Dynamic MR imaging of patients with breast cancer—establishment and comparison of different analytical methods for tissue perfusion and capillary permeability
The present invention encompasses methods, apparatus, and computer based systems for identifying benign and malignant tumors in tissues such as soft tissues and particularly breast tissue using dynamic contrast-enhanced magnetic resonance imagining (DCE-MRI) and dynamic susceptibility contrast-enhanced magnetic resonance (DSC) imagining of the tumors. Some embodiments encompass the use of two dynamic MRI pulse sequences in intercalating mode during parenteral administration of an MR contrast substance, wherein one of said pulse sequences is optimized for spatial information and the other pulse sequence is adjusted for high temporal solution, the high-temporal dissolved sequence further comprising a double echo-collection sensitive towards both DCE and DSC for generating a number of different biomarker data such as pharmacokinetic biomarker data, descriptive DCE biomarkers and descriptive DSC biomarkers, and subsequently normalizing and comparing said data with corresponding data from corresponding benign and malign tumors, respectively.
1. A method for imaging tumors in soft tissues, said method comprising:
(a) administering an intravenous injection of contrast agent to a subject having a soft tissue tumor;
(b) applying to the soft tissue tumor, with a magnetic resonance imaging (MRI) machine, two alternating dynamic magnetic resonance imaging (MRI) pulse sequences prior to, during, and after administration of the contrast agent,
wherein one of said pulse sequences optimized for high spatial resolution and the other pulse sequence is optimized for high temporal resolution, and
wherein the high temporal resolution sequence further comprises a double-echo collection for both dynamic contrast enhanced (DCE) magnetic resonance imaging and dynamic susceptibility contrast (DSC) enhanced magnetic resonance imaging; and
(c) acquiring:
(i) a T1-weighted MRI image data set for the soft tissue tumor from the high spatial resolution sequence,
(ii) a T1-weighted MRI image data set for the soft tissue tumor from the dynamic contrast enhanced (DCE) echo of the high temporal resolution sequence, and
(iii) a T2*-weighted MRI image data set for the soft tissue tumor from the dynamic susceptibility contrast enhanced (DSC) echo of the high temporal resolution sequence.
2. The method of claim 1 further comprising:
(d) calculating:
(i) descriptive biomarkers from the DCE high temporal T1-weighted image data set;
(ii) quantitative pharmacokinetic biomarkers from the DCE high temporal T1-weighted image data set; and
(iii) quantitative pharmacokinetic biomarkers from the DSC high temporal T2*-weighted image data set.
3. The method of claim 2 , wherein the descriptive biomarkers are chosen from wash-in rate, wash-out rate, time to peak (TTP), peak enhancement (peak enh ), and area under the curve (AUC),
wherein the quantitative pharmacokinetic biomarkers from the DCE high temporal T1-weighted image data set are chosen from K trans , k ep , v e , and v p , and
wherein the quantitative pharmacokinetic biomarker from the DSC high temporal T2*-weighted image data set is absolute peak change in R2* (R2*-peak enh ).
4. The method of claim 3 , further comprising normalizing the calculated quantitative pharmacokinetic biomarkers from the DCE high temporal T1-weighted image data set to corresponding values collected from non-tumor parenchymal soft tissue.
5. The method of claim 1 , wherein the soft tissue is breast tissue.
6. The method of claim 1 , wherein the high temporal resolution is less than 3 seconds.
7. A method for distinguishing between benign and malignant breast tumors, said method comprising:
(a) performing the method of claim 4 ;
(b) comparing the calculated biomarkers with corresponding measurements from known benign breast tumors; and
(c) identifying the tumor as malignant if:
(i) the calculated time to peak (UP) is shorter than the corresponding TTP for known benign tumors;
(ii) the calculated normalized K trans is higher than the corresponding normalized K trans for known benign tumors; and/or
(iii) the calculated R2*-peak enh is higher than the corresponding R2*-peak enh for known benign tumors,
wherein said method is at least 90% accurate for distinguishing between benign and malignant breast tumors.
8. The method of claim 7 , wherein the high temporal resolution is less than 3 seconds.
9. The method of claim 7 , wherein the benign tumor is a fibroadenoma (FA) and the malignant tumor is an invasive ductal carcinoma (IDC), and
wherein said method is at least 98% accurate for distinguishing between the FA and IDC breast tumors.
10. The method of claim 9 , wherein the high temporal resolution is less than 3 seconds.