The Utility of the Combined Use of 123I-FP-CIT and 123I-MIBG Myocardial Scintigraphy in Differentiating Parkinson's Disease from Other Parkinsonian Syndromes

Abstract

Background: ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy and ¹²³I-FP-CIT dopamine transporter single photon emission computed tomography (DAT-SPECT) provide specific information that distinguish Parkinson's disease (PD) from parkinsonian syndromes other than PD (non-PD), including atypical parkinsonian disorder (APD) and non-PD other than APD (nPD-nAPD). The purpose of this study was to determine whether combining DAT-SPECT and MIBG myocardial scintigraphy using multiparametric scoring system (MSS) could improve diagnostic test accuracy in discriminating PD from APD or discriminating PD from nPD-nAPD.

Methods: A total of 52 patients, including 36 PD, eight APD and eight nPD-nAPD, underwent both MIBG myocardial scintigraphy and DAT-SPECT, were evaluated. The heart-to-mediastinum (H/M) ratios (early and delayed), washout-rate (WR), the average (Ave) and asymmetry index (AI) of specific binding ratio (SBR) were calculated. Cutoff values were determined, using ROC analysis, for discriminating PD from APD and for discriminating PD from nPD-nAPD, on five parameters. All cases were scored as either 1 (PD) or 0 (nPD-nAPD or APD) for each parameter according to its threshold in each discrimination. These individual scores were summed for each case, yielding a combined score to obtain a cutoff value for the MSS in each discrimination.

Results: For discriminating PD from nPD-nAPD, the highest accuracy was 80% at a cutoff value of 19% for the WR and a cut off value of 2 improved diagnostic accuracy to 84% for MSS. For discriminating PD from APD, the highest accuracy was 86% at a cutoff value of 2.8 for the H/M ratio (late) and a cut off value of 2 showed diagnostic accuracy of 86% for MSS.

Conclusion: A MSS has comparable or better accuracy compared to each parameter of MIBG myocardial scintigraphy and DAT-SPECT in distinguishing PD from nPD-nAPD or distinguishing PD from APD.

Keywords: 123I-FP-CIT; 123I-MIBG; Parkinson’s disease; combined analysis.

Fig. 1.

Scatterplots of the H/M ratio (early), H/M ratio (delayed), WR, Ave-SBR and AI-SBR. ACC, accuracy; AI, asymmetry index; APD, atypical parkinsonian disorder; Ave, average; CO, cutoff; H/M, heart to mediastinum ratio; MM, mild to moderate; nPD-nAPD, parkinsonian syndromes other than PD or APD; PD, Parkinson’s disease; S, severe; SBR, specific binding ratio; WR, washout rate.

Fig. 2.

Example images of DAT-SPECT and MIBG myocardial scintigraphy (early and delayed) for nPD-nAPD (A–C), APD (D–F), MM-PD (G–I) and S-PD (J–L) patients. (A–C) A 78-year-old man with vascular parkinsonian syndrome. Normal uptakes on both DAT-SPECT (A) and MIBG myocardial scintigraphy [early in (B) and delayed in (C)]. Values of 6.66% (score 0) for the Ave-SBR, 3.6% (score 0) for the AI-SBR, 2.71 (score 0) for the H/M ratio (early), 3.1 (score 0) for the H/M ratio (delayed) and 11.2% (score 0) for the WR are scored as 0 on MSS for discriminating nPD-nAPD from PD. The score 0 on MSS is correctly classified as nPD-nAPD. (D–F) A 69-year-old man with PSP. Moderate low uptakes on DAT-SPECT (D) and normal uptakes on MIBG myocardial scintigraphy [early in (E) and delayed in (F)]. Values of 4.06% (score 0) for the Ave-SBR, 15.5% (score 1) for the AI-SBR, 2.76 (score 0) for the H/M ratio (early), 2.9 (score 0) for the H/M ratio (delayed) and 19.1% (score 0) for the WR are scored as 1 on MSS for discriminating PD from APD. The score 1 on MSS is correctly classified as APD. (G–I) A 64-year-old woman with MM-PD. Moderate low uptakes on both DAT-SPECT (G) and MIBG myocardial scintigraphy [early in (H) and delayed in (I)]. Values of 5.89 % (score 0) for the Ave-SBR, 21.1% (score 1) for the AI-SBR, 1.98 (score 1) for the H/M ratio (early), 1.9 (score 1) for the H/M ratio (delayed) and 27.1% (score 1) for the WR are scored as 4 on MSS for discriminating PD from APD. The score 4 on MSS is correctly classified as PD. (J–L) A 83-year-old man with S-PD. Severe low uptakes on both DAT-SPECT (J) and MIBG myocardial scintigraphy [early in (K) and delayed in (L)]. Values of 2.7 % (score 1) for the Ave-SBR, 0.4% (score 1) for the AI-SBR, 1.78 (score 1) for the H/M ratio (early), 1.38 (score 1) for the H/M ratio (delayed) and 32.3% (score 1) for the WR are scored as 5 on MSS for discriminating PD from APD. The score 5 on MSS is correctly classified as PD. AI, asymmetry index; APD, atypical parkinsonian disorder; Ave, average; DAT-SPECT, ¹²³I-FP-CIT dopamine transporter single photon emission computed tomography; H/M, heart-to-mediastinum; ¹²³I-FP-CIT, N-v-fluoro-propyl-2b-carbomethoxy-3b-(4-¹²³I-iodophenyl)nortropane; MIBG, ¹²³I-metaiodobenzylguanidine; MM, mild to moderate; MSS, multiparametric scoring system; nPD-nAPD, parkinsonian syndromes other than PD or APD; PD, Parkinson’s disease; S, severe; SBR, specific binding ratio; WR, washout-rate.