[Perfusion-index values evaluated by dynamic magnetic resonance imaging in advanced rectal carcinoma. A new predictor of response to preoperative radiochemotherapy?]

Quantitative analysis of 3-Tesla magnetic resonance imaging in the differential diagnosis of breast lesions

The aim of this study was to investigate the value of quantitative 3-Tesla (3T) magnetic resonance (MR) assessment in the diagnosis of breast lesions. A total of 44 patients with breast lesions were selected. All the patients underwent MR plain scanning and T1 dynamic contrast-enhanced imaging. The vascular function parameters of the lesions, namely volume transfer constant (Ktrans), rate constant (Kep), extravascular extracellular volume fraction (Ve) and integrated area under the curve (iAUC), were acquired. These parameters were compared between benign and malignant breast lesions, and also among differential grades of invasive ductal carcinoma. The values of Ktrans, Kep and iAUC were significantly different between the benign and malignant tumors; however, the values of Ve in the benign and malignant tumors were not significantly different. The values of Ktrans, Kep and iAUC in invasive ductal carcinoma were significantly different between grade I and grade II, and between grade I and grade III; however, there was no significant difference between grade II and grade III. The Ve values in invasive ductal carcinoma did not significantly differ among grades I, II and III. Among the vascular function parameters, Ktrans exhibited the highest sensitivity and specificity in the differentiation of benign and malignant lesions. Quantitative 3-T MR assessment is valuable in the diagnosis of benign and malignant breast lesions. It can also provide reference values for the differentiation of the histological grade of breast invasive ductal carcinoma.

Is there a benefit in using magnetic resonance imaging in the prediction of preoperative neoadjuvant therapy response in locally advanced rectal cancer?

OBJECTIVE

This meta-analysis aimed to evaluate the accuracy of magnetic resonance imaging (MRI) in predicting responses in patients with locally advanced rectal cancer after preoperative neoadjuvant therapy.

METHODS

Articles in English language relating to the accuracy of MRI for this utility were retrieved. Methodological quality was assessed by Quality Assessment of Diagnostic Accuracy Studies tool. Pooled estimation and subgroup analysis data were obtained by statistical analysis.

RESULTS

Fourteen studies involved 751 pathologically confirmed patients met the inclusion criteria. Methodological quality was relatively high. To predict histopathological response in locally advanced rectal cancer by MRI, the pooled sensitivity and specificity were 0.78 [95 % confidence intervals (CI), 0.65, 0.87] and 0.81 (95 % CI, 0.72, 0.87), respectively. Positive likelihood ratio and negative likelihood ratio were 4.1 (95 %CI, 2.9, 5.8) and 0.27 (95 % CI, 0.17, 0.43), respectively. Subgroup analysis showing that imaging was performed at 3.0 T MRI devices had higher pooled sensitivity (0.92, 95 % CI, 0.84, 1.00) than the subgroup of MRI with ≤1.5 T (0.68, 95 % CI, 0.53, 0.82) (p < 0.05).The sensitivity and specificity of T2-weighted imaging (T2WI) with diffusion-weighted imaging (DWI) were 0.92 (95 % CI, 0.81, 1.00) and 0.75 (95 % CI, 0.54, 0.95); those of T2WI alone were 0.64 (95 % CI, 0.47, 0.82) and 0.88 (95 % CI, 0.81, 0.94) (p > 0.05).

CONCLUSION

This meta-analysis indicates that MRI is an accurate tool in predicting pathologic response after preoperative therapy in patients with locally advanced rectal cancer. It is suggested to perform MRI by 3.0 T devices, which might be sensitive to identify responder. The addition of DWI to T2WI showed a non-significant improvement in sensitivity, which deserves further investigation.

Monitoring of liver metastases after stereotactic radiotherapy using low-MI contrast-enhanced ultrasound--initial results

The purpose of this study was to monitor liver metastases after radiotherapy using contrast-enhanced ultrasound (CEUS). In 15 patients, follow-up examinations after stereotactic, single-dose radiotherapy were performed using CEUS (low mechanical index (MI), 2.4-ml SonoVue) and computed tomography (CT). Besides tumor size, the enhancement of the liver and the metastases was assessed at the arterial, portal venous, and delayed phases. The sizes of the tumor and of a perifocal liver reaction after radiotherapy measured with CEUS significantly correlated with those measured at CT (r=0.93, p<0.001). CEUS found a significant reduction of the arterial vascularization in treated tumors (p<0.05). In the arterial phase, the perifocal liver tissue was hypervascularized compared to the treated tumor (p<0.001); in the late phase, it was less enhanced than the liver (p<0.001) and more than the tumor (p<0.01). The perifocal liver reaction was also seen in CT, but with a variable enhancement at the arterial (50% hyperdense compared to normal liver tissue), venous, or delayed phase (each with 70% hyperdense reactions). CEUS allows for the assessment of tumor and liver perfusion, in addition to morphological tumor examination, which was comparable with CT. Thus, changes of tumor perfusion, which may indicate tumor response, as well as the perifocal liver reaction after radiotherapy, which must be differentiated from perifocal tumor growth, can be sensitively visualized using CEUS.