The use of MRI apparent diffusion coefficient (ADC) in monitoring the development of brain infarction.

BACKGROUND: To study the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. METHODS: 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC) values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. RESULTS: The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P < 0.01). The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. CONCLUSION: The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction.

[Imaging manifestation and clinical value in herniation pit of femoral neck].

OBJECTIVE: To discuss the imaging manifestation and clinical value in herniation pit of femoral neck. METHODS: One case proved by operation and pathology and twenty cases with typical imaging manifestation described by Pitt were reviewed retrospectively. There were 17 males and 4 females with an average age of 53 years old(ranging from 30 to 85 years). All cases were examined by X-ray films and CT, and 13 cases were performed with MRI. RESULTS: Twenty-nine lesions were found in the 21 cases, 9 cases were in right side, 8 cases were in left side, 4 cases were in both sides. The lesions were all located in the superior lateral part of the femoral neck and anterior lateral base of femoral head. The lesions were round or oval, and most of their greatest diameter was less than 16 mm. X-ray films showed a central radiolucency with a thin clear sclerotic rim or simple sclerotic loop. CT scans showed a well-defined lesion of soft-tissue attenuation with sclerotic margin. The lesions had focal cortical perforation. On MRI images,most lesions showed uniformly long T1 and long T2 fluid signal intensity. CONCLUSION: Herniation pit of femoral neck have some specific imaging features, CT can make accurate diagnosis. X-ray and MRI are helpful to diagnosis.