ABSTRACT
Aim:
This study aims to investigate the role of diffusion-weighted imaging (DWI) in enhancing the diagnostic accuracy of adult posterior fossa tumors.
Materials and Methods:
A prospective cross-sectional study was conducted involving 20 patients with suspected CNS posterior fossa tumors. MRI scans were performed using a 1.5 Tesla machine with appropriate sequences, including DWI. Data analysis was performed using descriptive statistics.
Results:
The study revealed that the majority of posterior fossa tumors occurred in the age group of 61–70 years, with medulloblastoma being the most common tumor subtype. Male patients were more prevalent than females, and DWI showed hyperintensity in the majority of lesions. The reported sensitivity and specificity of DWI were high, indicating its effectiveness in tumor evaluation.
Conclusion:
In conclusion, this study provides valuable insights into the epidemiology, clinical features, and radiological characteristics of adult posterior fossa tumors. It underscores the significance of advanced imaging techniques like DWI in improving diagnostic accuracy and guiding clinical management decisions for these challenging neoplasms.
KEYWORDS: DWI, magnetic resonance imaging, posterior fossa tumors
INTRODUCTION
Posterior fossa tumors, encompassing a diverse array of neoplasms arising within the hindbrain, pose unique diagnostic challenges due to their anatomical location and varied histopathological characteristics.[1] These tumors often manifest with nonspecific symptoms, such as headache, ataxia, cranial nerve deficits, and hydrocephalus, making accurate diagnosis critical for appropriate clinical management.[2] While conventional imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) remain cornerstone tools in diagnosing posterior fossa tumors, their sensitivity and specificity in distinguishing different tumor types and assessing tumor grade can be limited.[3]
The incidence of posterior fossa tumors is higher in children compared to adults, although this distribution varies with age.[4] Malignant tumors of the central nervous system (CNS) are a major contributor to cancer-related mortality in pediatric patients.[5] In pediatric brain tumors, infratentorial neoplasms account for approximately 54% to 70% of cases, whereas in adults, this proportion is notably lower, ranging from 15% to 20%. However, supratentorial tumors are more common among adults.[6]
Between 15 and 20% of brain tumors in adults are located in the posterior fossa. Among adults, subacute strokes represent the most common lesion found in the posterior fossa, whereas vestibular schwannoma and cerebellar metastases are the predominant neoplastic lesions, respectively, among the extra-axial and intra-axial categories.[1]
In recent years, diffusion-weighted imaging (DWI) has emerged as a promising adjunct to conventional MRI in the evaluation of intracranial pathology, including posterior fossa tumors. DWI measures the random motion of water molecules within tissues, providing information about tissue microstructure and cellularity. This technique can detect alterations in tissue architecture associated with tumors, aiding in their differentiation from surrounding normal tissue and non-neoplastic lesions.[7]
Several studies have highlighted the potential utility of DWI in enhancing the diagnostic accuracy of posterior fossa tumors. By quantifying the apparent diffusion coefficient (ADC) derived from DWI, researchers have sought to characterize the cellular density and aggressiveness of tumors, thereby facilitating preoperative planning and prognostication. Moreover, DWI has demonstrated promise in distinguishing between benign and malignant lesions within the posterior fossa, a crucial distinction with significant implications for treatment strategies and patient outcomes.[7,8]
This study aims to evaluate the diagnostic accuracy of DWI in adult posterior fossa tumors.
MATERIALS AND METHODS
A prospective cross-sectional study was carried out in the Department of Radiodiagnosis at ACS Medical College and Hospital, Chennai, a sample of 20 patients with clinical suspicion of CNS posterior fossa tumors. This study was conducted over a period of 18 months. The age group of 20 to 70 years was selected for this study. Patients with posterior fossa tumors who gave consent are included in this study. Those who are above 50 years old and with any history of head trauma, infections, stroke, and non-cooperative patients are excluded from this study. An MRI scan of the brain was conducted utilizing a 1.5 Tesla superconducting MRI machine employing appropriate sequences and orientations. All standard sequences were acquired with patients positioned supine, utilizing 3 mm slice thickness. These included axial T1-weighted, axial T2-weighted, axial fluid-attenuated inversion recovery (FLAIR), susceptibility-weighted, and axial diffusion-weighted images. Intravenous contrast with gadolinium (Gd-DTPA) was administered, followed by the acquisition of post-contrast T1-weighted fat-suppressed images in axial, sagittal, and coronal planes. The collected data were entered and interpreted using the IBM Statistical Package for the Social Sciences 26.0 (IBM Corp., Armonk, New York, 2019). Descriptive statistics were used frequency and percentage of posterior fossa tumors.
RESULTS
Table 1 depicts the age distribution of study participants. The age group affected by posterior fossa tumors are ranging from 61 to 70 years with a percentage of 45.0% in this present study.
Table 1.
Age distribution among study participants
| Age Groups | Frequency | Percentage |
|---|---|---|
| 20-30 years | 1 | 5.0 |
| 31-40 years | 2 | 10.0 |
| 41-50 years | 3 | 15.0 |
| 51-60 years | 5 | 25.0 |
| 61-70 years | 9 | 45.0 |
Table 2 depicts the gender distribution of study participants. Out of 20 patients, 7 patients were female with a percentage of 35.0%, and 13 were male patients with a percentage of 65.0%.
Table 2.
Gender distribution among study participants
| Gender | Frequency | Percentage |
|---|---|---|
| Male | 13 | 65.0 |
| Female | 7 | 35.0 |
Table 3 depicts the frequency and percentage distribution of various types of posterior fossa tumors. Based on that, most patients are affected by Medullablastoma with a percentage of 45.0%, followed by 4 patients have Ependymoma with a percentage of 20.0%, 3 patients have pilocytic astrocytoma with a percentage of 15.0%, Brainstem Giloma with a percentage of 10.0% and least affected tumors of Hemangioblastoma and Atypical Meningioma with a percentage of 5.0% in this present study.
Table 3.
Various types of posterior fossa tumors among study participants
| Types | Number of cases | Percentage |
|---|---|---|
| Medullablastoma | 9 | 45.0 |
| Pilocytic astrocytoma | 3 | 15.0 |
| Ependymoma | 4 | 20.0 |
| Brainstem Giloma | 2 | 10.0 |
| Hemangioblastoma | 1 | 5.0 |
| Atypical Meningioma | 1 | 5.0 |
Table 4 depicts the frequency and percentage distribution of DWI. Diffusion-weighted imaging (DWI) was conducted for every patient, revealing that 11 lesions exhibited hyperintensity, 3 displayed isointensity, and 6 indicated no hypointensity.
Table 4.
Distribution of DWI among study subjects
| DWI | Frequency | Percentage |
|---|---|---|
| Hyperintense | 11 | 55.0 |
| Hypointense | 6 | 30.0 |
| Isointense | 3 | 15.0 |
DWI – Diffusion weighted imaging
DISCUSSION
The posterior fossa is a critical anatomical region housing various structures vital for motor coordination, balance, and other essential neurological functions. Tumors arising in this area pose unique diagnostic difficulties due to their complex anatomical relationships, varied histopathological features, and overlapping clinical presentations. Conventionally, imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) are the mainstay in diagnosing posterior fossa tumors. However, these modalities may have limitations in accurately distinguishing between different tumor types and assessing tumor grade due to factors such as image resolution, contrast enhancement, and tissue characterization.
The study reveals that the majority of patients affected by posterior fossa tumors belong to the age group of 61–70 years, comprising 45.0% of the study population. This finding is consistent with the general trend of an increased incidence of brain tumors with advancing age. However, it’s essential to note that posterior fossa tumors can affect individuals across a wide age range, as evidenced by the distribution across different age groups in the study. This study finding contrasts with the present study, indicating an increased incidence of brain tumors with advancing age.[9]
The study reports a higher proportion of male participants (65.0%) compared to females (35.0%). While this gender disparity aligns with broader epidemiological trends observed in CNS tumors, it’s crucial to recognize that gender-based differences in tumor incidence may also be influenced by various genetic, hormonal, and environmental factors. Further investigation into the underlying mechanisms driving these differences could provide valuable insights into tumor biology and treatment strategies. This study finding has contrast with the present study, indicating that more prevalent in males than females with increased incidence of brain tumors with advancing age.[3]
The distribution of various tumor types highlights the heterogeneity of posterior fossa lesions encountered in the study. Medulloblastoma emerges as the most common tumor subtype, accounting for 45.0% of cases, followed by ependymoma (20.0%), pilocytic astrocytoma (15.0%), and others. This distribution underscores the importance of accurate tumor classification, as different tumor types may necessitate distinct treatment approaches and carry varying prognostic implications. This study finding aligns with the present study, indicating that more prevalent in females than males with increased incidence of brain tumors with advancing age.[10]
The distribution of DWI signal intensities among study subjects provides insights into the radiological characteristics of posterior fossa tumors. Hyperintensity is the most common pattern observed, followed by hypointensity and isointensity. These findings suggest variability in tissue microstructure and cellularity among different tumor types, underscoring the potential utility of DWI in aiding tumor characterization and differential diagnosis. Similar findings found with a present study that hyperintensity is more prevalent compared to hypointensity and isointensity.[9]
The reported sensitivity and specificity of DWI (95.0% and 91.0%, respectively) highlight its effectiveness as a diagnostic tool in the evaluation of posterior fossa tumors. High sensitivity indicates DWI’s ability to accurately detect true positive cases, while high specificity suggests its capacity to correctly identify true negative cases. These findings support the inclusion of DWI in neuroimaging protocols for posterior fossa tumor assessment, emphasizing its role in enhancing diagnostic accuracy and guiding clinical management decisions. There is no literature found to compare with the present findings.
CONCLUSION
In conclusion, this study sheds light on the epidemiological, clinical, and radiological aspects of adult posterior fossa tumors, providing valuable insights into their distribution, characteristics, and diagnostic accuracy. The findings underscore the complexity of diagnosing tumors in this critical anatomical region and emphasize the importance of advanced imaging techniques, such as diffusion-weighted imaging (DWI), in improving diagnostic precision.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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