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CC BY-NC-ND 4.0 · Indographics 2024; 03(02): 158-159
DOI: 10.1055/s-0044-1792120
Letter to the Editor

Response to “Reply to Imaging in Musculoskeletal Tuberculosis”

Stanzin Spalkit
1   Department of Radiodiagnosis and Interventional Radiology, All India Institute of Medical Sciences, New Delhi, India
,
Ankur Goyal 
1   Department of Radiodiagnosis and Interventional Radiology, All India Institute of Medical Sciences, New Delhi, India
,
Shivanand Gamanagatti
1   Department of Radiodiagnosis and Interventional Radiology, All India Institute of Medical Sciences, New Delhi, India
,
Devasenathipathy Kandasamy
1   Department of Radiodiagnosis and Interventional Radiology, All India Institute of Medical Sciences, New Delhi, India
,
Raju Sharma
1   Department of Radiodiagnosis and Interventional Radiology, All India Institute of Medical Sciences, New Delhi, India
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Funding None.
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We thank the authors for their comments on our article “Imaging in musculoskeletal tuberculosis.”[1]

Our review aimed to provide a comprehensive albeit concise resource for understanding musculoskeletal tuberculosis (TB), focusing on pathogenesis, diagnostic laboratory findings, characteristic imaging features, and an overview of management strategies. It was beyond the scope of the review to delve into the extremely rare manifestations of spinal TB (like the extramedullary intradural granuloma) or the specific classification of each peripheral joint involvement.

Multifocal osteoarticular TB represents an uncommon form of skeletal TB and is characterized by the involvement of two or more noncontiguous locations. When this occurs in the spine, it is referred to as “skip lesions,” as we described in our article. Its incidence is higher in regions with a high prevalence of TB and has been associated with human immunodeficiency virus (HIV) infection, multidrug-resistant TB (MDR-TB), or chronic disease progression. Joint involvement in such cases may suggest TB rather than metastases. Despite the multifocal nature of the disease, most cases reported in the literature also document the presence of associated abscess formation.[2]

The ivory vertebra sign is radiologically characterized by a smooth, ivory-like appearance of one or more vertebral bodies, which maintain their size and contours without altering the adjacent intervertebral disks. The primary differential diagnoses for this sign include metastatic cancer, Paget's disease, and lymphoma. While TB can lead to vertebral sclerosis during the healing phase, diffuse sclerosis of the vertebral body without associated intervertebral disk space loss or endplate irregularity is uncommon.[3]

Modic type 1 degenerative endplate changes can be differentiated from early infection based on the absence of T2 hyperintense disk signal, a normal band of marrow between abnormal vertebral T2 hyperintensity and the disk, and absence of pre-/paravertebral or epidural collections. In ambiguous cases, a diffusion “claw sign” may favor degenerative changes over infection.[4]

While fluorodeoxyglucose positron emission tomography (FDG-PET) can detect abnormal metabolic activity in active inflammation and multifocal involvement, it lacks specificity in distinguishing between infectious and noninfectious pathologies. Magnetic resonance imaging (MRI) remains the preferred modality for evaluating skeletal TB. PET can help assess therapeutic response when metallic implants limit MRI use and as a follow-up tool in multifocal TB.[5]

In pediatric patients, while the imaging findings for diagnosing TB are fundamentally similar to those seen in adults, it is essential to consider the normal developmental anatomy of children, particularly ossification centers, physes, and cartilage, to avoid misinterpretation of normal variants as pathological changes.[6]

To assess treatment response, we advocate the use of contrast-enhanced MRI (CE-MRI) at the completion of therapy, as it provides a more reliable indicator of disease resolution. Radiographs, while helpful, should not be solely relied upon for evaluating treatment outcomes. Sclerosis typically signifies healing after an initial osteolytic phase and should become visible within 5 months of treatment, with progression continuing over a year. Moreover, the recovery of vertebral body height is not considered a definitive criterion for treatment success, as it is contingent on the extent of the initial vertebral involvement.[7]

The classification of TB of the shoulder into dry type, fulminating type, and mobile type is completely based on clinical presentation and not radiological features. The Shanmugasundaram classification of TB of the hip is based on radiological morphology at presentation and does not actually denote the stage of the disease.[8]



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Artikel online veröffentlicht:
30. Dezember 2024

© 2024. Indographics. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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