99m Tc-MIBI/123 Iodide using SPECT/CT and planar pinhole imaging (Di-SPECT) has shown high sensitivity, but is challenged by high radiation dose, time consumption and cost. 11 C-Choline PET/CT (faster with a lower radiation dose) is non-inferior to Di-SPECT. We aim to clarify to what extent the two are interchangeable and how often there are discrepancies. DESIGN: This is a prospective, GCP-controlled cohort study. PATIENTS AND MEASUREMENTS: One hundred patients diagnosed with PHPT were included and underwent both imaging modalities before parathyroidectomy. Clinical implications of differences between imaging findings and negative imaging results were assessed. Surgical findings confirmed by biochemistry and pathology served as reference standard. RESULTS: Among the 90 patients cured by parathyroidectomy, sensitivity was 82% (95% confidence interval [CI]: 74%-88%) and 87% (95% CI: 79%-92%) for Choline PET and Di-SPECT, respectively, p = .88. In seven cases at least one imaging modality found no HPG. Of these, neither modality found any true HPGs and only two were cured by surgery. When a positive finding in one modality was incorrect, the alternative modality was correct in approximately half of the cases. CONCLUSION: Choline PET and Di-SPECT performed equally well and are both appropriate as first-line imaging modalities for preoperative imaging of PHPT. When the first-line modality fails to locate an HPG, additional preoperative imaging with the alternate modality offers no benefit. However, if parathyroidectomy is unsuccessful, additional imaging with the alternate modality has merit before repeat surgery.

11C-Choline PET/CT vs. 99mTc-MIBI/123Iodide Subtraction SPECT/CT for Preoperative Detection of Abnormal Parathyroid Glands in Primary Hyperparathyroidism: A Prospective, Single-Centre Clinical Trial in 60 Patients.

BACKGROUND: In patients with primary hyperparathyroidism (PHPT) locating hyperfunctioning glands (HPGs) is crucial when planning minimally invasive surgery. Dual-isotope subtraction scintigraphy with 99mTc-MIBI/123Iodide using SPECT/CT and planar pinhole imaging (Method A) has previously shown a sensitivity >93%. However, the method is costly and time consuming and entails a high radiation dose. 11C-Choline PET/CT (Method B) is an appealing candidate method unencumbered by these disadvantages. METHODS: Sixty patients with newly diagnosed PHPT participated and were scanned using both methods prior to parathyroidectomy. We investigated whether sensitivities of Method A and Method B are similar in a method-to-method comparison when using surgical findings as the true location. RESULTS: At the patient level, sensitivities were (A) 0.98 (95% CI: 0.90-1.00) and (B) 1.00 (95% CI: 0.93-1.00). At the gland level, sensitivities were (A) 0.88 (95% CI: 0.78-0.94) and (B) 0.87 (95% CI: 0.76-0.92). With a non-inferiority margin of ∆ = -0.1, we found a 1-sided p-value < 0.001. CONCLUSION: Our methods comparison study found that sensitivity of Method B was not inferior to Method A. We suggest that 11C-Choline PET/CT is a clinically relevant first-choice candidate for preoperative imaging of PHPT and that Method B can likely replace Method A in the near future.