Additional Medical Terms • CHAPTER 9 437
magnetic resonance imaging
(MRI)
măg-NĔT-ĭc RĔZ-ĕn-ăns
ĬM-ĭj-ĭng
positron emission
tomography (PET)
PŎZ-ĭ-trŏn ē-MĬSH-ŭn
tō-MŎG-ră-fē
tom/o: to cut
-graphy: process of
recording
Radiographic technique that uses electromagnetic energy to produce multiplanar
cross-sectional images of the body
MRI of the brain produces cross-sectional, frontal, and sagittal plane views of the brain.
It is regarded as superior to CT for most CNS abnormalities, particularly those of the
brainstem and spinal cord. A contrast medium is not required but may be used to
enhance internal structure visualization.
Radiographic technique that combines computed tomography with radiopharma-
ceuticals to produce a cross-sectional (transverse) image of the dispersement of
radioactivity (through emission of positrons) in a section of the body, revealing areas
where the radiopharmaceutical is metabolized and where metabolism is deficient
PET scanning aids in diagnosis of such neurological disorders as brain tumors, epilepsy,
stroke, Alzheimer disease, and abdominal and pulmonary disorders.
Medical and Surgical Procedures
Endocrine System
Minimally invasive endoscopic surgery that removes pituitary tumors through the
nasal cavity via the sphenoid sinus (transsphenoidal) without affecting brain tissue
(See Fig. 9–13.)
Although most tumors can be removed via transsphenoidal hypophysectomy, some large
tumors may need to be removed via transfrontal craniotomy (entry through the frontal
bone of the skull).
transsphenoidal
hypophysectomy
trăns-sfē-NOY-dăl hī-pō-
fĭ-SĔK-tō-mē
Endoscopic
incision
Endotracheal
tube
Sphenoid
sinus
Speculum
Pituitary tumor
Figure 9-13Transsphenoidal hypophysectomy. (A)Incision beneath the upper lip to enter
the nasal cavity and gain access to the pituitary gland. (B)Insertion of a speculum and special
forceps to remove the pituitary tumor.