Analysis of quantitative [I-123] mIBG SPECT/CT in a phantom and in patients with neuroblastoma

Abstract

Purpose:To determine the accuracy of quantitative SPECT, intersystem and interpatient standardized uptake value (SUV) calculation consistency for a manufacturerindependent quantitative SPECT/CT reconstruction algorithm, and the range of SUVs of normal and neoplastic tissue. Methods: A NEMA body phantom with 6 spheres (ranging 10-37 mm) was filled with a known activity-to-volume ratio and used to determine the contrast recovery coefficient (CRC) for each visible sphere, and the measured SUV accuracy of those spheres and background water solution. One hundred eleven 123Imetaiodobenzylguanidine ([I-123] mIBG) SPECT/CT examinations from 43 patients were reconstructed using SUV SPECT® (HERMES Medical Solutions Inc.); 42 examinations were acquired using a GE Infinia Hawkeye 4 SPECT/CT, and 69 were acquired on a Siemens Symbia Intevo SPECT/CT. Inter scanner SUV analysis of 9 regions of normal [I-123] mIBG tissue uptake was conducted. Intrapatient mean SUV variability was calculated by measuring normal liver uptake within patients scanned on both cameras. The intensity of uptake by neoplastic tissue in the images was quantified using maximum SUV and, if present, compared over time. Results: The phantom results of the visible spheres and background resulted in accuracy calculations better than 5-10% with CRC correction. Interscanner SUV variability showed no statistical difference (average p value 0.559; range 0.066-1.0) among the 9 normal tissues analyzed. Intrapatient liver mean SUV varied ≤ 16% as calculated for 28 patients (87 examinations) studied on both scanners. In one patient, a thoracic tumor evaluated over 10 time points (18 months) underwent a 74% (3.1/12.0) reduction in maximum SUV with treatment. Conclusion: The results demonstrate quantitative accuracy to better than 10%, and both consistent SUV calculation between 2 different SPECT/CT scanners for 9 tissues, and low intrapatient measurement variability for quantitative SPECT/CT analysis in a pediatric population with neuroblastoma. Quantitative SPECT/CT offers the opportunity for objective analysis of tumor response using [I-123] mIBG by normalizing the uptake to injected dose and patient weight, as is done for PET.

Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification: a Monte Carlo study

“…The author reported an activity quantification error of 35.0% for the kidney, when no compensation for PVE was applied. Brady et al [ 12 ] reported 123 I activity quantification errors of 10.0% for spheres with volumes ranging between 5.8 mL and 29.0 mL.…”

123I-Meta-Iodobenzylguanidine Single-Photon Emission Computerized Tomography/Computerized Tomography Scintigraphy in the Management of Neuroblastoma

“…The SUV estimated on the SPECT/CT dataset can be valuable to monitor changes in the mIBG avidity of the primary tumor after chemotherapy[ 29 ] [ Figure 4 ].…”

Evaluation of Iodine-123 and Iodine-131 SPECT Activity Quantification: A Monte Carlo Study

“…High-energy (HE) collimators with thicker septa are needed when imaging 131 I due to the relatively high primary photon energy of 364.5 keV, used for imaging, and because of the otherwise high septal scatter and penetration from the emission of the 636.9 keV and 722.9 keV photons (11). However, 123 I imaging can be performed with either a low energy high resolution (LEHR) or a medium energy (ME) collimator (12)(13)(14). The ME collimator reduces the septal penetration and scatter from the higher-energy photons of 123 I, resulting in improved image contrast and more accurate activity quantification.…”