Morphometric imaging and quantitative susceptibility mapping as complementary tools in the diagnosis of parkinsonisms

Abstract

Background and purpose: In the quest for in vivo diagnostic biomarkers to discriminate Parkinson's disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA, mainly p phenotype), many advanced magnetic resonance imaging (MRI) techniques have been studied. Morphometric indices, such as the Magnetic Resonance Parkinsonism Index (MRPI), demonstrated high diagnostic value in the comparison between PD and PSP. The potential of quantitative susceptibility mapping (QSM) was hypothesized, as increased magnetic susceptibility (Δχ) was reported in the red nucleus (RN) and medial part of the substantia nigra (SNImed) of PSP patients and in the putamen of MSA patients. However, disease-specific susceptibility values for relevant regions of interest are yet to be identified. The aims of the study were to evaluate the diagnostic potential of a multimodal MRI protocol combining morphometric and QSM imaging in patients with determined parkinsonisms and to explore its value in a population of undetermined cases.Method: Patients with suspected degenerative parkinsonism underwent clinical evaluation, 3 T brain MRI and clinical follow-up. The MRPI was manually calculated on T1weighted images. QSM maps were generated from 3D multi-echo T2*-weighted sequences. Results:In determined cases the morphometric evaluation confirmed optimal diagnostic accuracy in the comparison between PD and PSP but failed to discriminate PD from MSAp. Significant nigral and extranigral differences were found with QSM. RN Δχ showed excellent diagnostic accuracy in the comparison between PD and PSP and good accuracy in the comparison of PD and MSA-p. Optimal susceptibility cut-off values of RN and SNImed were tested in undetermined cases in addition to MRPI. Conclusions:A combined use of morphometric imaging and QSM could improve the diagnostic phase of degenerative parkinsonisms.

Parkinson's disease and Parkinsonism syndromes: Evaluating iron deposition in the putamen using magnetic susceptibility MRI techniques - A systematic review and literature analysis

“… Pang et al (2022) [ 78 ] 3 T/32 SWI iPD: 77/MSA-P: 75 Iron accumulation of the dorsolateral PUT → more complex in MSA-P compared with iPD. Mazzucchi et al (2022) [ 79 ] 3 T/NR QSM PD: 31/MSA-c: 9/MSA-P:5/PSP: 24 ↑ χ of the PUT → Optimal diagnostic accuracy in PD/MSA-p comparison. ↑ χ of the PUT → Effective in distinguishing PD from PSP with good accuracy, though some overlap between the two groups exists.…”

“…Additionally, Ito et al (2017) [ 95 ] and Meijer et al (2015) [ 102 ] receiver operating characteristic (ROC) analysis showed a high accuracy of posterior PUT χ in differentiating PD from MSA-P groups. Mazzucchi et al's two studies using QSM and morphometric imaging in 2019 and 2022 demonstrated that an increased χ of the PUT was effective in distinguishing between PD, MSA, and MSA-P, with good diagnostic accuracy [ 79 , 93 ]. They also found that this method was successful in differentiating PD from PSP despite some overlap between the two groups.…”

“…The majority of studies included in this review found evidence of increased iron deposition in the PUT in these patients [ 40 , 57 , 66 , [77] , [78] , [79] , [80] , [83] , [84] , [85] , [86] , [87] , [88] , [89] , [90] , [91] , [92] , [93] , [94] , [95] , [96] , [98] , [102] , [103] , [105] , 97 , 107 , 100 , 106 ]. This finding is consistent with previous studies that have shown increased iron levels in the PUT of other NDDs [ 10 , 108 , 109 ].…”

Diagnostic Performance of Putaminal Hypointensity on Susceptibility MRI in Distinguishing Parkinson Disease from Progressive Supranuclear Palsy: A Meta‐Analysis

“…In addition to the putamen, some studies indicated that the susceptibility of the red nucleus, substantia nigra, and globus pallidus could also be used to distinguish PSP from PD 15–17 . The latest study even showed that diagnostic accuracy comparing PD and PSP ranged from good (Putamen, Subthalamic nucleus) to optimal (red nucleus) 32 . However, there have been only a few related studies, which used different imaging techniques, so no unified conclusion can be drawn yet.…”

“… 15 , 16 , 17 The latest study even showed that diagnostic accuracy comparing PD and PSP ranged from good (Putamen, Subthalamic nucleus) to optimal (red nucleus). 32 However, there have been only a few related studies, which used different imaging techniques, so no unified conclusion can be drawn yet.…”