[Correlation between age and average apparent diffusion coefficient in normal-appearing cerebral white matter].

OBJECTIVE: To quantitatively study the effect of ages on the average apparent diffusion coefficient (ADCav) of normal-appearing white matter. METHODS: Fifty patients with normal-appearing white matter were divided into four age groups, namely 16-30 years, (n=13), 31-45 years (n=12), 46-60 years (n=14) and >60 years (n=11). All the subjects were examined with conventional and trace-weighted diffusion imaging in three orthogonal directions. The ADCav of the white matter was measured and compared between various age groups. RESULTS: In the white matter, the ADCav of all the patients was (0.71+/-0.08) x 10(-3) mm2/s; the ADCav of the white matter in the first to fourth age groups were (0.69+/-0.06) x 10(-3) mm2/s, (0.71+/-0.07) x 10(-3) mm2/s, (0.71+/-0.09) x 10(-3) mm2/s, and (0.73+/-0.10) x 10(-3) mm2/s respectively. ADCav of patients between 16-30 years was significantly different from that of patients over 60 years of age (P=0.014). Patients older than 60 years had an ADCav of the white matter significantly higher than the value of (0.70+/-0.07) x 10(-3) mm2)/s in the total patients younger than 60 years (P=0.026). CONCLUSION: Water diffusibility shows a slight increase in human white matter with aging, possibly due to mild ultrastructural changes associated with aging.

Perfusion homogeneity of hepatic parenchyma in magnetic resonance imaging during splenoportography.

OBJECTIVE: To evaluate the homogeneity of hepatic parenchyma enhancement in magnetic resonance imaging during splenoportography (MRSP) in the portal phase. METHODS: MRSP was performed in 16 patients suspected of space-occupying lesions in the livers. The signal intensity of non-lesion abnormal perfusion areas and that of peripheral parenchyma were measured in all the scanning phases including unenhanced phase, portographic phase, equilibrium phase, and delayed phase. RESULTS: Perfusion abnormalities were observed in 8 non-lesion foci in the portal phase in 4 cases of hepatic cirrhosis, most frequently appearing in triangle or fan-like shapes (7/8) with unpredictable locations. Hepatic cirrhosis patients had more non-lesion perfusion abnormalities than non-cirrhosis patients. CONCLUSIONS: The presence of non-lesion perfusion abnormalities in MRSP does not affect the diagnosis of the disease, and more homogeneous enhancement of the hepatic parenchyma in the portal phase can be achieved in MRSP than in CT during arterial portography and magnetic resonance imaging during arterial portography.

[Comparative study of four GRE sequences in MnDPDP-enhanced magnetic resonance imaging for primary hepatocellular carcinoma].

OBJECTIVE: To assess the value of four T(1)-weighted (T(1)W) gradient-recalled-echo (GRE) sequences in MnDPDP-enhanced magnetic resonance imaging (MRI) for diagnosing primary hepatocellular carcinoma (HCC). METHODS: T(1)W images of fast low-angle shot (FLASH), fat-suppressed (FS) FLASH, in-phase and opposed-phase (IP/OP) FLASH were obtained from 13 HCC patients before and 30 min after the patients were given 5 micromol/kg.b.w. MnDPDP. The delayed (24 h) images were also obtained with the same sequences in addition to the T(2)W turbo spin-echo (TSE) sequence performed before MnDPDP administration. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the liver parenchyma and the tumor foci were calculated for each sequence. RESULTS: No statistical differences were found in SNR and CNR between the images obtained with the four T(1)W sequences (P > 0.05). The fatty degeneration of HCC could be detected by OP imaging, but not by T(1)W FLASH or IP T(1)W imaging. CONCLUSION: IP and OP FLASH produces better and easier performance in characterizing the fatty degeneration of HCC, and are recommended for MnDPDP-enhanced MRI of HCC.

[Role of magnetic resonance imaging in the diagnosis of intracranial germinoma].

OBJECTIVE: To investigate the value of magnetic resonance imaging (MRI) in the diagnosis of intracranial germinoma. METHODS: A retrospective analysis of the MRI features was conducted in 19 cases of pathologically confirmed intracranial germinoma. RESULTS: The lesion was located in the sellar region in 10 cases, in the pineal region in 6 and in the thalamus and basal ganglia in 3. The characteristic MRI of intracranial germinoma included the following features: (1) In T1-weighted images (T1WI), the lesions were isointense or slightly hypointense, which appeared isointense or slightly hyperintense in T2-weighted images (T2WI). The germinoma in the sellar region and pineal region showed no edema, but those in the thalamus and basal ganglia showed minimal or moderate edema with space-occupying effect. (2) Homogeneous or inhomogeneous Gd-DTPA enhancement was observed in most of the tumors. CONCLUSION: Multiplanar imaging and Gd-DTPA enhancement in MRI are helpful in the diagnosis and differential diagnosis of intracranial germinoma, which presents features characteristic of the gender and age of the patients with the disease, location, size, form and image intensity of the lesion, and therefore, preoperative MRI diagnosis of the tumor can be possible.

Superparamagnetic iron oxide (Feridex)-enhanced MRI in diagnosis of focal hepatic lesions.

OBJECTIVE: To evaluate the diagnostic value of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) for hepatic focal solid lesions. METHODS: SPIO (Feridex)-enhanced MRI examination was performed in 28 cases of hepatic space-occupying lesions defined by CT or MRI or other methods. In post-contrast enhanced examination, the signal intensity and contrast-to-noise ratio (CNR) were measured in lesions and normal hepatic parenchyma in T2-weighted images (T2WI) and were compared with those in pre-contrast enhanced MRI. The number and morphology of the lesions were visualized for qualitative diagnostic analysis. RESULTS: In Feridex-enhanced MRI, the signal intensity of normal hepatic parenchyma was decreased while the CNR between lesions and normal liver tissues significantly improved in comparison with that in pre-contrast enhanced examination. CONCLUSION: Feridex-enhanced T2WI examination significantly improves detection of hepatic lesions and is valuable in diagnosing hepatic focal solid lesions.

Animal experiments and clinical application of CT during percutaneous splenoportography.

AIM:To introduce computed tomography during percutaneous splenoportography (CTSP), a new method for determining hepatic diseases.METHODS:Ten hybrid dogs and 20 patients with primary hepatic cancer (PHC) were included in the study. Each dog was examined by CT, CTAP (computed tomography during arterial portography) and CTSP to compare the enhanced degrees of the liver. The 20 PHC patients were examined by CTSP and the appearance of PHC was compared with their pathological results to evaluate the diagnostic significance of CTSP.RESULTS:The animal experiments showed that both CTAP and CTSP could obviously enhance the liver (P < 0.01), but there was no significant difference in the enhanced results between the two methods (P >0.05). On the CTSP images in the 20 patients, the density of the livers was increased to 168-192Hu, whereas the density of the cancers remained as low as that on the images of CT scans (< 58Hu). The CTSP findings were consistent with the surgical ones from spaceoccupying lesions. Its diagnostic value was obviously superior to that of general enhanced CT and ultrasonic examination. However, it was difficult for CTSP to show nodules less than 1cm in size located on the surface of the liver or the hepatic portal zone.CONCLUSION:Like CTAP, CTSP is also a sensitive method for showing occupants in the liver. But the equipments and the procedures for CTSP are simpler than for CTAP. Therefore, it is an alternative procedure in clinical practice.