Bringing psychiatrists into the picture: Automated measurement of regional MRI brain volume in patients with suspected dementia

OBJECTIVE

The volumes of various brain regions can be rapidly quantified using automated magnetic resonance imaging tools. While these appear to be useful at face value, their formal clinical utility is not yet understood, particularly for non-neuroradiologists and in patients presenting with suspected dementia. This study investigated the utility of an automated normative morphometry tool on determinations of brain atrophy by psychiatrists and radiologists in a tertiary hospital.

METHODS

Consecutive magnetic resonance scans (n = 110) of patients referred with suspected neurodegenerative disorders were obtained retrospectively and rated by two neuroradiologists, two general radiologists and four psychiatrists over two sessions. First, conventional magnetic resonance sequences were shown. Then, morphometry colour-coded maps, which segmented T1-weighted magnetisation prepared rapid gradient echo images into brain regions and visualised these regions in colour according to their volumetric standard deviation from a normative population, were added to the second reading which occurred ⩾6 weeks later. Presence and laterality of atrophy in frontal, parietal and temporal lobes and hippocampal regions were measured using a digital checklist. The primary outcome of inter-rater agreement on atrophy was measured with Fleiss' Kappa (κ). We also evaluated the accuracy of the atrophy ratings for differentiating post hoc diagnosis of subjective cognitive impairment, mild cognitive impairment and dementia.

RESULTS

Agreement among all raters was fair in frontal lobe and moderate in other regions with conventional method (κ = 0.362-0.555). With morphometry, higher agreement was seen in all regions (κ = 0.551-0.654), reaching significant improvement in the frontal and temporal lobes. No significant improvement was seen within the various disciplines, except in frontal lobes rated by psychiatrists. Accuracy of atrophy ratings on determining post hoc diagnosis was significantly improved for distinguishing subjective cognitive impairment versus dementia.

CONCLUSION

In routine clinical assessment, automated normative morphometry complements the determination of regional atrophy and improves inter-rater agreement regardless of neuroradiology experience.

"Mind, body, and water!" - Postherpetic polydipsia masquerading as obsessive-compulsive disorder

Polydipsia has always been an intriguing entity in clinical psychiatry, since long. Other than being commonly associated with patients of chronic schizophrenia, as described in past, it can also mimic and present in other psychiatric disorders; and thus may be elusive for diagnosis and treatment. Here we describe a patient having polydipsia with prominent obsessive compulsive symptoms, which, after detailed investigations, was found to be secondary to herpes encephalitis. The organic nature of the illness was ascertained by distinct signal changes in right uncus, hippocampus and cingulate cortex; whereas conventional workup for polydipsia ruled out both central and nephrogenic diabetes insipidus. Treatment with fluoxetine, proper behavioural management and psychoeducation resulted in slow but sustained improvement in this patient. We then deconstruct the clinical manifestations and discuss the neurobiological explanation.