Investigation of the new non-invasive semi-quantitative method of 123I-IMP pediatric cerebral perfusion SPECT.

Yasuharu Wakabayashi,Hiromitsu Daisaki,Kenichi Kashikura,Masafumi Sakamoto,Mayuki Uchiyama,Makoto Matsumoto,Parasuraman Padmanabhan

doi:10.1371/journal.pone.0241987

Abstract

In pediatric cases requiring quantification of cerebral blood flow (CBF) using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT), arterial blood sampling is sometimes impossible due to issues such as movement, crying, or body motion. If arterial blood sampling fails, quantitative diagnostic assessment becomes impossible despite radiation exposure. We devised a new easy non-invasive microsphere (e-NIMS) method using whole-body scan data. This method can be used in conjunction with autoradiography (ARG) and can provide supportive data for invasive CBF quantification. In this study, we examined the usefulness of e-NIMS for pediatric cerebral perfusion semi-quantitative SPECT and compared it with the invasive ARG. The e-NIMS estimates cardiac output (CO) using whole-body acquisition data after 123I-IMP injection and the body surface area from calculation formula. A whole-body scan was performed 5 minutes after the 123I-IMP injection and CO was estimated by region of interest (ROI) counts measured for the whole body, lungs, and brain using the whole-body anterior image. The mean CBF (mCBF) was compared with that acquired via ARG in 115 pediatric patients with suspected cerebrovascular disorders (age 0–15 years). Although the mCBF estimated by the e-NIMS indicated a slight deviation in the extremely low- or high-mCBF cases when compared with the values acquired using the invasive ARG, there was a good correlation between the two methods (r = 0.799; p < 0.001). There were no significant differences in the mCBF values based on physical features, such as patients’ height, weight, and age. Our findings suggest that 123I-IMP brain perfusion SPECT with e-NIMS is the simplest semi-quantitative method that can provide supportive data for invasive CBF quantification. This method may be useful, especially in pediatric brain perfusion SPECT, when blood sampling or identifying pulmonary arteries for CO estimation using the graph plot method is difficult.

Highlights

Cerebral blood flow (CBF) distribution is widely evaluated via scintigraphy in various clinical situations such as in the diagnosis of acute encephalitis and encephalopathy, detection of the abnormal blood flow accompanying cerebrovascular disorders, circulation reserve evaluation by the Acetazolamide stress test, and for understanding the neuropsychiatric disorder represented by epilepsy
The mean CBF (mCBF) was 38.9 ± 12.2 mL/100 g/min for the ARG and 39.7 ± 9.8 mL/100 g/min for easy non-invasive microsphere (e-non-invasive microsphere (NIMS)); there were no significant differences in mCBF values between the two methods
We devised the e-NIMS as a new, non-invasive, semi-quantitative approach for pediatric brain perfusion single-photon emission computed tomography (SPECT) using 123I-IMP and compared its results with those of the invasive ARG

Summary

Introduction

Cerebral blood flow (CBF) distribution is widely evaluated via scintigraphy in various clinical situations such as in the diagnosis of acute encephalitis and encephalopathy, detection of the abnormal blood flow accompanying cerebrovascular disorders, circulation reserve evaluation by the Acetazolamide stress test, and for understanding the neuropsychiatric disorder represented by epilepsy. 123I-IMP temporarily accumulates in the lungs before being rapidly released into the arteries. It accumulates at a high rate, 90% or more, in the brain tissue in the first circulation and is distributed proportionally to the regional CBF (rCBF). The microsphere method can obtain rCBF by continuous arterial blood sampling to obtain the integral value of the input function and dividing the SPECT count in the brain by the integral value of the input function. The input function of the microsphere method requires actual measurement of continuous arterial blood sampling, whereas the NIMS method measures the injection dose, lung washout rate, and cardiac output based on planar imaging counts and uses them to estimate the input function without arterial blood sampling

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Conclusion