### Abstract

We investigated the accuracy of a double-injection method for sequentially measuring cerebral blood flow (CBF) with N-isopropyl-( ^{123}I)p-iodoamphetamine (IMP) in simulation studies based on patient data and in clinical studies. The unidirectional clearance of IMP from the blood to the brain (K _{1}; nearly equal to CBF) in the first and second sessions was calculated by means of a microsphere model. The K _{1} values in the first session (K _{1} ^{I}) were calculated from C _{b}(5)/Int_C _{a} ^{I}, where C _{b}(5) and Int_C _{a}/ ^{I} are values for brain radioactivity 5 min after the first injection and for arterial blood radioactivity obtained by 5-min continuous sampling. The K _{1} values in the second session (K _{1}/ ^{II}) were calculated by means of the following four methods. Method 1: [C _{b}(t _{z} + 5) - C _{b}(t _{z})]/[Int_C _{a}/ ^{II} - C _{a}(t _{z}) × 5], where C _{b}(t _{z}+5) and C _{b}(t _{z}) are the brain radioactivity levels 5 min after the second injection and at the time the second session was started (t _{z}), respectively. Int_C _{a} ^{II} and C _{a}(t _{z}) are the arterial blood radioactivity levels obtained by 5-min continuous sampling after the second injection and at t _{z}, respectively. Method 2: [C _{b}(t _{z} + 5) - C _{b}(t _{z})]/[Int_C _{a}/ ^{I} × R], where R is the injection dose ratio. Method 3: [C _{b}(t _{z} + 5) - C _{b}(t _{z} × exp(- K _{1}/ ^{I} × 5/λ)]/Int_C _{a}/ ^{II}, where λ is the population averaged partition coefficient. Method 4: same as Method 3 except that K _{1}/ ^{I} was replaced by K _{1}/ ^{II} obtained by means of Method 2. Theoretically, Method 4 appeared to be the best of the four methods. The change in K _{1} during the second session obtained by Method 1 or 2 largely depended on R and t _{z}, whereas Method 3 or 4 yielded a more reliable estimate than Method 1 or 2, without largely depending on R and t _{z}. Since Method 2 was somewhat superior to other methods in terms of noninvasiveness and simplicity, it also had the potential for routine clinical use. The reproducibility of two sequential measurements of K _{1} was investigated with clinical data obtained without any intervention. The response of CBF to acetazolamide challenge was also assessed by the above four methods. The knowledge gained by this study may assist in selecting a method for sequentially measuring CBF with a double injection of IMP.

Original language | English |
---|---|

Pages (from-to) | 441-452 |

Number of pages | 12 |

Journal | Annals of Nuclear Medicine |

Volume | 14 |

Issue number | 6 |

Publication status | Published - 2000 |

Externally published | Yes |

### Fingerprint

### Keywords

- Cerebral blood flow
- Double-injection method
- N-isopropyl-( I)p-iodoamphetamine
- SPECT

### ASJC Scopus subject areas

- Radiology Nuclear Medicine and imaging

### Cite this

^{123}I)p-iodoamphetamine.

*Annals of Nuclear Medicine*,

*14*(6), 441-452.

**Double-injection method for sequentially measuring cerebral blood flow with N-isopropyl-( ^{123}I)p-iodoamphetamine.** / Murase, Kenya; Inoue, Takeshi; Fujioka, Hiroyoshi; Yamamoto, Yuji; Ikezoe, Junpei.

Research output: Contribution to journal › Article

^{123}I)p-iodoamphetamine',

*Annals of Nuclear Medicine*, vol. 14, no. 6, pp. 441-452.

^{123}I)p-iodoamphetamine. Annals of Nuclear Medicine. 2000;14(6):441-452.

}

TY - JOUR

T1 - Double-injection method for sequentially measuring cerebral blood flow with N-isopropyl-( 123I)p-iodoamphetamine

AU - Murase, Kenya

AU - Inoue, Takeshi

AU - Fujioka, Hiroyoshi

AU - Yamamoto, Yuji

AU - Ikezoe, Junpei

PY - 2000

Y1 - 2000

N2 - We investigated the accuracy of a double-injection method for sequentially measuring cerebral blood flow (CBF) with N-isopropyl-( 123I)p-iodoamphetamine (IMP) in simulation studies based on patient data and in clinical studies. The unidirectional clearance of IMP from the blood to the brain (K 1; nearly equal to CBF) in the first and second sessions was calculated by means of a microsphere model. The K 1 values in the first session (K 1 I) were calculated from C b(5)/Int_C a I, where C b(5) and Int_C a/ I are values for brain radioactivity 5 min after the first injection and for arterial blood radioactivity obtained by 5-min continuous sampling. The K 1 values in the second session (K 1/ II) were calculated by means of the following four methods. Method 1: [C b(t z + 5) - C b(t z)]/[Int_C a/ II - C a(t z) × 5], where C b(t z+5) and C b(t z) are the brain radioactivity levels 5 min after the second injection and at the time the second session was started (t z), respectively. Int_C a II and C a(t z) are the arterial blood radioactivity levels obtained by 5-min continuous sampling after the second injection and at t z, respectively. Method 2: [C b(t z + 5) - C b(t z)]/[Int_C a/ I × R], where R is the injection dose ratio. Method 3: [C b(t z + 5) - C b(t z × exp(- K 1/ I × 5/λ)]/Int_C a/ II, where λ is the population averaged partition coefficient. Method 4: same as Method 3 except that K 1/ I was replaced by K 1/ II obtained by means of Method 2. Theoretically, Method 4 appeared to be the best of the four methods. The change in K 1 during the second session obtained by Method 1 or 2 largely depended on R and t z, whereas Method 3 or 4 yielded a more reliable estimate than Method 1 or 2, without largely depending on R and t z. Since Method 2 was somewhat superior to other methods in terms of noninvasiveness and simplicity, it also had the potential for routine clinical use. The reproducibility of two sequential measurements of K 1 was investigated with clinical data obtained without any intervention. The response of CBF to acetazolamide challenge was also assessed by the above four methods. The knowledge gained by this study may assist in selecting a method for sequentially measuring CBF with a double injection of IMP.

AB - We investigated the accuracy of a double-injection method for sequentially measuring cerebral blood flow (CBF) with N-isopropyl-( 123I)p-iodoamphetamine (IMP) in simulation studies based on patient data and in clinical studies. The unidirectional clearance of IMP from the blood to the brain (K 1; nearly equal to CBF) in the first and second sessions was calculated by means of a microsphere model. The K 1 values in the first session (K 1 I) were calculated from C b(5)/Int_C a I, where C b(5) and Int_C a/ I are values for brain radioactivity 5 min after the first injection and for arterial blood radioactivity obtained by 5-min continuous sampling. The K 1 values in the second session (K 1/ II) were calculated by means of the following four methods. Method 1: [C b(t z + 5) - C b(t z)]/[Int_C a/ II - C a(t z) × 5], where C b(t z+5) and C b(t z) are the brain radioactivity levels 5 min after the second injection and at the time the second session was started (t z), respectively. Int_C a II and C a(t z) are the arterial blood radioactivity levels obtained by 5-min continuous sampling after the second injection and at t z, respectively. Method 2: [C b(t z + 5) - C b(t z)]/[Int_C a/ I × R], where R is the injection dose ratio. Method 3: [C b(t z + 5) - C b(t z × exp(- K 1/ I × 5/λ)]/Int_C a/ II, where λ is the population averaged partition coefficient. Method 4: same as Method 3 except that K 1/ I was replaced by K 1/ II obtained by means of Method 2. Theoretically, Method 4 appeared to be the best of the four methods. The change in K 1 during the second session obtained by Method 1 or 2 largely depended on R and t z, whereas Method 3 or 4 yielded a more reliable estimate than Method 1 or 2, without largely depending on R and t z. Since Method 2 was somewhat superior to other methods in terms of noninvasiveness and simplicity, it also had the potential for routine clinical use. The reproducibility of two sequential measurements of K 1 was investigated with clinical data obtained without any intervention. The response of CBF to acetazolamide challenge was also assessed by the above four methods. The knowledge gained by this study may assist in selecting a method for sequentially measuring CBF with a double injection of IMP.

KW - Cerebral blood flow

KW - Double-injection method

KW - N-isopropyl-( I)p-iodoamphetamine

KW - SPECT

UR - http://www.scopus.com/inward/record.url?scp=0034480091&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034480091&partnerID=8YFLogxK

M3 - Article

C2 - 11210097

AN - SCOPUS:0034480091

VL - 14

SP - 441

EP - 452

JO - Annals of Nuclear Medicine

JF - Annals of Nuclear Medicine

SN - 0914-7187

IS - 6

ER -