CT-based quantitative SPECT for the radionuclide 201Tl: experimental validation and a standardized uptake value for brain tumour patients

Abstract

We have previously reported on a method for reconstructing quantitative data from 99mTc single photon emission computed tomography (SPECT) images based on corrections derived from X-ray computed tomography, producing accurate results in both experimental and clinical studies. This has been extended for use with the radionuclide 201Tl. Accuracy was evaluated with experimental phantom studies, including corrections for partial volume effects where necessary. The quantitative technique was used to derive standardized uptake values (SUVs) for 201Tl evaluation of brain tumours. A preliminary study was performed on 26 patients using 201Tl SPECT scans to assess residual tumour after surgery and then to monitor response to treatment, with a follow-up time of 18 months. Measures of SUVmax were made following quantitative processing of the data and using a threshold grown volume of interest around the tumour. Phantom studies resulted in the calculation of concentration values consistently within 4% of true values. No continuous relation was found between SUVmax (post-resection) and patient survival. Choosing an SUVmax cut-off of 1.5 demonstrated a difference in survival between the 2 groups of patients after surgery. Patients with an SUVmax <1.5 had a 70% survival rate over the first 10 months, compared with a 47% survival rate for those with SUVmax >1.5. This difference did not achieve significance, most likely due to the small study numbers. By 18 months follow-up this difference had reduced, with corresponding survival rates of 40% and 27%, respectively. Although this study involves only a small cohort, it has succeeded in demonstrating the possibility of an SUV measure for SPECT to help monitor response to treatment of brain tumours and predict survival.

In vivo quantification of 177Lu with planar whole-body and SPECT/CT gamma camera imaging

“…These results with 177 Lu are consistent with previous publications that have tested the accuracy of SPECT reconstructions using diagnostic imaging radionuclides such as 99m Tc, 123 I and 201 Tl [ 2 , 7 – 9 , 15 , 16 , 21 – 24 ].…”

“…The methodology that we have developed and previously reported for quantitative SPECT [ 2 , 7 – 9 ] has been adapted for imaging the 177 Lu distribution in vivo, with appropriate modifications for the radionuclide. This uses the CT scan with conversion from Hounsfield units to attenuation coefficients for attenuation correction and for transmission-dependent scatter correction [ 10 ].…”

Extrastriatal binding of [123I]FP-CIT in the thalamus and pons: gender and age dependencies assessed in a European multicentre database of healthy controls

“…To obtain a high level of standardization of scans with different camera systems and to reduce partial volume effects when evaluating small structures such as the pons, all scans were corrected for 1. Attenuation: Chang method [38] with automatically generated ellipses, and an attenuation coefficient μ of 0.146 has been used, the high value for μ corresponding to the "narrow beam attenuation coefficient" that is recommended when scatter correction is applied [39]. 2.…”

The Advents of Hybrid Imaging Modalities: A New Era in Neuroimaging Applications

“…Kathy Willowson et al, had proposed a method to improve and confirm a quantitative technique for SPECT, based on CT. This was done to find out the practicality of this method being imposed on SPECT images of brain tumor with a developing SUV . They concluded that their method is a very feasible method of quantifying the SPECT data.…”