Patients with neurologic complaints are often referred for an MR exam, where different sequences can detect a wide variety of brain and blood vessel abnormalities and visualize differences between tissues that may be unclear on other modalities. In neuroimaging, Cube, SWAN and BRAVO provide excellent whole-brain coverage, including the orbits.
Papilledema is characterized by swelling of the optic nerve and intercranial pressure. This swelling is a reaction to a build-up of pressure in or around the brain, with many possible causes, such as a brain tumor or hemorrhage1.
Central neurocytoma is a supratentorial and often calcified brain tumor affecting young adults, typically located in the lateral ventricles in the region of the foramen of Monro. Clinically, the tumor leads to increased intracranial pressure and visual and mental disturbances2.
Cube is enabled for T1 FLAIR, T2, T2 FLAIR, and PD sequences and can replace several 2D slice acquisitions with one single 3D volume scan. Sub-millimeter isotropic volumetric Cube data can be easily reformatted into any plane without gaps, and with the same resolution as the native plane. Cube provides ultra-thin slices with good SNR to help visualize small and subtle lesions without partial volume averaging effects. ARC helps to speed up the sequence while minimizing artifacts and still providing high tissue contrast.
Susceptibility Weighted ANgiography (SWAN) allows for the clear depiction of microbleeds, providing an improvement over previous gradient sequences. It can help in diagnosing neurological disorders and pathology. BRAin VOlume (BRAVO) is a fast and high-resolution 3D acquisition that delivers an excellent T1 contrast between gray and white matter.
Patient history
A 33-year-old female with a history of double vision, headaches and esophoria. She presented with normal eyesight results but had severe papilledema that can be caused by intracranial pressure. Patient was referred for a brain MR including the orbits.
Technique
The MR study demonstrates the presence of a large tumor in the left lateral ventricle that appears to be centered on the foramen of Monro. There are multiple flow voids noted in relation to the tumor mass, which demonstrates diffusion restriction with a positive ADC map (DWI).
On the SWAN sequences there is also signal dropout that appears to be related to calcifications. The lesion results in partial obstructive hydrocephalus on the left with dilatation of the left lateral ventricle.
Figure 1.
(A-C) Axial T2* 3D SWAN, 1.0 x 1.2 x 3.8 mm; (B) filtered phase showing signal dropout and appearance of calcifications in the tumor; and (C) image depicts extension of tumor with midline shift of central structures.
Figure 2.
(A) Axial DWI b1000, 1.9 x 1.9 x 5 mm and (B) positive ADC map showing multiple flow voids and diffusion restriction.
Figure 3.
(A-C) Axial T1 BRAVO with contrast, 1.1 x 1.25 x 1.4 mm; (B, C) demonstrate heterogenous enhancement.
There is also a small amount of periventricular deep white matter edema in the left centrum semiovale where the tumor mass extends up to the ventricular wall without clear distinction between the tumor and the ventricular wall. There is also no clear interface between the portion of the tumor and the body of the corpus callosum, which is thin over the mid to posterior aspect.
The tumor measures 4.1 x 5.2 x 5.5 cm and demonstrates heterogenous enhancement on the post-contrast imaging with BRAVO. At the level of the septum pellucidum there is significant extension of the tumor across the midline with associated midline shift of the central structures to the right by approximately 4.8 mm. Although there is inferior mass effect, there is no sign of any herniation through the tentorium. Due to the central mass effect, there is compression over the proximal aspect of the aqueduct.
The large tumor present in the left lateral ventricle as described is resulting in obstruction and mild dilatation of the ventricles, especially the left lateral ventricle due to compression at the foramen of Monro, as well as compression of the third ventricle and the proximal aspect of the aqueduct. A main consideration is a central neurocytoma with features not typical of choroid plexus papilloma, intraventricular meningioma or ependymoma.
There were no abnormalities in the orbital contents.
Discussion
Central neurocytoma is a rare intraventricular tumor of neuronal differentiation with fairly characteristic imaging features, appearing as heterogenous mass of variable size and demonstrating enhancement within the lateral ventricle, typically attached to the septum pellucidum. It is typically seen in young patients and generally has a good prognosis provided a complete resection is achieved.
The primary therapeutic option for neurocytoma tumors is the complete surgical resection that markedly diminishes the chance of recurrence; it also relieves intracranial pressure developed by the tumor and restores cerebrospinal fluid channels.
Although the role of radiotherapy to the tumor bed after surgical resection has been debated, it has nevertheless been implemented in many cases with the aim of preventing tumor progression and recurrence, particularly in patients with incomplete resection.
Stereotactic radiosurgery has emerged as a potential treatment tool in the management of neurocytomas, due to rapid dose fall off and shorter treatment time, as compared to conventional radiotherapy. However, further studies with long-term follow up are required as recurrences typically occur later in life. Chemotherapy appears to have a limited role in the management of neurocytomas.
MR is helpful to refine the differential diagnosis of these patients and contributes to preoperative diagnosis and planning.
References
- Schirmer CM, Hedges TR 3rd. Mechanisms of visual loss in papilledema. Neurosurg Focus. 2007;23(5):E5. doi: 10.3171/FOC-07/11/E5. PMID: 18004967.
- Hassoun J, Söylemezoglu F, Gambarelli D, et al. Central neurocytoma: a synopsis of clinical and histological features. Brain Pathol. 1993 Jul;3(3):297-306. doi: 10.1111/j.1750-3639.1993.tb00756.x. PMID: 8293189.
