To investigate the nature of artifacts caused by air and chemical shift by fat, a test tube phantom study was performed in 2.0T and 0.5T superconducting magnetic resonance imaging systems in various imaging sequences. Spatial mismapping and signal change made image distortion in spin echo images of the air-column and severe signal voids in gradient echo images. Chemical shift artifacts appeared in the planes of frequency-encoding axis as crescent-shaped signal voids and summated bright signals, Both artifacts were more prominent in high field strength, Images at 0.5T showed more severe artifacts in the T2-weighted images than those in the other sequences. As the acquisition matrix increased, truncation artifacts decreased and susceptibility artifacts in gradient echo images diminished. Familiarity with causes, appearances and mechanisms of various artifacts will help radiologists for interpretation of MRI.
Artifacts* ; Magnetic Resonance Imaging* ; Recognition (Psychology)

The MR images of 13 patients with brain abscesses were retrospectively reviewed. The abscesses were solitary in 11 patients and multiple in 2 patients. They were located in the corticomedullary junction of the cerebral hemispheres(11) and cerebellum (2).: The sizes of the abscesses were variable, ranging from 1 cm to 5 cm in diameter. They were round (5), oblong (4) or multilobulated (4) in shape. Massive surrounding edema was found in 12 patients. The signal intensity of the abscess contents was hypointense to gray matter and hyperintense to CSF on T1-weighted images, and hyperintense to gray matter on both proton-density-and T2-weighted images. In 5 patients the abscess contents were heterogeneous on both T1-and T2-weighted images. The signal intensity of the abscess walls was isointense(11), slightly hyperintense (1) or hypointense (1) relative to gray matter on T1-weighted images, whereas they were isointense (4) or hypointense (9) on T2-weighted images. Of 10 patients with Gd-enhanced-T1-weighted images, 5 patients(50%) showed thin, smooth, rim enhancement, while the other 5 patients revealed somewhat irregular thick wall enhancement Satellite or daughter abscesses were found in 6 patients. Meningeal or ventricular wall enhancement suggesting meningitis or ventriculitis was associated in 3 and 1 patient, respectively. In conclusion, the characteristic morphology and intensity of the abscess capsule, massive surrounding edema, satellite abscess and associated meningitis or ventriculitis are characteristics of the brain abscess, even though they are not entirely specific to allow for accurate diagnosis in all patients.
Abscess ; Brain Abscess* ; Brain* ; Cerebellum ; Diagnosis ; Edema ; Gray Matter ; Humans ; Magnetic Resonance Imaging* ; Meningitis ; Nuclear Family ; Retrospective Studies

No abstract available.
Thumb*

Neural tube defects are reported one of the important congenital malformation in the world, with an incidence of 1.4 to 2 per 1000 pregnancies. Maternal serum AFP at the second trimester is used as screening test. But this is associated with numerous causes, including twins, fetal death, misdated pregnancies, cystic hygromas, teratomas, renal abnormalities, esophageal atresia and aberrations in the placenta. If the AFP level was elevated, targeted ultrasonography should be evaluated for confirming the gestational age and fetal viability, fetal number. Then if the ultrasonographic examination is nondiagnostic, or if an NTD is suspected, amniotic fluid AFP should be measured with acetylcholinesterase. But the false positive rate of the AF-AFP is high, and there is 0.3% of the false positive rate in amniotic acetylcholinesterase. This time the women with normal ultrasonographic examination continue the pregnancy after counseling of family history, past history with follow up of ultrasonography. We report a case with elevated second trimester MS-AFP, AF-AFP and positive amniotic acetylcholinesterase, but in which repeated sonographic findings were normal and result in delivery of a healthy baby without anomalies.
Acetylcholinesterase* ; Amniotic Fluid ; Counseling ; Esophageal Atresia ; Female ; Fetal Death ; Fetal Viability ; Follow-Up Studies ; Gestational Age ; Humans ; Incidence ; Lymphangioma, Cystic ; Mass Screening ; Neural Tube Defects ; Placenta ; Pregnancy Trimester, Second ; Pregnancy* ; Teratoma ; Ultrasonography

No abstract available.
Lung*

The purpose of this study is to describe the magnetic resonance imaging (MR) findings of metastatic brain tumors with emphasis on the signal intensities of the lesion on MR. Thirty four patients with intracranial metastases were studies with MR imaging. The diagnosis was established on the basis of either brain biopsy or combination of brain MR findings and the presence of primary tumors. The primary tumors include lung cancer (n=18), breast cancer (n=3), stomach cancer (n=3), rectal cancer (n=1), renal cell carcinoma (n=1), hepatocellular carcinoma(n=1), ovarian cancer (n=1), thyroid cancer (n=1), melanoma (n=1) and unknown primary sites (n=4). The parenchymal lesions were solitary in 35% (12/34) and multiple in 65% (22/34). The size of the lesions was variable, ranging from several millimeters to 5cm in diameter. The corticomedullar junction of the cerebral heispheres was the most common location of the lesions (68%). The signal intensity of solid portion of the lesions was usually either isointense (44%) or hypointense (29%) on T1-weighted images, whereas it appeared in isointense (47%), hypointense (8%) or hyperintense (11%) on proton density-weighted or T2-weighted images. The remaining cases showed mixed signal intensities. The enhancement patterns were variable including nodular (<1cm) (6%), homogenous (19%), heterogeneous (10%), ring-like enhancement (22%) or mixed pattern(43%). The size of surrounding edema was larger than the tumor diameter in 76%. In conclusion, although there are no specific MR findings of intracranial metastasis except multiplicity, intracranial metastasis should be included in differential diagnosis with high priority, when a solitary mass showing isointensity on boty T1-and T2-weighted images with massive surrounding edema, especially in the corticomedullary junction of the cerebral hemispheres is encountered.
Biopsy ; Brain Neoplasms* ; Brain* ; Breast Neoplasms ; Carcinoma, Renal Cell ; Cerebrum ; Diagnosis ; Diagnosis, Differential ; Edema ; Humans ; Lung Neoplasms ; Magnetic Resonance Imaging ; Melanoma ; Neoplasm Metastasis ; Ovarian Neoplasms ; Protons ; Rectal Neoplasms ; Stomach Neoplasms ; Thyroid Neoplasms

The purpose of this study is to describe the magnetic resonance imaging (MR) findings of metastatic brain tumors with emphasis on the signal intensities of the lesion on MR. Thirty four patients with intracranial metastases were studies with MR imaging. The diagnosis was established on the basis of either brain biopsy or combination of brain MR findings and the presence of primary tumors. The primary tumors include lung cancer (n=18), breast cancer (n=3), stomach cancer (n=3), rectal cancer (n=1), renal cell carcinoma (n=1), hepatocellular carcinoma(n=1), ovarian cancer (n=1), thyroid cancer (n=1), melanoma (n=1) and unknown primary sites (n=4). The parenchymal lesions were solitary in 35% (12/34) and multiple in 65% (22/34). The size of the lesions was variable, ranging from several millimeters to 5cm in diameter. The corticomedullar junction of the cerebral heispheres was the most common location of the lesions (68%). The signal intensity of solid portion of the lesions was usually either isointense (44%) or hypointense (29%) on T1-weighted images, whereas it appeared in isointense (47%), hypointense (8%) or hyperintense (11%) on proton density-weighted or T2-weighted images. The remaining cases showed mixed signal intensities. The enhancement patterns were variable including nodular (<1cm) (6%), homogenous (19%), heterogeneous (10%), ring-like enhancement (22%) or mixed pattern(43%). The size of surrounding edema was larger than the tumor diameter in 76%. In conclusion, although there are no specific MR findings of intracranial metastasis except multiplicity, intracranial metastasis should be included in differential diagnosis with high priority, when a solitary mass showing isointensity on boty T1-and T2-weighted images with massive surrounding edema, especially in the corticomedullary junction of the cerebral hemispheres is encountered.
Biopsy ; Brain Neoplasms* ; Brain* ; Breast Neoplasms ; Carcinoma, Renal Cell ; Cerebrum ; Diagnosis ; Diagnosis, Differential ; Edema ; Humans ; Lung Neoplasms ; Magnetic Resonance Imaging ; Melanoma ; Neoplasm Metastasis ; Ovarian Neoplasms ; Protons ; Rectal Neoplasms ; Stomach Neoplasms ; Thyroid Neoplasms

Intrathecal administration of methotrexate(IT-MTX) has constituted the standard approach to prophylaxis and treatment of central nevous system(CNS) leukemia. We experienced a quadriplegia and motor aphasia in a 14-year-old boy following repeated IT-MTX for the prophylaxis of meningeal leukemia. He was diagnosed as ALL without CNS involvement and treated by CCG- 1882 protocol. IT-MTX was administered for CNS prophylaxis. The patient began complaining of urinary incontinence, motor aphasia and weakness in his right leg from 12 days after the 5th dose of the IT-MTX therapy. Even though the IT-MTX was discontinued, loss of muscle power progressed upward resulting in quadriplegia. The patient showed slow and partial recovery on right extremities over 3 months. We report this case with brief review of literature.
Adolescent ; Aphasia, Broca* ; Extremities ; Humans ; Leg ; Leukemia ; Male ; Methotrexate* ; Quadriplegia* ; Urinary Incontinence

Magnetic resonance (MR) images of 14 consecutive patients with pathologically proven primary intracranial lymphoma were reviewed. All patients had a brain MR imaging before any treatment and were immunologically competent. MR images were acquired using 2.07 (n= 6) or 0.57 (n= 8) machine. The MR images were reviewed regarding the location, multiplicity, size, signal intensity, margin, shape, and the extent of surrounding edema of the lesion. Seven patients had multiple lesions, 2 to 4 in number. A total of 26 lesions was found; 25 were parenchymal lesions and one was dural lesion. The location of tumor was either central (r= 11) or peripheral (n= 14). The size of tumor was variable ranging from 0.6cm to 6.0cm in its maximal diameter. The tumors were isointense (n= 19) or hypointense (n= 7) relative to gray matter on T1-weighted images, isointense (n= 24) or hyperintense (n=2) on proton-density weighted images, and isointense (n= 21) or hyperintense (n= 5) on 78-weighted images. On gadolinium-enhanced T1-weighted images of 13 patients strong enhancement was seen in 22 of 23 lesions. Nineteen lesions showed smooth, well-defined margin, whereas remaining 7 lesions showed irregular, ill-defined margin. The shape of the tumor was diverse; round of ovoid (n= 15), lobulated (n= 9), or short linear (n= 2). These results suggest that one should consider the diagnosis of CNS lymphoma in cases with single or multiple masses that abut CSF space and show iso-or similar intensity to gray matter with strong enhancement on MR images.
Brain ; Diagnosis ; Edema ; Gray Matter ; Humans ; Lymphoma* ; Magnetic Resonance Imaging*