The Study Of Functional MRI (fMRI) In The Diagnosis Of Small Lesions Of Breast Cancers

Partâ… Diffusion-weighted MRI of the breast with GRAPPA:initial experienceObjective:To evaluate prospectively the improvement of the image quality with the use of generalized autocalibrating partially parallel acquisitions(GRAPPA) in diffusion-weighted imaging(DWI) of the breast and its effect on apparent diffusion coefficient(ADC) measurements.Materials and methods:Twenty-eight women underwent echo-planar(EPI)-DWI of the breast with conventional phase encoding and with GRAPPA,respectively.The b value of 800s/mm² was used in conventional DWI group,while two b values of 800 and 1000s/mm² were used in GRAPPA-DWI groups.Image quality,signal-to-noise ratio(SNR) and ADC values of breast were compared with different series at the same b value of 800s/mm² and with different b values of 800 and 1000s/mm² in GRAPPA DWI groups.Matched-pairs Wilcoxon signed rank test was used for statistical analysis.Results:Higher image quality score and SNR value of the breast were obtained in GRAPPA-DWI group than those in conventional DWI group with the same b value of 800s/mm² and the differences were statistically significant(P＜0.01).The mean ADC of breast in GRAPPA-DWI group was lower than that in conventional DWI group with the same b value of 800s/mm²,but there was no significant difference between the two sequences for breast ADC measurement(P＞0.05).In GRAPPA-DWI groups,the image quality score at b value of 800s/mm² was slightly higher than that at b value of 1000s/mm² and there was no significant difference between them(P＞0.05). The SNR value and the mean ADC of breast at b value of 800s/mm² were higher than those at b value of 1000s/mm² in GRAPPA-DWI groups and the differences were statistically significant(P＜0.05).Conclusion:GRAPPA is useful in improving image quality and SNR of EPI-DWI of breast without compromising ADC measurements. Partâ…¡Comparative study of diffusion weighted imaging and dynamic contrast-enhanced MRI for the detection of small lesions of breast cancersObjective:To compare the sensitivity of DWI with dynamic contrast-enhanced(DCE) MRI for the detection of small lesions of breast cancers and to evaluate the clinical value of DWI.Materials and methods:Forty-eight patients with benign(n=25) and malignant (n=45) small lesions of breast(≤2 cm) proved by pathology underwent DWI and DCE-MRI.The DCE-MRI was performed using FLASH sequence and the time-signal intensity curve was drawn.The DWI was performed using GRAPPA-EPI sequence with different b value(800,1000sec/mm²) and the ADC values of lesions were measured.The sensitivity and specificity of DWI for the detection of small lesions were compared with those of DCE-MRI.Results:Forty of 45 small lesions of breast cancers and 19 of 25 small lesions of benign breast were correctly diagnosed using DCE-MRI.The sensitivity,specificity and positive predictive value of diagnosis of TIC were 88.9%(40/45),76.0%(19/25) and 87.0%(40/46).With b values of 800 s/mm² and 1000 s/mm²,the average ADC values of lesions were(1.153±0.192)×10^-3 and(1.079±0.186)×10^-3mm²/s,while those of benign ones were(1.473±0.252)×10^-3 and(1.419±0.255)×10^-3mm²/s,respectively. There was no significant difference for the ADC values with different b values in the same group(P＞0.05),while there was a significant difference between the malignant and the benign groups(P＜0.05).Thirty-nine of 45 malignant small lesions and 19 of 25 benign small lesions were correctly diagnosed using DWI with b value of 1000 s/mm².The sensitivity,specificity and positive predictive value of diagnosis of DWI were 86.7%(39/45),76.0%(19/25) and 86.7%(39/45),respectively.The ability of DWI in discriminating the small breast cancer from benign one was in accordance with that of DCE-MRI.The sensitivity(93.3%),specificity(84.0%) and positive predictive value(91.3%) were improved with the combination of DCE-MRI and DWI.Conclusion:DWI has a high sensitivity for the detection of small lesions of breast cancers,the ADC value can provide valuable information in the differential diagnosis. Partâ…¢Preliminary application of parametric perfusion-weighted imaging in diagnosis of small breast cancersObjective To study the imaging features of small breast cancers and its characterization of perfusion on parametric images,and to evaluate the clinical value of parametric MR perfusion-weighted imaging.Methods 29 women with 46 pathologically confirmed small breast cancers(≤2 cm) underwent DCE-MRI.DCE-MRI was performed using FLASH sequence and the time-signal intensity curve(TIC) was obtained.From 3 selected time points,the parametric perfusion images of Washin,Washout,maximum intensity projection over time(MIPt) and positive enhancement integral(PEI) were derived with special software of breast evaluation in MRI.The parameters of perfusion were measured respectively,and then the features of perfusion of small breast cancers were analyzed.Results 41,19,44 and 45 small lesions of breast cancers were found in four kinds of parametric images of Washin,Washout,MIPt and PEI,respectively.The sensitivities for the detection of small lesions were 89.1%,41.3%,95.7%and 97.8% respectively.4 among 5 small lesions(80.0%) missed in Washin images,showed TIC of typeâ… .15 among 19 small lesions(78.9%) found in Washout images,showed TIC of typeâ…¢.35 small lesions(76.1%) showed significantly inhomogeneous enhancement in all 46 lesions and 26 of them specialized in obvious peripheral enhancement.There was a significant difference between the parameters of lesions and normal breast tissue(P＜0.05).Moreover,the difference of parameters between periphery and centre of lesions is also significant(P＜0.05).Conclusion High-spatial-resolution parametric perfusion-weighted imaging has a high sensitivity for the detection of small lesions of breast cancers.Most of small lesions shows significantly inhomogeneous enhancement.In addition,parametric perfusion-weighted imaging of the breast could provide valuable information in the differential diagnosis.