Cortical motor neurone loss and corticospinal tract (CST) degeneration
are typical of amyotrophic lateral sclerosis (ALS), It is a matter of
debate whether qualitative assessment of the CST by MRI is useful in
the diagnosis. It is also an open question whether quantitative determ
ination of the T2 relaxation times can improve its value. Signal inten
sity along the CST on 14 consecutive slices was assessed using arbitra
ry visual rating on double-echo T2-weighted and proton-density spin-ec
ho images of 21 patients with ALS and 21 age-and sex-matched controls.
T2 was determined quantitatively. On the T2-weighted images the patie
nts' ratings did not differ from that of controls. The T2 of patients
and controls showed no statistical difference in any slice. There was
no correlation between T2 and patient age, duration of the disease, or
predominant bulbar, lower or upper motor neurone signs. The only corr
elation between MRI findings and disease was on the proton-density ima
ges: all cases in which the CST was poorly seen were controls; a clear
ly high signal CST was seen only in the patients. High conspicuity of
the CST was thus specific but not sensitive for the diagnosis of ALS.
T2-weighted images and measurement of T2 were not useful for diagnosis
.