Magnetic Resonance Imaging of the Temporal Lobe: Normal Anatomy and Diseases  Alla Khashper, MD, Jeffrey Chankowsky, MD, FRCPC, Raquel del Carpio-O'Donovan, MD, FRCPC  Canadian Association of Radiologists Journal  Volume 65, Issue 2, Pages 148-157 (May 2014) DOI: 10.1016/j.carj.2013.05.001 Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 1 Imaging anatomy of temporal lobe. The temporal lobe is delimited from the frontal (FL) and parietal lobes (PL) by the sylvian fissure (SF). The posterior border is delimited from the occipital lobe (OL) by the imaginary temporo-occipital line (white line). Superior (S), medial (M), and inferior (I) temporal gyri are divided by corresponding superior and inferior sulci. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 2 Imaging anatomy of temporal lobe. Coronal T2-weighted (A) and sagittal T1 3-dimensional inversion recovery (B) images, showing mesial temporal lobe structures: sylvian fissure (1); superior (2), medial (3), inferior (4) temporal gyri; parahippocampal gyrus (5); collateral white matter (6); uncus (U); amygdala (A); and head (H), body (B), and tail (T) of the hippocampus. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 3 Axial fluid attenuated inversion recovery image of patient with Dandy-Walker spectrum, revealing enlargement of IV ventricle (*) and agenesis of the cerebellar vermis in association with globular-shaped unfolded hippocampi (arrows). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 4 Heterotopic grey matter in an 18-year-old patient with seizures. Coronal 3-dimensional T1 fast spoiled gradient-echo replaced image, revealing a large heterotopic focus (arrows) in the right temporal lobe. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 5 Coronal T2-weighted image, showing occult subtemporal meningoencephalocele (arrows) projecting into the sphenoid sinus medially from the inferomedial aspect of the right temporal lobe, which contains dysplastic brain parenchyma. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 6 A coronal T2-weighted magnetic resonance imaging, revealing age-related findings, including generalized volume loss, uniform dilatation of lateral ventricles, and hyperintense signal in the periventricular white matter. Hippocampi (arrows) are unremarkable. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 7 Coronal T2-weighted image, revealing bilateral marked mesial temporal encephalomalacia compatible with sequelae of herpes encephalitis. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 8 Coronal T1-weighted magnetic resonance imaging, demonstrating typical findings of symmetric bilateral mesial temporal atrophy in a patient with known Alzheimer disease, including increased width of the temporal horns and decreased height of the hippocampi (arrowheads). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 9 Right mesial temporal sclerosis on coronal oblique T2-weighted magnetic resonance imaging. Classic volume loss and dysmorphic morphology of the right hippocampus, hyperintense signal abnormality (dashed arrow), and associated secondary enlargement of the right temporal horn (arrow). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 10 Coronal oblique T2-weighted magnetic resonance imaging, showing secondary signs of mesial temporal sclerosis, including ipsilateral atrophy of fornix (arrow), mammillary body atrophy (arrowhead), temporal horn dilatation (dashed arrow), thinning of the collateral white matter (CWM) adjacent to the collateral sulcus (CS). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 11 Coronal oblique fluid attenuated inversion recovery magnetic resonance imaging, showing remote right selective transcortical amygdalohippocampectomy (*). Residual right hippocampus (arrow) is atrophic and shows hyperintense signal compatible with sclerosis, potentially explaining persistent refractory seizures. The minor gliosis is seen along surgical tract. Note atrophy of the right fornix (arrowhead). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 12 Cerebral autosomal dominant arteriopathy with subcortical infarctions and leukoencephalopathy (CADASIL) in a 38-year-old patient. Axial fluid attenuated inversion recovery (A) and T2-weighted (B) images, showing characteristic subcortical infarctions in the anterior temporal poles (A, arrows) and chronic ischemic changes in the basal ganglia and external capsules bilaterally. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 13 Coronal oblique T2-weighted magnetic resonance imaging, revealing small hyperintense hippocampi (arrows) and dilated temporal horns (arrowheads), which represent bilateral mesial temporal sclerosis. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 14 Limbic encephalitis in a 72-year-old patient who presented with memory impairment. Axial T2-weighted images, showing increased signal in both mesial temporal lobes (arrows). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 15 Herpes simplex virus encephalitis in a 56-year-old man with somnolence. Axial fluid attenuated inversion recovery image, revealing hyperintense signal (arrows) in the anterior and mesial portions of the right temporal lobe and along the gyrus rectus. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 16 Acute infarction in a 55-year-old patient with acute onset of expressive aphasia. Axial fluid attenuated inversion recovery image, demonstrating a hyperintense signal in the right temporal lobe, which involves both white and grey matter, much more typical of infarction rather than herpes simplex virus infection. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 17 Temporal lobe radiation necrosis 6 years after radiotherapy for nasopharyngeal carcinoma. Axial T2 image, showing signal abnormality in both inferior temporal lobes, right (arrow) greater than left. Sphenoid sinus mucosal thickening and right mastoid opacification reflect postradiation changes. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 18 Subtle postictal changes a few hours after generalized seizure. Symmetric mild bilateral hyperintense T2 signal abnormality (arrows) is seen in the hippocampi. The findings resolved on follow-up examination. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 19 Small low-grade astrocytoma in the right hippocampus (arrow) with an ill-defined increased T2-weighted signal, which remained stable over 10 years. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 20 Dysembryoplastic neuroepithelial tumour in a 21-year-old patient. T2-weighted image, revealing multicystic partially solid lesion (arrow) in the left hippocampus, which involves the cortex, without oedema or enhancement (not shown). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 21 T2-weighted image (A), showing a right temporal glioblastoma multiforme surrounded by marked oedema and infiltrative tumour (A, arrows), which causes significant mass effect. The lesion demonstrates aggressive imaging features, including signal heterogeneity, ill-defined borders, necrotic centre, and peripheral enhancement on T1-weighted sequence (B, arrowheads). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 22 Solitary brain metastases in a 68-year-old woman with breast cancer. A small left inferior temporal lesion surrounded by significant vasogenic oedema (A) and showing peripheral enhancement on T1-weighted postcontrast image (B, arrow). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 23 Toxoplasma abscess in a 57-year-old man known for having human immunodeficiency virus. Axial T2-weighted image, revealing a cortico-subcortical lesion (arrow) in the right posterior temporal lobe surrounded by marked oedema. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 24 Cavernoma in the left temporal lobe (arrow). Magnetic resonance imaging, showing a “salt and pepper” bright T2-weighted signal (due to slow-flowing blood and thrombosed vascular channels) surrounded by a rim of signal loss (due to hemosiderin deposition). Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 25 A 35-year-old patient with a 5-cm arteriovenous malformation in the right temporal lobe; the central structure is compatible with nidus (*), supplied by right middle cerebral artery branches (arrow) and drainage into superficial and deep venous systems. Canadian Association of Radiologists Journal 2014 65, 148-157DOI: (10.1016/j.carj.2013.05.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions