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Sheila N F Liberato de Matos1,2, Giovanna Ladeia-Rocha3, José Abraão Carneiro Neto1
1Immunology Service, Professor Edgard Santos University Hospital, Federal University of Bahia, Salvador.
Objective:
In the diagnosis of HTLV-1-associated myelopathy (HAM), while magnetic resonance imaging (MRI) is essential to exclude other diseases, its power is limited regarding HAM diagnosis, as only 30% of affected patients present with spinal cord atrophy. Diffusion tensor imaging (DTI) may enable the detection of damage in the white matter microstructure. Here, we quantitatively assess spinal cord damage using DTI and evaluate conventional MRI parameters of the spinal cord in HTLV-1-infected individuals.
Methods:
This cross-sectional study involved 33 HTLV-1 carriers, 28 patients with definite-HAM, and 11 seronegative healthy subjects (HS). Region-of-interest (ROI)-based fractional anisotropy (FA) and mean diffusivity (MD) measurements were performed in the upper thoracic and lumbar regions of the spinal cord. Thoracic index was defined as 1/ (anteroposterior diameter × transverse diameter) measured at the fifth 5th vertebral level. Receiver operating characteristic (ROC) curve analysis was used to determine optimal cutoff FA, MD, and thoracic index values.
Results:
Spinal cord atrophy was observed in 15 (53.6%) patients with definite-HAM. The area under the ROC curve in the thoracic spinal cord was 0.824 (95% CI, 0.716-0.932), 0.839 (95% CI: 0.736-0.942), and 0.838 (95% CI: 0.728-0.949) for FA, MD, and the thoracic index, respectively. Lower FA and higher MD values were observed in the definite-HAM group compared to HTLV-1 carriers and HS at the T5 vertebral level (p < 0.01).
Interpretation:
Complementary to conventional MRI, DTI analysis of the spinal cord and thoracic index determination can offer additional insight that may prove useful in the diagnosis of HAM.
Insights
Diffusion tensor imaging (DTI) and thoracic index measurements show promise for diagnosing Human T-lymphotropic virus type 1-associated myelopathy (HAM). These advanced techniques offer greater diagnostic insight than conventional MRI alone for HTLV-1 carriers and HAM patients.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diagnosis of Human T-lymphotropic virus type 1-associated myelopathy (HAM) relies on Magnetic Resonance Imaging (MRI) to exclude other conditions, but its sensitivity for HAM is limited, with spinal cord atrophy seen in only 30% of patients.
- Diffusion Tensor Imaging (DTI) offers potential for detecting microstructural white matter damage in the spinal cord, which may be crucial for early HAM diagnosis.
- Conventional MRI parameters have shown limited utility in definitively diagnosing HAM, necessitating the exploration of advanced imaging techniques.
Purpose of the Study:
- To quantitatively assess spinal cord damage in HTLV-1-infected individuals using DTI.
- To evaluate the utility of conventional MRI parameters alongside DTI in diagnosing HAM.
- To determine the diagnostic accuracy of DTI-derived metrics (Fractional Anisotropy - FA, Mean Diffusivity - MD) and the thoracic index in differentiating HAM patients.
Main Methods:
- A cross-sectional study included 33 HTLV-1 carriers, 28 patients with definite HAM, and 11 healthy subjects (HS).
- Region-of-interest (ROI)-based FA and MD measurements were performed in the thoracic and lumbar spinal cord.
- The thoracic index was calculated, and Receiver Operating Characteristic (ROC) curve analysis was used to determine optimal diagnostic cutoffs for FA, MD, and the thoracic index.
Main Results:
- Spinal cord atrophy was present in 53.6% of definite HAM patients.
- ROC analysis demonstrated high diagnostic accuracy for FA (0.824), MD (0.839), and thoracic index (0.838) in the thoracic spinal cord.
- Definite HAM patients exhibited significantly lower FA and higher MD values compared to HTLV-1 carriers and HS at the T5 vertebral level (p < 0.01).
Conclusions:
- DTI analysis of the spinal cord, specifically FA and MD metrics, provides valuable quantitative information about white matter integrity.
- The thoracic index, derived from conventional MRI, also shows significant diagnostic potential for HAM.
- Combined with conventional MRI, DTI and thoracic index determination offer complementary insights that can aid in the diagnosis of HAM.