Diffusion MRI techniques.
Abstract
Parkinson’s disease (PD) is a degenerative neurological disorder, the origin of which remains unclear. The efficacy of treatments is limited due to the small number of remaining neurons. Diffusion magnetic resonance imaging (MRI) has revolutionized clinical neuroimaging. This noninvasive and quantitative method gathers in vivo microstructural information to characterize pathological processes that modify nervous tissue integrity. The changes in signal intensity result from the motion of the water molecules; they can be quantified by diffusivity measures. Diffusion MRI has revealed “biomarkers” in several brain regions that could be useful for PD diagnosis. These regions include the olfactory tracts, putamen, white matter, superior cerebellar peduncles, middle cerebellar peduncle, pons, cerebellum, and substantia nigra. There are encouraging preliminary data that differentiate PD from atypical parkinsonian diseases based on these microstructural changes.
Keywords
- brain imaging
- Parkinson’s disease
- diffusion MRI
- atypical parkinsonian diseases
- neuroimaging
1. Introduction
Parkinson’s disease (PD) was first described in 1817 by James Parkinson and is characterized by the selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) [1, 2, 3]. Although PD has been known for more than two centuries, its origin remains unclear. The motor symptoms in patients with PD appear when at least 50–80% of dopaminergic neurons have been lost in the substantia nigra (SN). For this reason the quantity of remaining neurons limits the efficacy of treatments. PD begins with a reduction in dopamine signaling from the SN to the basal ganglia, which causes a decrease in the neuronal excitation localized in the thalamus. This abnormal condition is reflected by the symptoms of bradykinesia (slow or difficult movements), rigidity, postural instability, resting tremor, and non-motor symptoms in conjunction with fatigue, reduced facial expressions, sleep and smell disturbances, depression, and cognitive decline [4].
Conventional magnetic resonance imaging (MRI) does not provide adequate contrast to study changes in the brain of patients with PD. Indeed, conventional 1.5 T T1- and T2-weighted sequences do not collect information for the SNpc. Hence, conventional MRI cannot detect structural lesions that cause PD and cannot differentiate PD from characteristic alterations of atypical parkinsonism diseases (APD), such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Conventional MRI neuroimaging is not specifically recommended for routine diagnosis in clinical practice of the difficulty in PD [5].
Diffusion MRI is an evolution of conventional MRI and has the potential to differentiate between PD and APD. This ability includes identifying the principal changes in the SN and the lower part of the putamen/caudate complex, the location of most nigrostriatal dopaminergic neurons. Changes in these areas in patients with PD could provide valuable information to aid in the diagnosis and assess disease progression. Diffusion MRI involves two techniques: (1) diffusion-weighted imaging (DWI) shows the change in a particular water molecule diffusing from one location to another over a given period of time estimated by the apparent diffusion coefficient (ADC). (2) Diffusion tensor imaging (DTI) is a useful method to measure the directionality of water inside living systems, which is estimated by fractional anisotropy (FA). The fundamental aims of the use of diffusion MRI in PD are: (1) to contribute to the differential clinical diagnosis between PD and APD; (2) to determine biomarkers of disease progression and, therefore, to demonstrate the usefulness of potential therapies that delay or improve disease progression; (3) to allow presymptomatic diagnosis in people with PD; and (4) to identify in advance the motor and non-motor complications.
This chapter reviews the available data on the use of diffusion MRI to determine the pathophysiological mechanisms responsible for PD and APD. This technique could be used to identify microstructural changes earlier and thus initiate treatment more quickly after PD onset. It also offers the potential to differentiate between PD and APD.
2. Basic of diffusion
Diffusion is the physical property that describes the Brownian (random) movement of water molecules in biological tissue in response to thermal energy [5]. The human body is composed of 75% water, which is located in three compartments: intravascular, intracellular, and extracellular (Figure 1). The movement of water molecules at the microscopic level of these compartments is sensitive to the diffusion sequence. Of note, it is the movement of water molecules in the extracellular space that is most useful to identify quantifiable markers that reflect tissue alterations. Microscopic displacement of water molecules occurs within brain tissue by following diffusion [7, 8]. Identifying these alterations in these movements could be useful to characterize neurodegenerative diseases, such as PD.
In 1965, Stejskal and Tanner [9] were the first to apply the property of diffusion to MR sequences. In 1980, researchers reported the first biological tissues imaged based on the principles of nuclear magnetic resonance established by Carr et al. [10]. In 1986, Le Bihan et al. developed the first diffusion image from a brain MRI [11]. In 1992, Warach et al. [12] first applied this technique to study cerebral infarction. An advantage of this technique is its noninvasive nature and it does not require ionizing radiation and paramagnetic contrast. There is a great interest in MRI use to measure water diffusion. This application could provide maps of the diffusion coefficients in tissues, particularly
2.1 Brief background of diffusion MRI
Diffusion MRI, also known as DWI, is a procedure of MRI based upon measuring the motion of water molecules within a voxel of biological tissue. Diffusion MRI detected the Brownian motion that is observed in the random or uncontrolled movement of particles in a fluid as they constantly collide with other molecules [13]. The pulsed gradient spin echo sequence, shown in Figure 2, is the most used acquisition scheme to generate diffusion weighting in an MRI image. It is also widely used to measure the displacement of water molecules in tissue. It consists of two radiofrequency (RF) pulses, one at 90° and the second at 180°, and two magnetic gradients with intensity G and pulse duration δ, before and after the 180° RF pulse.
In the MRI literature, the sequence parameters (see Figure 2) are commonly represented by a single diffusion parameter,
Diffusion MRI quantifies the motion of water molecules (see Table 1). Microstructural changes in neuronal tissue are determined by quantifying the diffusion coefficients, measured by applying a diffusion-sensitizing gradient using the isotropic signal decay formulated by Stejskal-Tanner, which is called the apparent diffusion coefficient (ADC). This measure allows for evaluating the average diffusion in the area of interest of a tissue. Isotropic diffusion refers to the lack of a preferred direction for diffusion. An example is cerebrospinal fluid in which the diffusion rate of molecules is equal in all directions [16, 17]. The ADC map is created with the mono-exponential model by applying a square noise filter to define the intensity scale based on
Diffusion imaging | Measures | Details |
---|---|---|
Diffusion-weighted imaging | Apparent diffusion coefficient (ADC), or trace (D) diffusion coefficient is a measure of the strength (velocity) of diffusion in tissue. | Isotropic diffusion are called the distance to travel by the water molecules in the tissue, without barriers that restrictand the move nor the direction. |
Diffusion tensor imaging | Fractional anisotropy | The molecules are limited to a determined direction of the tissue, generating a tensor that has three diffusion components on each axis (x, y, and z). |
DTI was first described by Basser et al. [18]. It provides information about the local tissue when diffusion depends on the direction and is restricted by the normal architecture of the brain and the neuronal tracts, a condition known as anisotropy. Hence, DTI allows for calculating fractional anisotropy (FA) [19]. Anisotropic diffusion is not equal in all directions. An example is diffusion in neural tracts, where water molecules diffuse more longitudinally along the tract than to the sides. This directionality is largely determined by the cellularity and cell integrity in the tissues [16, 17]. FA is an important measure to detect any structural change with respect to a direction defined by the neuronal tissue. DTI is a sensitive, noninvasive method to detect the early stages of PD [20]. It even differentiates microstructural changes in PD (Figures 4 and 5) [21].
3. Diagnosis of PD and APD
PD and APD are characterized by progressive dopaminergic dysfunction. Diagnosis and treatment of diseases in their early stages can be complicated [20]. While conventional MRI has provided information on these diseases (Table 2), diffusion MRI can help to provide additional information and specific biomarkers to help distinguish among them (Figures 6–8) [29].
Definition | Affected areas | Typical imaging findings |
---|---|---|
MSA including MSA-P and MSA-C [22] | The putamen and cerebellum are both affected in MSA, and nigral dopaminergic neuronal loss is observed in both MSA and PD [23]. Increased putaminal diffusivity in a patients with MSA. ADC is increased in the area of the lenticular nucleus in the patient with MSA [24]. | |
PSP is characterized by postural instability and supranuclear gaze palsy; it is sometimes called Richardson’s syndrome [25] | Pathological changes in the SCP and dentate nucleus. Extensive atrophy in the brain stem, particularly in the midbrain, and also in the basal ganglia and cortex [24] | |
CBS includes apraxia, the alien-limb phenomenon, and disturbed epicritic sensitivity [26] | The most common motor feature in CBS is asymmetrical parkinsonism affecting a limb, typically an arm. |
3.1 Diffusional MRI findings in PD
DWI and DTI provide quantifiable information to detect microstructural changes in PD. Neuronal loss alters the structural architecture of the central nervous system, producing potential biomarkers that could be assessed with imaging to diagnose PD (Table 3) (Figures 9–20) [28, 29, 32, 51, 52, 53].
Technique and region | Diffusion MRI findings | Key diffusion measures | Reference |
---|---|---|---|
DWI in olfactory tracts | Patients with PD showed significant increases in trace of diffusion (D) values in both olfactory tracts in a cohort of patients with PD versus healthy controls. Adapted from Ref. [30]. | Trace (D) >0.78 × 10−3 mm2/s Trace (D) <0.78 × 10−3 mm2/s | [30] |
DTI to show olfactory dysfunction | Understanding the neurological substrates of olfactory dysfunction in early PD could be used in combination with clinical markers. Identify evidence of white matter areas with increased/decreased connectivity in patients with PD with complete or severe loss of olfaction. | [31] | |
DWI of the putamen | PD, MSA-P, and healthy controls marked differences in putaminal ADC maps among patients. Putaminal ROIs denote descending regional ADC values. Adapted from Ref. [32]. | ADC median = 0.791 × 10−3 mm2/s ADC median = 0.698 × 10−3 mm2/s ADC median = 0.727 × 10−3 mm2/s | [32] |
DTI of the putamen | Schocke et al. [33] provided trace (D) imaging, which appears to be more accurate to separate patients with MSA-P from patients with PD, as rADC values in one direction are dependent on the slice orientation relative to the directions of fiber tracts. The ADC maps in the y-direction and z-direction clearly show the bilateral putaminal hyperintensity in a patient with MSA, indicating increased putaminal rADCs and rTrace (D) values. The putaminal hyperintensity is poorly demarcated on the ADC map in the x-direction. | Increased putaminal diffusivity: rADC in the y- and z-direction as well as trace (D) clearly show bilateral putaminal hyperintensity. rADC in the y-direction = 1.011 ± 0.196 × 10−3 mm2/s rADC in the x-direction = 0.750 ± 0.180 × 10−3 mm2/s Trace (D) = 0.926 ± 0.208 × 10−3 mm2/s rADC in the y-direction = 0.766 ± 0.036 × 10−3 mm2/s rADC in the x-direction = 0.591 ± 0.0058 × 10−3 mm2/s Trace (D) = 0.718 ± 0.030 × 10−3 mm2/s rADC in the y-direction = 0.769 ± 0.025 × 10−3 mm2/s rADC in the x-direction = 0.637 ± 0.071 × 10−3 mm2/s Trace (D) = 0.745 ± 0.024 × 10−3 mm2/s | [33] |
DTI of white matter | Significant differences between patients with MSA-P and patients with PD. | rADC in the y-direction = 0.833 ± 0.067 × 10−3 mm2/s ( rADC in the y-direction = 0.769 ± 0.052 × 10−3 mm2/s ( rADC in the y-direction = 0.733 ± 0.039 × 10−3 mm2/s ( | [33] |
DTI of the caudate nucleus | Significant differences in trace (D) of the caudate nucleus between patients with MSA-P and patients with PD. The caudate nucleus also shows significant differences in the rADC in the y-direction between patients with MSA-P or PD and healthy controls. | Trace (D) = 0.725 ± 0.035 × 10−3 mm2/s Trace (D) = 0.802 ± 0.125× 10−3 mm2/s rADC in y-direction = 0.808 ± 0.043× 10−3 mm2/s rADC in y-direction = 0.914 ± 0.120× 10−3 mm2/s rADC in y-direction = 0.823 ± 0.051× 10−3 mm2/s | [33] |
DTI of the globus pallidus | Significant differences:
| rADC in the z-direction = 0.829 ± 0.109× 10−3 mm2/s rADC in the z-direction = 0.737 ± 0.049× 10−3 mm2/s rADC in the z-direction = 0.798 ± 0.068× 10−3 mm2/s rADC in the x-direction = 0.879 ± 0.120× 10−3 mm2/s rADC in the x-direction = 0.736 ± 0.108× 10−3 mm2/s rADC in the x-direction = 0.721 ± 0.092× 10−3 mm2/s Trace (D) = 0.802 ± 0.125× 10−3 mm2/s Trace (D) = 0.725 ± 0.035× 10−3 mm2/s Trace (D) = 0.747 ± 0.034× 10−3 mm2/s | [33] |
DWI of the SCP ADC differentiates between patients with PSP and patients with PD | Median rADC = 0.98 × 10−3 mm2/s Median rADC = 0.79 × 10−3 mm2/s ( Median rADC = 0.79 × 10−3 mm2/s ( Median rADC = 0.80 × 10−3 mm2/s ( | [34, 35] | |
DTI of the putamen in patients with MSA-P | Putaminal trace (D) in patients with MSA-P has been mapped at the level of the mid-striatum. The diffuse hyperintensity corresponding to increased trace (D) in the putaminal region of the patient with MSA [36]. | Trace (D) >0.80 × 10−3 mm2/s Trace (D) >0.80 × 10−3 mm2/s | [37] |
DWI of the middle cerebellar peduncle to differentiate between patients with MSA-P, PSP or PD | Increased middle cerebellar peduncle rADC. The images show patients with MSA without cruciform hyperintensity and patients with MSA with cruciform hyperintensity [37]. | Increased middle cerebellar peduncle rADC differentiates patients with MSA-P from patients with PSP and PD. Median rADC = 0.93 × 10−3 mm2/s ( Median rADC = 0.82 × 10−3 mm2/s Median rADC = 0.79 × 10−3 mm2/s ( Median rADC = 0.81 × 10−3 mm2/s ( | [38] |
DWI of the middle cerebellar peduncle and rostral pons to differentiate between patients with MSA-P, PSP, or PD (caudal and rostral) | The optimal cut-off level to discriminate patients with MSA-P from patients with PSP was a middle cerebellar peduncle rADC of ≥0.733 × 10−3 mm2/s (sensitivity = 91%, specificity = 84%). ADC measurements may have been utilized as surrogate markers in trials of disease-modifying medications [38]. | Increased rADC in the middle cerebellar peduncle and rostral pons in patients with MSA-P compared with patients with PSP or PD. rADC = 0.785 ± 0.090 × 10−3 mm2/s rADC = 0.845 ± 0.133 × 10−3 mm2/s rADC = 0.771 ± 0.101 × 10−3 mm2/s rADC = 0.763 ± 0.079 × 10−3 mm2/s rADC = 0.745 ± 0.110 × 10−3 mm2/s | [39] |
DWI of the putamen and SCP | Significantly higher SCP ADC in patients with PSP compared with patients with CBS or PD and healthy controls. The median ADC in the higher-valued hemisphere was significantly increased in patients with CBS. The hemispheric symmetry ratio in patients with CBS was lower than in patients with RS or PD and healthy controls. | Putaminal ADC provides good discrimination between patients with PD and patients with APD (RS and CBS). 0.77 (0.75–0.79) × 10−3 mm2/s 0.75 (0.74–0.79) × 10−3 mm2/s 0.72 (0.71–0.73) × 10−3 mm2/s 0.70 (0.69–0.71) × 10−3 mm2/s | [35] |
DTI of the pons, cerebellum, and putamen to differentiate between patients with MSA-P and patients with PD. | FA and ADC detected early pathological involvement prior to magnetic resonance signal changes in patients with MSA-P. Early FA reduction and ADC increase are likely to be associated with subtle early degenerative processes in patients with MSA-P. | Increased ADC in the pons, cerebellum, and putamen, and reduced FA in patients with MSA compared with patients with PD and healthy controls. Pons = 0.38 Cerebellum = 0.30 Putamen = 0.35 Pons = 0.98 × 10−3 mm2/s Cerebellum = 0.96 × 10−3 mm2/s Putamen = 0.83 × 10−3 mm2/s | [40] |
DTI in patients with an implanted deep brain stimulation (DBS) device. | DTI is safe and delineation of the white matter pathway is feasible for patients with PD and an implanted DBS device. | The FA of the left SN was significantly lower than that of the right SN ( | [41] |
Dopamine transporter imaging | The neuromelanin value was significantly lower and the diffusion tensor values except FA were significantly higher in the RBD and PD groups than in the healthy group. Diffusion MRI detects nigrostriatal changes in RBD and early PD. | Neuromelanin/mean diffusivity value. SNpc = 0.76/0.82 SNpc = 0.83/0.80 | [42] |
Conventional MRI DTI of the SN | The reduced volume of the SN in the patient with PD is attributable to iron deposition. FA was lower in the patient with PD than in the patient without PD (0.425 vs. 0.581), indicating a loss of neuronal integrity. | [43] | |
DTI of the SN and middle cerebellar peduncle. | FA was increased in all three subareas of the SN. | FA was increased in the three nigral subareas in patients with PD ( The right SN had higher FA than the left in all subareas ( The left middle cerebellar peduncle had increased FA ( | [44] |
DWI of the putamen. | Putaminal diffusivity measurements to distinguish MSA-P from PD. | Prominent neuronal loss in the putamen; structural damage in the putamen would lead to enhanced diffusivity. Meta-analysis showed an overall sensitivity of 90% and specificity of 93%. | [29] |
DTI of the rostral, middle and caudal SN and cerebral peduncle | Assessment of FA in the rostral, middle, and caudal regions of the SN. SN distinguishes early-stage | Decreased FA in the caudal part of the substantial nigra with increased sensitivity and specificity even between individual subjects. t = 1.5; t = 3.7; t = 11.9; | [20] |
DTI of the SN | The FA is decreased in the nigrostriatal projection in parkinsonian patients, even during the early clinical stages | Decreased FA in the ROI along a line between the SN and the lower part of the putamen/caudate complex in patients with PD, even during the early clinical stages of the disease. FA in patients with PSP was decreased in most of the ROIs except for those in the neostriatum of parkinsonian patients showed a significant decrease in FA of the subthalamic ROI beside the SN. FA in the white matter of the premotor cortices was significantly smaller in patients with PSP or advanced PD compared with healthy controls. | [45] |
DTI of the SN, red nucleus, and cerebral peduncle | FA was reduced in the rostral SN of subjects with early-stage PD. | [46] | |
DWI of the SN with increased iron (R2) | Reduction of FA inside the SN in patients with PD demonstrated a high correlation with an increase in iron. | [47] | |
DTI of the SN with increased iron (R2) | Differences between patients with PD and controls from voxel-based analysis of R2, mean diffusivity, and FA maps [48]. | Reduction of FA inside the SN demonstrated a high correlation with an increase in iron in patients with PD. | [48] |
DTI of the SN | FA in the SN based on DTI was lower in patients with PD compared with healthy controls. | [49] | |
DTI of the SN | Decreased FA in the SN is associated with the increased motor in patients with PD. | [50] | |
DTI of the SN | Decreased FA in the SN is associated with the increase of motor symptoms in patients with PD. | [21] |
4. Conclusion
Diffusion MRI, including isotropic and anisotropic techniques, has become increasingly important in the evaluation and diagnosis of patients with PD, and even in other neurodegenerative diseases. The most common quantitative biomarkers are ADC and FA. Moreover, diffusion MRI has the advantages of being noninvasive, repeatable, and quantifiable, and has the ability to localize damage. It is likely that neuroimaging methods will become important research techniques in the area of biomarkers in future. In conclusion, the parameters estimated with diffusion MRI in patients with moderate-stage PD can distinguish between patients with PD or APD and healthy controls.
Acknowledgments
Greatly appreciated to the authors who allowed the use of the images as part of the construction of the chapter and to the Chinese Academy of Sciences for supporting this publication. It is necessary to clarify that the main author was affiliated with the Universidad Manuela Beltran and the Universidad ECCI as a research professor, but it is published with the authors’ own resources without any financial interest.
References
- 1.
Braak H, Rüb U, Gai W, et al. Idiopathic Parkinson’s disease: Possible routes by which vulnerable neuronal types may be subject to neuroinvasion by an unknown pathogen. Journal of Neural Transmission. 2003; 110 :517-536 - 2.
Hodaie M, Neimat J, Lozano A. The dopaminergic nigrostriatal system and Parkinson’s disease: Molecular events in development, disease, and cell death, and new therapeutic strategies. Neurosurgery. 2007; 60 :17-28 - 3.
Braak H, Del Tredici K, Rüb U, et al. Staging of brain pathology related to sporadic Parkinson’s disease. Neurobiology of Aging. 2003; 24 :197-211 - 4.
Deutschlander AB, Konno T, Soto-Beasley AI, et al. Association of MAPT subhaplotypes with clinical and demographic features in Parkinson’s disease. Annals of Clinical Translational Neurology. 2020; 7 :1557-1563 - 5.
Politis M. Neuroimaging in Parkinson disease: From research setting to clinical practice. Nature Reviews. Neurology. 2014; 10 :708-722 - 6.
Anderson VC, Lenar DP, Quinn JF, et al. The blood-brain barrier and microvascular water exchange in alzheimer’s disease. Cardiovascular Psychiatry Neurology. 2011; 2011 . DOI: 10.1155/2011/615829. [Epub ahead of print] - 7.
Dietrich O, Biffar A, Baur-Melnyk A, et al. Technical aspects of MR diffusion imaging of the body. European Journal of Radiology. 2010; 76 :314-322 - 8.
Le Bihan D, Johansen-Berg H. Diffusion MRI at 25: Exploring brain tissue structure and function. NeuroImage. 2012; 61 :324-341 - 9.
Stejskal EO, Tanner JE. Spin diffusion measurements: Spin echoes in the presence of a time-dependent field gradient. The Journal of Chemical Physics. 1965; 42 :288 - 10.
Carr H, Purcell E. Effects of diffusion on free precession in nuclear magnetic resonance experiments. Physics Review. 1954; 94 :630-638 - 11.
LeBihan D, Breton E, Lallemand D, et al. MR imaging of intravoxel incoherent motions: Application to diffusion and perfusion in neurologic disorders. Radiology. 1986; 161 :401-407 - 12.
Warach S, Chien D, Li W, et al. Fast magnetic resonance diffusion-weighted imaging of acute human stroke. Neurology. 1992; 42 :1717-1723 - 13.
Mitchell JG, Kogure K. Bacterial motility: Links to the environment and a driving force for microbial physics. FEMS Microbiology Ecology. 2006; 55 :3-16 - 14.
Mori S. Introduction to Diffusion Tensor Imaging. Elsevier; 2007. DOI: 10.1016/B978-044452828-5/50017-X - 15.
Kon T, Mori F, Tanji K, et al. An autopsy case of preclinical multiple system atrophy (MSA-C). Neuropathology. 2013; 33 :667-672 - 16.
Jones DK. Diffusion MRI: Theory, Methods, and Applications. DOI: 10.1093/med/9780195369779.001.0001 - 17.
Chilla GS, Tan CH, Xu C, et al. Diffusion weighted magnetic resonance imaging and its recent trend-a survey. Quantitative Imaging in Medicine and Surgery. 2015; 5 :407-422 - 18.
Basser PJ, Mattiello J, Lebihan D. Estimation of the effective self-diffusion tensor from the NMR spin Echo. Journal of Magnetic Resonance - Series B. 1994; 103 :247-254 - 19.
Hagmann P, Jonasson L, Maeder P, et al. Understanding diffusion MR imaging techniques: From scalar diffusion-weighted imaging to diffusion tensor imaging and beyond. Radiographics. Oct 2006; 26 . DOI: 10.1148/rg.26si065510. [Epub ahead of print] - 20.
Vaillancourt D, Spraker M, Prodoehl J, et al. High-resolution diffusion tensor imaging in the substantia nigra of de novo Parkinson disease. Neurology. 2009; 72 :1378-1384 - 21.
Zhan W, Kang GA, Glass GA, et al. Regional alterations of brain microstructure in Parkinson’s disease using diffusion tensor imaging. Movement Disorders. 2012; 27 :90-97 - 22.
Niethammer M, Eidelberg D. Chapter five—Network imaging in parkinsonian and other movement disorders: Network dysfunction and clinical correlates. In: Politis M, editor. Imaging in Movement Disorders: Imaging in Non-Parkinsonian Movement Disorders and Dementias, Part 2. Academic Press; 2019. pp. 143-184 - 23.
Sako W, Murakami N, Izumi Y, et al. The difference in putamen volume between MSA and PD: Evidence from a meta-analysis. Parkinsonism & Related Disorders. 2014; 20 :873-877 - 24.
Lehericy S, Bensimon G, Vidailhet M. Parkinsonian Syndromes. Elsevier Inc; 2015. DOI: 10.1016/B978-0-12-397025-1.00088-9 - 25.
Williams DR, de Silva R, Paviour DC, et al. Characteristics of two distinct clinical phenotypes in pathologically proven progressive supranuclear palsy: Richardson’s syndrome and PSP-parkinsonism. Brain. 2005; 128 :1247-1258 - 26.
Boelmans K, Bodammer NC, Suchorska B, et al. Diffusion tensor imaging of the corpus callosum differentiates corticobasal syndrome from Parkinson’s disease. Parkinson Related Disorders. 2010; 16 :498-502 - 27.
Barsottini OGP, Felício AC, de Aquino CC, et al. Progressive supranuclear palsy: New concepts. Arquivos de Neuro-Psiquiatria. 2010; 68 :938-946 - 28.
Mascalchi M, Vella A, Ceravolo R. Movement disorders: Role of imaging in diagnosis. Journal of Magnetic Resonance Imaging. 2012; 35 :239-256 - 29.
Bajaj S, Krismer F, Palma J-A, et al. Diffusion-weighted MRI distinguishes Parkinson disease from the parkinsonian variant of multiple system atrophy: A systematic review and meta-analysis. PLoS One. 2017; 12 :e0189897 - 30.
Scherfler C, Schocke MF, Seppi K, et al. Voxel-wise analysis of diffusion weighted imaging reveals disruption of the olfactory tract in Parkinson’s disease. Brain. 2006; 129 :538-542 - 31.
Sobhani S, Rahmani F, Aarabi MH, et al. Exploring white matter microstructure and olfaction dysfunction in early Parkinson disease: Diffusion MRI reveals new insight. Brain Imaging and Behavior. 2019; 13 :210-219 - 32.
Schocke M, Seppi K, Esterhammer R, et al. Diffusion-weighted MRI differentiates the Parkinson variant of multiple system atrophy from PD. Neurology. 2002; 58 :575-580 - 33.
Schocke M, Seppi K, Esterhammer R, et al. Trace of diffusion tensor differentiates the Parkinson variant of multiple system atrophy and Parkinson’s disease. NeuroImage. 2004; 21 :1443-1451 - 34.
Nicoletti G, Tonon C, Lodi R, et al. Apparent diffusion coefficient of the superior cerebellar peduncle differentiates progressive supranuclear palsy from Parkinson’s disease. Movement Disorders. 2008; 23 :2370-2376 - 35.
Rizzo G, Martinelli P, Manners D, et al. Diffusion-weighted brain imaging study of patients with clinical diagnosis of corticobasal degeneration, progressive supranuclear palsy and Parkinson’s disease. Brain. 2008; 131 :2690-2700 - 36.
Seppi K, Schocke M, Mair KJ, et al. Progression of putaminal degeneration in multiple system atrophy: A serial diffusion MR study. NeuroImage. 2006; 31 :240-245 - 37.
Nicoletti G, Fera F, Condino F, et al. Imaging of middle cerebellar peduncle width: Differentiation of multiple system atrophy from purpose: Methods: Results: Conclusion. Radiology. 2006; 239 :825-830 - 38.
Paviour D, Thornton J, Lees A, et al. Diffusion-weighted magnetic resonance imaging differentiates parkinsonian variant of multiple-system atrophy from progressive supranuclear palsy. Movement Disorders. 2007; 22 :68-74 - 39.
Seppi K, Schocke MF, Prennschuetz-Schuetzenau K, Mair K, et al. Topography of putaminal degeneration in multiple system atrophy: A diffusion magnetic resonance study. Movement Disorders. 2006; 21 :847-865 - 40.
Ito M, Watanabe H, Kawai Y, et al. Usefulness of combined fractional anisotropy and apparent diffusion coefficient values for detection of involvement in multiple system atrophy. Journal of Neurology, Neurosurgery, and Psychiatry. 2007; 78 :722-728 - 41.
Li Y, He N, Zhang C, et al. Mapping motor pathways in Parkinson’s disease patients with subthalamic deep brain stimulator: A diffusion MRI Tractography study. Neurological Theraphy. 2022:659-677 - 42.
Takahashi H, Kashiwagi N, Arisawa A, et al. Imaging of the nigrostriatal system for evaluating the preclinical phase of Parkinson’s disease development: The utility of neuromelanin, diffusion MRI, and DAT-SPECT. The British Journal of Radiology. 2022; 95 :40-41 - 43.
de Oliveira RV, Pereira JS. The role of diffusion magnetic resonance imaging in Parkinson’s disease and in the differential diagnosis with atypical parkinsonism. Radiologia Brasileira. 2017; 50 :250-257 - 44.
Lenfeldt N, Larsson A, Nyberg L, et al. Fractional anisotropy in the substantia nigra in Parkinson’s disease: A complex picture. European Journal of Neurology. 2015; 22 :1408-1414 - 45.
Yoshikawa K. Early pathological changes in the parkinsonian brain demonstrated by diffusion tensor MRI. Journal of Neurology, Neurosurgery, and Psychiatry. 2004; 75 :481-484 - 46.
Modrego PJ, Fayed N, Artal J, et al. Correlation of findings in advanced MRI techniques with global severity scales in patients with Parkinson disease. Academic Radiology. 2011; 18 :235-241 - 47.
Du G, Lewis MM, Styner M, et al. Combined R2* and diffusion tensor imaging changes in the substantia Nigra in Parkinson’s disease. Movement Disorders. 2011; 26 :1627-1632 - 48.
Péran P, Cherubini A, Assogna F, et al. Magnetic resonance imaging markers of Parkinson’s disease nigrostriatal signature. Brain. 2010; 133 :3423-3433 - 49.
Chan L-L, Rumpel H, Yap K, et al. Case control study of diffusion tensor imaging in Parkinson’s disease. Journal of Neurology, Neurosurgery, and Psychiatry. 2007; 78 :1383-1386 - 50.
Prakash BD, Sitoh Y-Y, Tan LCS, et al. Asymmetrical diffusion tensor imaging indices of the rostral substantia nigra in Parkinson’s disease. Parkinsonism & Related Disorders. 2012; 18 :1029-1033 - 51.
Seppi K, Schocke MFH, Donnemiller E, Esterhammer R, Kremser C, Scherfler C, et al. Comparison of diffusion-weighted imaging and [123I]IBZM-SPECT for the differentiation of patients with the Parkinson variant of multiple system atrophy from those with Parkinson’s disease. Movement Disorders. 2004; 19 :1438-1445 - 52.
Paviour D, Price S, Stevens J, et al. Quantitative MRI measurement of superior cerebellar peduncle in progressive supranuclear palsy. Neurology. 2005; 64 :675-679 - 53.
Nicoletti G, Fera F, Condino F, et al. MR imaging of middle cerebellar peduncle width: Differentiation of multiple system atrophy from Parkinson disease. Radiology. 2006; 239 :825-830