 Postoperative changes from previous left parietal occipital craniotomy are again seen, with a left occipital resection cavity with scattered peripheral hemosiderin deposition. The resection cavity is again filled with FLAIR hyperintense material. Overall, the cavity appears contracted compared to prior examination. There is redemonstration of peripheral enhancement surrounding the parieto-occipital cavity. The reference nodule located along the posterior aspect measures 9 mm, unchanged. Again, the enhancement is seen extending anteriorly to the posterior horn of the left lateral ventricle with involvement of the ependyma.There is extensive surrounding T2/FLAIR hyperintensity which extends slightly more anteriorly in the left frontal lobe. In addition, there is increased T2/FLAIR signal extending along the splenium of the corpus callosum across the midline. There is however decreased mass effect upon the posterior horn of the left lateral ventricle. There is no evidence for hydrocephalus, with interval slight increased size of right lateral ventricle likely back to baseline with resolved mass effect. The rightward midline shift has decreased slightly since prior examination now measuring 6 mm. New mild patchy diffusion restriction is now present anterior to the cavity and minimally involving the splenium of the corpus callosum. New foci of gradient susceptibility likely related to hemosiderin deposition is demonstrated along the superior aspect of the cavity. Scattered new areas of leptomeningeal enhancement are demonstrated, most prominent involving the posterior fossa and spinal cord. Several new enhancing nodular lesions are identified and likely related to carcinomatous spread through the subarachnoid space with parenchymal infiltration. For example, there are nodules involving the inferior aspects of the left frontal lobe, the pontomedullary junction, the cerebellar vermis, and the partially visualized cervical spinal cord. The largest nodule measures 8 x 8 mm located in the left frontal lobe (series 11, image 15). Majority of these nodules are associated with running T2/FLAIR hyperintensity, most prominent involving the brainstem. In addition, there is new enhancement within the bilateral internal auditory canals underlying post contrast images suggestive of additional leptomeningeal tumor involvement. No extra-axial fluid collection is identified. Normal flow-voids are demonstrated in the major intracranial vascular structures.
1. Overall, findings are concerning for leptomeningeal carcinomatosis with multiple new enhancing subarachnoid lesions identified in the inferior left frontal lobe, posterior fossa, and brainstem, and spinal cord. Some of these nodules appear to invade the adjacent parenchyma.2. There is slight retraction of the left parieto-occipital cavity with persistent peripheral enhancement extending anteriorly to the posterior horn of the left lateral ventricle with ependymal involvement. Overall there appears to be slightly increased T2/FLAIR signal extending anteriorly in the left frontal lobe as well as approximately corpus callosum although with decreased mass effect and midline shift.3. New enhancement involving the internal auditory canals is favored to relate to cranial nerve leptomeningeal involvement.4. Patchy mild diffusion restriction anterior to the resection cavity, as well as susceptibility likely related to hemosiderin deposition along the superior aspect of the cavity, may be related to treatment.