Astrocytoma

a Astrocytoma grade 2

a Astrocytoma grade 2

Left Occipital Lobe Tumor

Fig. 11.16 a Noncontrast head CT (left) depicts a hypodense, well-demarcated lesion in the right temporal lobe. After contrast administration (right), the tumor, a grade 2 astrocytoma, remains unchanged. A subacute stroke could have a similar appearance. b In the T2-weighted sequence (left), edema is seen in the left occipital lobe. After contrast administration, the T1-weighted sequence (right) demonstrates small contrast-enhancing foci, compatible with but not specific for a malignant tumor. This is a grade 4 astrocytoma. Small abscesses, for example, in toxoplasmosis, may look similar.

b Astrocytoma grade 4

b Astrocytoma grade 4

Grade Astrocytoma

Fig. 11.16 a Noncontrast head CT (left) depicts a hypodense, well-demarcated lesion in the right temporal lobe. After contrast administration (right), the tumor, a grade 2 astrocytoma, remains unchanged. A subacute stroke could have a similar appearance. b In the T2-weighted sequence (left), edema is seen in the left occipital lobe. After contrast administration, the T1-weighted sequence (right) demonstrates small contrast-enhancing foci, compatible with but not specific for a malignant tumor. This is a grade 4 astrocytoma. Small abscesses, for example, in toxoplasmosis, may look similar.

Astrocytoma Brain Tumor Grade

always already spread along white-matter tracts into other parts of the brain, invisible to the radiologist or neurosurgeon.

f Preoperative imaging of brain tumors requires a complete i depiction of their configuration, size, and spatial relationship to important neighboring anatomical structures in three planes with contrast-enhanced T1-weighted sequences.

Hemangioblastoma: Hemangioblastomas occur in middle-aged adults and are preferentially located in the cerebellum. In 15% of cases they are associated with von Hippel-Lindau disease. The typical image appearance is that of a large cyst with a strongly contrast-enhancing mural nodule (Fig. 11.17).

Brain metastases: Brain metastases are multifocal in 70% of cases (Fig. 11.18). MRI is the most sensitive modality for detection of metastases (Fig. 11.19). Metastases are often characterized by extensive perilesional edema and strong contrast enhancement; lung and breast carcinomas are among the most common primary tumors to cause brain metastases.

I Hemangioblastoma

Multifocal Primary Lung Carcinoma
Fig. 11.17 This hemangioblastoma is located in the right cerebellar hemisphere. The T1-weighted sequence after contrast administration shows the typical appearance of a cyst with a peripheral enhancing nodule.

Brain Metastases

Brain Metastases

Fig. 11.18a This postcontrast CT image shows multiple metastases from a bronchial carcinoma. Now the radiation oncologists have to get to work. b The exterior CSF space is completely used up in this posterior fossa. A supratentorial obstruction hydrocephalus has developed. The reasons for this are unclear in

Fig. 11.18a This postcontrast CT image shows multiple metastases from a bronchial carcinoma. Now the radiation oncologists have to get to work. b The exterior CSF space is completely used up in this posterior fossa. A supratentorial obstruction hydrocephalus has developed. The reasons for this are unclear in this precontrast scan. c After contrast administration, the metastases in the posterior fossa are delineated with great clarity. The lesions themselves and the surrounding edema led to the obliteration of the exterior CSF spaces.

I Detection of Brain Metastases

Metastases Brain

Fig. 11.19 This image sequence illustrates the differential sensitivity of CTand MRI in diagnosing brain metastases. a This noncontrast CT could very well be reported as normal. b Even after contrast administration a lesion is difficult to appreciate. c It is the T2-weighted MRI that shows the associated edema in both occipital lobes (arrows). d The T1-weighted sequence after contrast administration just a little more superiorly suggests a vague contrast accumulation occipitally and another very small metastasis in the right frontal lobe (arrow). These are early brain metastases of a breast carcinoma.

Fig. 11.19 This image sequence illustrates the differential sensitivity of CTand MRI in diagnosing brain metastases. a This noncontrast CT could very well be reported as normal. b Even after contrast administration a lesion is difficult to appreciate. c It is the T2-weighted MRI that shows the associated edema in both occipital lobes (arrows). d The T1-weighted sequence after contrast administration just a little more superiorly suggests a vague contrast accumulation occipitally and another very small metastasis in the right frontal lobe (arrow). These are early brain metastases of a breast carcinoma.

Occipital Lymph Nodes Mri
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