Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects

Abstract

Objective: A novel multifocal collimator, IQ-SPECT (Siemens) consists of cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ( 201 Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging.Methods: Forty patients (eight women, mean age of seventy-five years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administrating 201 Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal collimator called IQ-SPECT. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT).Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all MPI studies.A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software.Results: IQ-SPECT provided good or excellent image quality. IQ-SPECT images without AC were similar to those of conventional LEHR study. Mid-inferior defect score (0.3±0.5) in conventional LEHR study was increased significantly in IQ-SPECT with AC (0±0). IQ-SPECT (AC) improved the mid-inferior decreased perfusion shown in conventional images. The apex in IQ-SPECT (AC) was decreased compared to that in LEHR (0.1±0.3 vs. 0.5±0.7, p<0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p=0.0009). Conclusion:The images of IQ-SPECT acquired in a short time are equivalent with that of conventional LEHR. The results indicated that the IQ-SPECT system with attenuation correction is capable of correcting inferior artifacts with high image quality.(Ann Nucl Med)

How to use cardiac IQ•SPECT routinely? An overview of tips and tricks from practical experience to the literature

“…The phantom study also confirmed that either the activity or the acquisition duration can be reduced. While all the previously mentioned studies used 99m Tc tracers, the technique has also been used and validated with 201 Tl [7,8]. In both studies with 201 Tl, concordance between IQ•SPECT CT and conventional parallel collimation was better when AC was used.…”

Validation of prone myocardial perfusion SPECT with a variable-focus collimator versus supine myocardial perfusion SPECT with or without computed tomography-derived attenuation correction

“…Previously, we reported that the image quality and defect decision of supine MPS images with IQ-SPECT were comparable to those of supine MPS images through a conventional collimator [9]. CTAC has been reported to reduce inferior artifacts yet preserve image quality in IQ-SPECT [10]. Images acquired by 201 Tl stress MPS with IQ-SPECT and CTAC with the patient in the supine position are accurate enough to allow the detection of coronary artery disease [11].…”

New techniques, distinctive population, unique normal databases

“…They noted that CTAC improved inferior artifacts with some apparent decrease in anterior or apical anterior segments. 22 Standard doses set by the Japanese working group for Tl-201 are 74-111 MBq (2-3 mCi), which is used in about half of the SPECT MPI studies as of 2015 due to its high extraction fraction, defect contrast, image quality, and the use of a single administration for both stress and rest. 18 Each of the studies at total of 111 MBq (3 mCi) 201 Tl was used.…”