Ultrafast Dynamic Contrast-enhanced MRI of the Breast: How Is It Used?

Abstract

Ultrafast dynamic contrast-enhanced (UF-DCE) MRI is a new approach to capture kinetic information in the very early post-contrast period with high temporal resolution while keeping reasonable spatial resolution. The detailed timing and shape of the upslope in the time-intensity curve are analyzed. New kinetic parameters obtained from UF-DCE MRI are useful in differentiating malignant from benign lesions and in evaluating prognostic markers of the breast cancers. Clinically, UF-DCE MRI contributes in identifying hypervascular lesions when the background parenchymal enhancement (BPE) is marked on conventional dynamic MRI. This review starts with the technical aspect of accelerated acquisition. Practical aspects of UF-DCE MRI include identification of target hypervascular lesions from marked BPE and diagnosis of malignant and benign lesions based on new kinetic parameters derived from UF-DCE MRI: maximum slope (MS), time to enhance (TTE), bolus arrival time (BAT), time interval between arterial and venous visualization (AVI), and empirical mathematical model (EMM). The parameters derived from UF-DCE MRI are compared in terms of their diagnostic performance and association with prognostic markers. Pitfalls of UF-DCE MRI in the clinical situation are also covered. Since UF-DCE MRI is an evolving technique, future prospects of UF-DCE MRI are discussed in detail by citing recent evidence. The topic covers prediction of treatment response, multiparametric approach using DWI-derived parameters, evaluation of tumor-related vessels, and application of artificial intelligence for UF-DCE MRI. Along with comprehensive literature review, illustrative clinical cases are used to understand the value of UF-DCE MRI.

Keywords: breast; compressed sensing; dynamic contrast enhanced; magnetic resonance imaging; ultrafast.

Fig. 1

The figure shows the relationship between SNR and the number of iterations, which stabilizes SNR with various T1 values using the NIST phantom using the NIST phantom. Initially, SNR increases with increasing number of iterations. The ranges of number of iterations which achieve plateau SNR and demonstrated N.S. are considered stable. The ranges of number of iterations differ among various T1 values. N.S., no significant difference.

Fig. 2

Exemplary results for the time–intensity curves in the aorta (a) and malignant lesion (b) for different numbers of iterations. The signal difference between pre- and post-contrast images is higher for larger numbers of iterations. This effect is larger for the aorta than for the lesion, and the required minimum number of iterations stabilizing the time–intensity curve is larger for the aorta. (From reference 14.

Fig. 3

Invasive carcinoma (ER negative, PR negative, HER2 negative, and apocrine type) of the right breast and DCIS of the left breast in woman in her 70s. Two masses in the right breast (arrows) with surrounding tumor-related vessels (arrowheads) are clearly depicted on MIP image of the 12th frame of UF-DCE MRI (a). In contrast, NME in the left breast is barely visible on the 12th frame. On MIP image of the 20th (last) frame of UF-DCE MRI (b), surrounding vessels are increased in number in the right breast. Multiple NME becomes visible on the 20th frame (arrows). MIP, maximum intensity projection.

Fig. 4

Invasive carcinoma of the left breast in woman in her 40s. On the 4th phase of UF-DCE MRI (a), the enhanced two masses are clearly delineated. On the early phase of dynamic contrast-enhanced MRI (b), the masses are surrounded and masked by marked BPE.

Fig. 5

Schema comparing kinetic analysis of UF-DCE MRI in early upslope with three-point BI-RADS curve analysis. Compared to BI-RADS curve analysis, UF-DCE MRI looks at the early upslope.

Fig. 6

Schema for kinetic parameters used in UF-DCE MRI. There are mainly four kinds of kinetic parameters: slope, time, interval, and modeling. Refer to the text for detailed definition and explanations of each parameter.

Fig. 7

Maximum slope and time to enhancement. MS is defined as the slope of the tangent (%/s) along the steepest part of the curve. TTE is defined as “The time point where the lesion starts to enhance” minus “the time point where the aorta starts to enhance.” MS, maximum slope; TTE, time to enhancement.

Fig. 8

Fibrocystic change in a 46-year-old woman. (a) Axial first-phase image of conventional dynamic contrast-enhanced MRI shows non-mass enhancement (NME) with focal distribution and heterogeneous internal enhancement (arrow). (b) The conventional kinetic curve of this NME is a fast wash-out pattern. This NME is classified as BI-RADS category 4. (c) Axial UF-DCE MRI image shows the NME. (d) Kinetic curve obtained from UF-DCE MRI can be useful in identifying relatively hypervascular benign lesion including fibrocystic change. NME, nonmass enhancement. (modified from Reference 4)

Fig. 9

A 71-year-old woman diagnosed with DCIS by ultrasound-guided biopsy. The case was finally diagnosed as high-grade DCIS by surgery. Heterogeneous enhancement was found in the UF-DCE MRI (a), as well as the early phase of dynamic contrast-enhanced MRI (b). Texture analysis reflects heterogeneity of enhancement within DCIS lesion. DCIS, ductal carcinoma in situ.

Fig. 10

Appearances of DCIS on UF-DCE MRI and the early phase of DCE MRI in relation to BPE. Female patient in her 40s presenting with DCIS (high grade) with microinvasion. UF-DCE MRI (a) revealed NME with segmental distribution without clustered ring enhancement. On the early phase of DCE MRI (b), the lesion appears slightly larger than that on UF-DCE, partly associated with clustered ring enhancement. Schema comparing enhanced area on UF-DCE and early phase of DCE MRI is shown in (c).