European Journal of Cardiovascular Medicine

A diagnostic challenge existed for clinicians until the previous century because the skull was sealed. The imaging of the CNS (Central Nervous System) has undergone remarkable changes in the past century. Magnetic resonance imaging's developments have affected all aspects of neuroscience practice overall and the treatment of intra-axial brain lesions specifically. One common type of neuroimaging abnormality is a “ring-enhancing lesion." These are lesions that appear as central non-enhancing areas with a bright peripheral rim of enhancement on MRI or CT images after contrast dye is applied.[1] Cross sectional imaging modalities are the first to detect the symptoms of an intracranial space-occupying lesion in a patient who comes to the hospital. It can be caused by various etiologies, such as brain abscesses, tuberculoma, cystic metastasis, primary brain tumors, infarcts, and lymphomatous tumors. Most of the lesions are located at the interface between gray and white matter and subcortical areas. The main reason for multiple ring-enhancing lesions in the brain in India is infectious diseases. Tuberculosis is the most common infection, followed by neurocysticercosis. Some non-infectious diseases that can cause these lesions are neoplastic disorders. The majority of neoplastic brain lesions are secondary to a systemic neoplastic illness.[2] For intracranial abscesses, medical management strategies are antibiotics or drainage, and for neoplasms, they are surgery and biopsy. This poses a serious neurosurgical challenge that requires us to diagnose correctly.[1] MRI can find more than 90% of brain lesions of different kinds, while CT only finds 77%. MRI is safer and less invasive than CT since it does not need iodine-based contrast agents or X-rays that cause radiation. This makes MRIs better for children and older people.[2] But conventional MRI is less accurate, with only about 61.4% sensitivity in detecting neoplasms from abscesses. So, we use advanced imaging methods like the diffusion-weighted method that detects restriction and spectroscopy that identifies metabolites as an extra aid for better diagnosis.[3] Diffusion imaging is an advanced technique of imaging that measures the movement of water molecules in tissues and can detect vascular territory infarcts, tumors, epilepsy, and white matter disorders by calculating the apparent diffusion coefficient value. Magnetic resonance spectroscopy can also characterize the lesion by measuring the altered levels of metabolites.[4] These noninvasive investigations help us avoid needless intervention, provide a quick and precise diagnosis, and improve the patient’s outcome.[5] The latest advances in MRI include ultra-fast scanners and contrast agents that are sensitive to metabolic changes. For MRS imaging, 3 Tesla scanners are the standard. However, using 4 Tesla or 4.7 Tesla scanners can improve our diagnosis, as they have higher sensitivity than 3 Tesla due to their stronger field strength. To overcome the limitations of gradient performance, 7 Tesla scanners are being developed. With hyperpolarized MRI and metabolic contrast, we can map the rates of enzymatic reactions. This will have a significant impact on the future of MR spectroscopy and its technical development. Consequently, various research studies will be possible with these emerging techniques of MRS. [6]

Aims and Objectives

• To assess the usefulness of diffusion-weighted imaging and magnetic resonance spectroscopy in diagnosing intracranial peripherally enhancing lesions.
• To study characteristic imaging findings of various ring-enhancing lesions by MRI sequences with contrast.
• To differentiate ring-enhancing brain lesions using DWI (Diffusion-Weighted Imaging) and ADC (Apparent Diffusion Coefficient) values.
• To study the role of MR spectroscopy in the evaluation of various ring-enhancing lesions.
• To analyze the efficacy of MRI in adjunct with DWI and MRS in correctly diagnosing the ring-enhancing lesions with histopathological correlation or follow up wherever possible

This was a hospital-based observational prospective study conducted among 68 patients with the diagnosis of cerebral ring enhancing lesions at the Department of Radiodiagnosis at Shri B.M. Patil Medical College, Hospital and Research Centre, BLDE (DU), situated at Vijayapura, Karnataka, from September 2022 to April 2024, after obtaining clearance from the institutional ethics committee and written informed consent from the study participants.

Inclusion Criteria

• Patients with intracranial ring enhancing lesions, which are detected on contrast MR studies and are taken up prospectively.
• Patients of all age groups [both males and females].

Exclusion Criteria

• Patients having contraindications to intravenous contrast agents.
• Patient having history of fear of closed spaces [claustrophobia].
• Patient with a prior history of any metallic implants inside the body or any pacemakers in situ.

Statistical Methods

Data was entered in a Microsoft Excel data sheet, and analysis was done using SPSS 22.0 version software. Mean ± SD [Min-Max] was calculated for results. The results of the cases were presented in number [percentage]. Descriptive statistics, frequencies, and proportions were calculated and tabulated. Sensitivity, specificity, negative predictive value, and positive predictive value were calculated using SPSS software. MR spectroscopy with DWI values and their diagnostic accuracy were also determined. The Chi square test, Fisher exact test, and one sample student’s t-test were the tests of significance for categorical data. A p-value <0.05 was considered statistically significant.

In the study, NAA was decreased in 50% of patients with metastasis, neurocysticercosis, 71% of patients with primary brain tumors, and 52.6% of patients with tuberculoma, and increased in 50% of patients with cerebral abscess. There was a significant difference in NAA change with respect to diagnosis.

Cho was increased in 50% of patients with cerebral abscess and metastasis, in 100% of patients with neurocysticercosis and primary brain tumors, and in 78.9% of patients with tuberculomas. There was a significant difference in Cho with respect to the diagnosis.

Similarly, lip-lac was increased in 100% of patients with cerebral abscess and tuberculoma, 30% of patients with metastasis and primary brain tumors, and 50% of patients with neurocysticercosis. There was a significant difference in lip-lac change with respect to diagnosis.

Creatine was decreased in 12.9% of subjects with primary brain tumors and 10.5% of patients with tuberculoma. There was a significant difference in creatine change with respect to diagnosis.

The mean Cho/Cr ratio was high in primary brain tumors [4.3 ± 0.36], followed by metastasis and tuberculoma.

The mean Cho/NAA ratio was high in primary brain tumors [1.7 ± 1.3], followed by tuberculoma and metastasis.

The mean NAA/Cho ratio was high in cerebral abscess [1.65± 0.06] and low in primary tumors.

The mean NAA/Cr ratio was high in cerebral abscess [2.2± 0.06], followed by metastasis.

There was a significant difference in the mean Cho/Cr, Cho/NAA ratio, NAA/Cho, and NAA/Cr with respect to diagnosis.