MTA index: a simple 2D-method for assessing atrophy of the medial temporal lobe using clinically available neuroimaging.
OBJECTIVE
Despite a strong correlation to severity of AD pathology, the measurement of medial temporal lobe atrophy (MTA) is not being widely used in daily clinical practice as a criterion in the diagnosis of prodromal and probable AD. This is mainly because the methods available to date are sophisticated and difficult to implement for routine use in most hospitals-volumetric methods-or lack objectivity-visual rating scales. In this pilot study we aim to describe a new, simple and objective method for measuring the rate of MTA in relation to the global atrophy using clinically available neuroimaging and describe the rationale behind this method.


METHODS
This method consists of calculating a ratio with the area of 3 regions traced manually on one single coronal MRI slide at the level of the interpeduncular fossa: (1) the medial temporal lobe (MTL) region (A); (2) the parenchima within the medial temporal region, that includes the hippocampus and the parahippocampal gyrus-the fimbria taenia and plexus choroideus are excluded-(B); and (3) the body of the ipsilateral lateral ventricle (C). Therefrom we can compute the ratio "Medial Temporal Atrophy index" at both sides as follows: MTAi = (A - B)× 10/C.


CONCLUSIONS
The MTAi is a simple 2D-method for measuring the relative extent of atrophy in the MTL in relation to the global brain atrophy. This method can be useful for a more accurate diagnosis of AD in routine clinical practice. Further studies are needed to assess the usefulness of MTAi in the diagnosis of early AD, in tracking the progression of AD and in the differential diagnosis of AD with other dementias.
Unidad de Neurología, Hospital Álvarez-Buylla Mieres, Spain ; Departamento de Morfología y Biología Celular, Universidad de Oviedo Oviedo, Spain ; Instituto de Neurociencias, Universidad de Oviedo Oviedo, Spain.
Manuel
M
Menéndez-González
Departamento de Morfología y Biología Celular, Universidad de Oviedo Oviedo, Spain ; Instituto de Neurociencias, Universidad de Oviedo Oviedo, Spain.
Alfonso
A
López-Muñiz
Departamento de Morfología y Biología Celular, Universidad de Oviedo Oviedo, Spain.
José A
JA
Vega
Instituto de Investigación Científica, Universidad Juárez del Estado de Durango Durango, México.
José M
JM
Salas-Pacheco
Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González/UNAM México DF, Mexico ; Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Ajusco Medio México DF, Mexico.
Oscar
O
Arias-Carrión
Alzheimer; MRI; biomarker; diagnosis; medial temporal lobe atrophy; mild cognitive impairment; neuroimaging