Impact of PET data driven respiratory motion correction and BSREM reconstruction of 68Ga-DOTATATE PET/CT for differentiating neuroendocrine tumors (NET) and intrapancreatic accessory spleens (IPAS)

Abstract

To evaluate whether quantitative PET parameters of motion-corrected 68Ga-DOTATATE PET/CT can differentiate between intrapancreatic accessory spleens (IPAS) and pancreatic neuroendocrine tumor (pNET). A total of 498 consecutive patients with neuroendocrine tumors (NET) who underwent 68Ga-DOTATATE PET/CT between March 2017 and July 2019 were retrospectively analyzed. Subjects with accessory spleens (n = 43, thereof 7 IPAS) and pNET (n = 9) were included, resulting in a total of 45 scans. PET images were reconstructed using ordered-subsets expectation maximization (OSEM) and a fully convergent iterative image reconstruction algorithm with β-values of 1000 (BSREM1000). A data-driven gating (DDG) technique (MOTIONFREE, GE Healthcare) was applied to extract respiratory triggers and use them for PET motion correction within both reconstructions. PET parameters among different samples were compared using non-parametric tests. Receiver operating characteristics (ROC) analyzed the ability of PET parameters to differentiate IPAS and pNETs. SUVmax was able to distinguish pNET from accessory spleens and IPAs in BSREM1000 reconstructions (p < 0.05). This result was more reliable using DDG-based motion correction (p < 0.003) and was achieved in both OSEM and BSREM1000 reconstructions. For differentiating accessory spleens and pNETs with specificity 100%, the ROC analysis yielded an AUC of 0.742 (sensitivity 56%)/0.765 (sensitivity 56%)/0.846 (sensitivity 62%)/0.840 (sensitivity 63%) for SUVmax 36.7/41.9/36.9/41.7 in OSEM/BSREM1000/OSEM + DDG/BSREM1000 + DDG, respectively. BSREM1000 + DDG can accurately differentiate pNET from accessory spleen. Both BSREM1000 and DDG lead to a significant SUV increase compared to OSEM and non-motion-corrected data.

Improved detection of in-transit metastases of malignant melanoma with BSREM reconstruction in digital [18F]FDG PET/CT

“…2-Deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography ([ 18 F]FDG PET/CT) is typically used for the staging and restaging of high-risk melanoma patients, mainly for the detection of lymph node metastases and distant metastases. With the advent of digital PET and novel iterative reconstruction techniques, the detectability of small-sized [ 19 ] and faintly [ 18 F]FDG-avid lesions has improved considerably [ 20 , 21 ]. Hence, digital PET/CT may play a relevant role in the detection of the exact number, size, and location of ITM and may subsequently impact patient management and therapy-related decisions [ 18 , 22 – 24 ].…”

Intrapancreatic Accessory Spleen Diagnosed As Neuroendocrine Tumor: The Dangers of False Positives and Their Implications in Subsequent Management

“…Literature documents many case reports of false positives on PET-CT NETSPOT due to ectopic splenic anomalies [12][13][14][15][16][17]. One case report with a literature review showed that 66.7% of patients with intrapancreatic accessory spleen ended up undergoing unnecessary pancreatic resections [13].…”

“…While this technique could have been utilized for our patient, a biopsy was performed in lieu of other available techniques. A study by Liberini et al showed that utilization of motion correction factors in PET/CT and high standard uptake value (SUV) cut-off (suggested at 42) can also help distinguish NETs from ectopic splenic anomalies [15].…”

“…A study by Liberini et al. showed that utilization of motion correction factors in PET/CT and high standard uptake value (SUV) cut-off (suggested at 42) can also help distinguish NETs from ectopic splenic anomalies [ 15 ].…”

New PET technologies – embracing progress and pushing the limits

“…Notably, the vendor tools provide fully automated workflows that culminate with a 'simple' final 3D motion-corrected image. Using these tools, we are already seeing a new research arena with large patient cohorts being studied [44,46,51,55], providing statistical power to demonstrate a desirable evolution of quantitative and qualitative PET through the use of DDMC. Encouragingly, we are also seeing research studies branching out beyond the traditional PET motion correction focus of lung lesion quantification to address additional clinical applications, such as cardiac imaging and diagnostic tumour/organ differentiation [47,48,55,56].…”