Dopamine transporter SPECT: How to remove subjectivity?

Abstract

Clinical criteria enable accurate and reliable diagnosis of parkinsonian syndromes when cardinal clinical features are fully developed. Single photon emission computed tomography (SPECT) investigating the striatal dopamine transporter (DAT) status have been suggested to increase the diagnostic accuracy in uncertain parkinsonian syndromes such as isolated tremor symptoms not fulfilling essential tremor criteria, as well as drug-induced, vascular and psychogenetic parkinsonism. Several approaches for the analysis of the striatal DAT distribution have been tested for their ability to analyze and quantify SPECT images. Visual assessment of DAT binding and semiquantitative analysis using region of interests have been recommended by Nuclear Medicine Associations to be incorporated in the routine work-up of DAT-SPECT. Besides these observer dependent approaches, fully automated image-analysis techniques have been validated in the clinical setting. Their potential as tools to improve the diagnostic accuracy in patients presenting with parkinsonian features is reviewed here.

Diagnostic Accuracy of Combined FP-CIT, IBZM, and MIBG Scintigraphy in the Differential Diagnosis of Degenerative Parkinsonism: A Multidimensional Statistical Approach

“…However this voxel-based analysis technique, unlike ROI-based methods, has not yet been validated in routine clinical use and is therefore not generally recommended (4). Moreover, the results probably cannot be transferred to FP-CIT SPECT, because, compared with b-CIT, FP-CIT has a much higher affinity to the DAT and a much lower affinity to serotonin transporters, the latter being mainly responsible for accumulation of b-CIT in pons and mid brain.…”

“…In addition, different nonmotor symptoms may develop such as urinary or sleep disturbances (1). Although the diagnosis of PD can be unequivocal in patients with typical clinical symptoms, differentiation from atypical parkinsonian disorder (APD), such as parkinsonian type of multiple-system atrophy (MSA-P) and progressive supranuclear palsy (PSP), may be challenging in other cases (3)(4)(5). Because prognosis and treatment of patients with APD differ from those of PD patients (5), appropriate nosologic classification is warranted.…”

“…SPECT of the nigrostriatal dopaminergic system and of the sympathetic innervation of the heart is widely used in this context (4,9). For example, imaging of dopamine transporter (DAT) binding with 123 I-N-v-fluoropropyl2b-carbomethoxy-3b-(4-iodophenyl)nortropan (FP-CIT) successfully visualizes presynaptic dopaminergic degeneration of the nigrostriatal tract.…”

“…For example, imaging of dopamine transporter (DAT) binding with 123 I-N-v-fluoropropyl2b-carbomethoxy-3b-(4-iodophenyl)nortropan (FP-CIT) successfully visualizes presynaptic dopaminergic degeneration of the nigrostriatal tract. This procedure allows differentiation of degenerative parkinsonism from movement disorders that are not associated with dopaminergic deficit, such as essential tremor (4,5,10). DAT imaging alone, however, does not differentiate the various types of degenerative parkinsonism (PD vs. APD) with sufficient accuracy (5,11).…”

Validation of an automated morphological MRI-based 123I-FP-CIT SPECT evaluation method

“…However, visual classification is subjective and may be strongly dependent on the observer's experience [4]. In addition to visual interpretation, binding quantification based on manual delineation of striatal regions of interest (ROIs) is also readily available.…”