Journal of Nuclear Cardiology最新文献

Background: Visual score (VS) on imaging with technetium-based bone-avid tracers is used to qualify myocardial tracer uptake for diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). While VS can be determined on both planar and single photon emission computed tomography (SPECT), the concordance between the 2 techniques has not been formally assessed.

Methods: Cardiac scintigraphy studies with bone-avid tracers performed between November 2017 and January 2024 were evaluated (N = 441; mean age: 73 ± 11 years, 42% women). VS was independently assessed on planar images and SPECT. Myocardial tracer uptake on SPECT was considered as the diagnostic standard.

Results: ATTR-CA was confirmed by myocardial tracer uptake on SPECT in 104 patients (24%). Among them, diffuse myocardial tracer uptake was noted in 64% of the patients, focal on diffuse in 26% of the patients and focal in 8% of the patients. When considering VS ≥ 2 on SPECT as indicative of a positive study, the sensitivity, specificity, positive predictive value, and negative predictive value of planar VS was 92%, 77%, 56%, and 98%, respectively. There was weak agreement between planar and SPECT VS (weighted kappa = 0.51).

Conclusion: There is poor concordance between VS on planar imaging and SPECT. Only SPECT VS should be used to qualify tracer uptake for the confirmation of ATTR-CA.

Background: Standard procedure involves acquiring separate computed tomography (CT) scans during rest and stress for attenuation correction of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) which results in increased radiation dose for patients. The reduction of one of the CT scans can reduce radiation exposure. We investigated whether a single post-stress CT scan can be used for attenuation correction of both stress and rest MPI SPECT without affecting clinical interpretation.

Methods: A total of 106 consecutive patients underwent diagnostic MPI SPECT-CT with ^99mTc-tetrofosmin using CT-derived attenuation data at stress and rest. We created 106 post-rest perfusion pairs of polar maps reconstructed twice with rest and post-stress CT attenuation data. The similarity between these pairs of maps was assessed in three ways: (1) mathematically, (2) subjectively by 6 independent experienced nuclear medicine physicians, and (3) by categorical analysis of the summed perfusion score (SPS) to evaluate potential changes in clinical interpretation.

Results: The Bland-Altman analysis showed no differences in SPS between the pair of maps. The t-test showed no statistically significant differences between the scores of individual myocardial segments. Physicians rated the maps' similarity on average of 9.3 (±0.8) on a scale of 1 to 10, and a function was proposed to describe physicians' predicted responses based on compared pairs of maps. A categorical analysis revealed that approximately 30% of patients changed their SPS category when using 1CT instead of 2CT and that a small subset exhibited shifts large enough to potentially influence interpretation.

Conclusions: Using a single post-stress CT for attenuation correction of both stress and rest MPI SPECT appears feasible in most cases, but careful review is recommended. The method should be applied with caution, particularly when registration quality is suboptimal or when ischemia is clinically suspected.

Background: Coronary microvascular dysfunction is implicated in ∼two-thirds of ischaemia with no obstructive coronary artery disease (INOCA) cases and is significant due to its association with a higher risk of major adverse cardiac events (MACE). While invasive techniques are the gold standard for diagnosing coronary microvascular dysfunction (CMD), positron emission tomography (PET) offers a noninvasive approach to quantifying myocardial blood flow (MBF) and detecting CMD. This study aimed to quantify myocardial flow reserve (MFR) using PET in INOCA patients to identify CMD and to correlate it with thrombolysis in myocardial infarction (TIMI) and TIMI myocardial perfusion grade (TMPG) angiographic flow grades.

Methods: Thirty INOCA patients with angiographic evidence of non-obstructive coronaries and slow flow were prospectively enrolled and underwent dynamic rest and stress cardiac ¹³N-NH₃ PET with MBF and MFR quantification. Patients with MFR values below 2.3 were classified as having CMD. Angiographic flow grades (TIMI and TMPG) were correlated with MFR and MBF.

Results: The mean global stress MBF and MFR for the study cohort were 2.54 ± 0.72 mL/minute/gm and 2.91 ± 0.81, respectively. No significant correlation was found between MFR and TIMI (r = -0.140, P = 0.108) or MFR and TMPG (r = -0.06, P = 0.446). Among the participants, 8 (27 %) had reduced global MFR less than 2.3 (mean: 1.80 ± 0.36), indicating CMD. The remaining 22 patients (73 %) had normal MFR values. Within the CMD group, 3 patients had functional CMD with elevated resting MBF, while 5 had classic CMD with blunted hyperaemic response to vasodilator stress.

Conclusions: PET is an excellent noninvasive modality for diagnosing CMD. Coronary slow flow in angiographically normal arteries does not correlate with ¹³N-NH₃ PET MFR values and is not a reliable marker for identifying CMD as indicated by the study's findings.

Background: Early diagnosis of transthyretin-amyloid cardiomyopathy (ATTR-CM) is key to early treatment initiation. Recent guidelines recommend using both single-photon emission computed tomography (SPECT) and planar imaging. However, whether combined use of planar imaging and SPECT improves diagnostic accuracy compared with histological confirmation is unclear. We assessed the significance of using both planar imaging and SPECT with bone-seeking tracer cardiac scintigraphy for diagnosing endomyocardial biopsy (EMB)-proven ATTR-CM.

Methods and results: This retrospective observational study included 117 consecutive patients with suspected ATTR-CM who underwent bone-seeking tracer cardiac scintigraphy, among whom 42 underwent EMB based on positive planar imaging (Perugini grade ≥2) and/or positive SPECT results (uptake score ≥1). Of these 42 patients, 38 (91%) were histologically diagnosed with ATTR-CM. Among patients with concordantly positive planar imaging and SPECT, 36/37 (97%) were diagnosed with ATTR-CM. Among patients with discordant findings, 2/2 (100%) with negative planar but positive SPECT findings were diagnosed with ATTR-CM, whereas 0/3 (0%) with positive planar but negative SPECT findings were diagnosed with ATTR-CM. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SPECT for detecting transthyretin amyloid deposition on EMB were 100%, 75%, 97%, 100%, and 98%, respectively. On SPECT, tracer uptake was consistently and maximally observed in the interventricular septum in all cases of EMB-proven ATTR-CM (P < 0.001).

Conclusions: SPECT has a high diagnostic ability in detecting EMB-proven ATTR-CM and effectively complements planar imaging by mitigating its limitations, reducing both false-positive and false-negative findings of planar imaging alone.

The central illustration displays the flow of study participants and the results of the primary endpoint. The individual baseline and follow-up MDS TBR are presented as red (LDMTX) or blue (Placebo) slope charts, along with the mean and standard deviation from each group at week 0 and week 24. A waterfall plot displays the absolute change in MDS TBR for each individual participant, colored by treatment group. An example of an FDG PET study of a subject with HIV who has heightened arterial inflammation that persists over time. HIV: Human immunodeficiency virus, 18F-FDG: 18F-Fluorodeoxyglucose, LDMTX: Low dose Methotrexate, PET: Positron Emission Tomography, CT: Computed Tomography, MDS: Most diseased segment, TBR: Tissue to Background.

Background: Cardiac amyloid radionuclide imaging (CARI) with ^99mTc-pyrophosphate (PYP) enables the noninvasive diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM). Recent PYP shortages have necessitated substitution with ^99mTc-hydroxymethylene diphosphonate (HMDP), yet direct comparative data are limited. We aimed to compare scan interpretation, ATTR-CM prevalence, and myocardial-to-blood pool discrimination between PYP and HMDP in real-world clinical practice.

Methods: We retrospectively analyzed 992 consecutive patients who underwent SPECT/CT for suspected ATTR-CM at a single referral center between October 2022 and January 2025. PYP was used except during two shortage periods (December 2023 to February 2024 and October 2024 to January 2025), when HMDP was substituted. Scan interpretation and final ATTR-CM diagnoses were recorded. The myocardial-to-blood-pool radiotracer uptake ratio (3D Score) was measured as a surrogate for contrast resolution.

Results: Of 992 unique patients (median age 76, 27% female), 816 received PYP and 176 (18%) received HMDP. Baseline clinical, echocardiographic, and biomarker characteristics were similar between groups. Rates of positive scans (PYP: 26%, HMDP: 25%; P = 0.95) and final ATTR-CM diagnoses (28% vs 26%; P = 0.59) were comparable. Among patients with positive scans (n = 256), HMDP yielded significantly higher 3D Scores (2.0 [1.7-2.5] vs 1.4 [1.2-1.7], P < 0.001), suggesting enhanced myocardial-to-blood pool contrast resolution.

Conclusions: In a large cohort with similar clinical profiles, HMDP provided equivalent diagnostic yield and superior myocardial-to-blood-pool discrimination compared to PYP. These findings support HMDP as a good alternative during PYP shortages, with potential advantages in contrast resolution.

Background: In suspected cardiac sarcoidosis, the interpretation of myocardial fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) can be challenging and can have important clinical implications. In this study, we aimed to study the prevalence of lateral wall FDG uptake in patients with suspected cardiac sarcoidosis, particularly in patients with ventricular pacing (V-pacing) or left bundle branch block (LBBB).

Methods: We retrospectively reviewed sarcoidosis-protocol FDG PET/CT studies performed at our center for clinical suspicion for cardiac sarcoidosis where an electrocardiogram (ECG) was available within three months of the PET/CT. We identified the absence or presence of LBBB or V-pacing on ECG, reviewed perfusion and FDG PET/CT findings, and classified all patients according to whether they met Heart Rhythm Society (HRS) criteria for cardiac sarcoidosis or probable cardiac sarcoidosis (meeting all HRS criteria except biopsy-proven disease and having extracardiac FDG uptake present). We also reviewed the results of cardiac magnetic resonance imaging (MRI) and follow-up FDG PET/CT imaging if applicable. Patients were followed until a composite endpoint of durable left ventricular assist device placement, cardiac transplant, or death.

Results: Five hundred thirty patients met inclusion criteria, 169 patients (31.9%) had V-pacing (N = 133 (78.7%)) or LBBB (N = 36 (21.3%)) on ECG, and 361 (68.1 %) had neither. Sixty-six of the 169 patients (39.1%) with V-pacing or LBBB had focal or focal-on-diffuse lateral wall myocardial FDG uptake without an associated perfusion defect, compared with 39 of the 361 patients (10.8%) without either (P < 0.001). Of the 66 patients with V-pacing/LBBB and lateral wall FDG uptake, 27 (40.9%) underwent cardiac MRI, and only six (22.2 %) had evidence of lateral wall late gadolinium enhancement (LGE). Twenty-four (36.4%) of the 66 patients had extracardiac FDG uptake, and these were the only patients with definite/probable cardiac sarcoidosis in follow-up. There was no difference in outcomes between patients with or without definite/probable cardiac sarcoidosis stratified by lateral wall myocardial FDG uptake pattern.

Conclusions: Lateral wall myocardial FDG uptake without an associated perfusion defect was significantly more common among patients with LBBB or V-pacing referred for sarcoidosis FDG PET/CT imaging than among those without LBBB or V-pacing. LBBB and V-pacing should be considered as potential causes of lateral wall myocardial FDG uptake in patients with and without biopsy-proven sarcoidosis, and diagnoses other than cardiac sarcoidosis should be considered when this pattern is present but metabolically active extracardiac sarcoidosis is absent.