Heinrich Magometschnigg

Improved Differentiation of Benign and Malignant Breast Tumors with Multiparametric 18Fluorodeoxyglucose Positron Emission Tomography Magnetic Resonance Imaging: A Feasibility Study

Purpose: To assess whether multiparametric 18fluorodeoxyglucose positron emission tomography magnetic resonance imaging (MRI) (MP 18FDG PET-MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), three-dimensional proton MR spectroscopic imaging (3D 1H-MRSI), and 18FDG-PET enables an improved differentiation of benign and malignant breast tumors. Experimental Design: Seventy-six female patients (mean age, 55.7 years; range, 25–86 years) with an imaging abnormality (BI-RADS 0, 4–5) were included in this Institutional Review Board (IRB)-approved study. Patients underwent fused PET-MRI of the breast with 18FDG-PET/CT and MP MRI at 3T. The likelihood of malignancy was assessed for all single parameters, for MP MRI with two/three parameters, and for MP 18FDG PET-MRI. Histopathology was used as the standard of reference. Appropriate statistical tests were used to assess sensitivity, specificity, and diagnostic accuracy for each assessment combination. Results: There were 53 malignant and 23 benign breast lesions. MP 18FDG PET-MRI yielded a significantly higher area under the cure (AUC) of 0.935 than DCE-MRI (AUC, 0.86; P = 0.044) and the combination of DCE-MRI and another parameter (AUC, 0.761–0.826; P = 0.013–0.020). MP 18FDG PET-MRI showed slight further improvement to MP MRI with three parameters (AUC, 0.925; P = 0.317). Using MP 18FDG PET-MRI there would have been a reduction of the unnecessary breast biopsies recommended by MP imaging with one or two parameters (P = 0.002–0.011). Conclusion: This feasibility study shows that MP 18FDG PET-MRI enables an improved differentiation of benign and malignant breast tumors when several MRI and PET parameters are combined. MP 18FDG PET-MRI may lead to a reduction in unnecessary breast biopsies. Clin Cancer Res; 20(13); 3540–9. ©2014 AACR.

Diffusion-weighted imaging of breast lesions: Region-of-interest placement and different ADC parameters influence apparent diffusion coefficient values

ObjectivesTo investigate the influence of region-of-interest (ROI) placement and different apparent diffusion coefficient (ADC) parameters on ADC values, diagnostic performance, reproducibility and measurement time in breast tumours.MethodsIn this IRB-approved, retrospective study, 149 histopathologically proven breast tumours (109 malignant, 40 benign) in 147 women (mean age 53.2) were investigated. Three radiologists independently measured minimum, mean and maximum ADC, each using three ROI placement approaches:1 – small 2D-ROI, 2 – large 2D-ROI and 3 – 3D-ROI covering the whole lesion. One reader performed all measurements twice. Median ADC values, diagnostic performance, reproducibility, and measurement time were calculated and compared between all combinations of ROI placement approaches and ADC parameters.ResultsMedian ADC values differed significantly between the ROI placement approaches (p < .001). Minimum ADC showed the best diagnostic performance (AUC .928–.956), followed by mean ADC obtained from 2D ROIs (.926–.94). Minimum and mean ADC showed high intra- (ICC .85–.94) and inter-reader reproducibility (ICC .74–.94). Median measurement time was significantly shorter for the 2D ROIs (p < .001).ConclusionsROI placement significantly influences ADC values measured in breast tumours. Minimum and mean ADC acquired from 2D-ROIs are useful for the differentiation of benign and malignant breast lesions, and are highly reproducible, with rapid measurement.Key Points• Region of interest placement significantly influences apparent diffusion coefficient of breast tumours.• Minimum and mean apparent diffusion coefficient perform best and are reproducible.• 2D regions of interest perform best and provide rapid measurement times.

Molecular imaging for the characterization of breast tumors

Recently, molecular imaging, using various techniques, has been assessed for breast imaging. Molecular imaging aims to quantify and visualize biological, physiological, and pathological processes at the cellular and molecular levels to further elucidate the development and progression of breast cancer and the response to treatment. Molecular imaging enables the depiction of tumor morphology, as well as the assessment of functional and metabolic processes involved in cancer development at different levels. To date, molecular imaging techniques comprise both nuclear medicine and radiological techniques. This review aims to summarize the current and emerging functional and metabolic techniques for the molecular imaging of breast tumors.

Quantitative Assessment of Breast Parenchymal Uptake on 18F-FDG PET/CT: Correlation with Age, Background Parenchymal Enhancement, and Amount of Fibroglandular Tissue on MRI

Background parenchymal enhancement (BPE), and the amount of fibroglandular tissue (FGT) assessed with MRI have been implicated as sensitive imaging biomarkers for breast cancer. The purpose of this study was to quantitatively assess breast parenchymal uptake (BPU) on 18F-FDG PET/CT as another valuable imaging biomarker and examine its correlation with BPE, FGT, and age. Methods: This study included 129 patients with suspected breast cancer and normal imaging findings in one breast (BI-RADS 1), whose cases were retrospectively analyzed. All patients underwent prone 18F-FDG PET/CT and 3-T contrast-enhanced MRI of the breast. In all patients, interpreter 1 assessed BPU quantitatively using SUVmax. Interpreters 1 and 2 assessed amount of FGT and BPE in the normal contralateral breast by subjective visual estimation, as recommended by BI-RADS. Interpreter 1 reassessed all cases and repeated the BPU measurements. Statistical tests were used to assess correlations between BPU, BPE, FGT, and age, as well as inter- and intrainterpreter agreement. Results: BPU on 18F-FDG PET/CT varied among patients. The mean BPU SUVmax ± SD was 1.57 ± 0.6 for patients with minimal BPE, 1.93 ± 0.6 for mild BPE, 2.42 ± 0.5 for moderate BPE, and 1.45 ± 0.3 for marked BPE. There were significant (P < 0.001) moderate to strong correlations among BPU, BPE, and FGT. BPU directly correlated with both BPE and FGT on MRI. Patient age showed a moderate to strong indirect correlation with all 3 imaging-derived tissue biomarkers. The coefficient of variation for quantitative BPU measurements with SUVmax was 5.6%, indicating a high reproducibility. Interinterpreter and intrainterpreter agreement for BPE and FGT was almost perfect, with a κ-value of 0.860 and 0.822, respectively. Conclusion: The results of our study demonstrate that BPU varied among patients. BPU directly correlated with both BPE and FGT on MRI, and BPU measurements were highly reproducible. Patient age showed a strong inverse correlation with all 3 imaging-derived tissue biomarkers. These findings indicate that BPU may serve as a sensitive imaging biomarker for breast cancer prediction, prognosis, and risk assessment.

Molecular breast imaging. An update

CLINICAL/METHODICAL ISSUE The aim of molecular imaging is to visualize and quantify biological, physiological and pathological processes at cellular and molecular levels. Molecular imaging using various techniques has recently become established in breast imaging. STANDARD RADIOLOGICAL METHODS Currently molecular imaging techniques comprise multiparametric magnetic resonance imaging (MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), proton MR spectroscopy ((1)H-MRSI), nuclear imaging by breast-specific gamma imaging (BSGI), positron emission tomography (PET) and positron emission mammography (PEM) and combinations of techniques (e.g. PET-CT and multiparametric PET-MRI). METHODICAL INNOVATIONS Recently, novel techniques for molecular imaging of breast tumors, such as sodium imaging ((23)Na-MRI), phosphorus spectroscopy ((31)P-MRSI) and hyperpolarized MRI as well as specific radiotracers have been developed and are currently under investigation. PRACTICAL RECOMMENDATIONS It can be expected that molecular imaging of breast tumors will enable a simultaneous assessment of the multiple metabolic and molecular processes involved in cancer development and thus an improved detection, characterization, staging and monitoring of response to treatment will become possible.ZusammenfassungKlinisches/methodisches ProblemDie molekulare Bildgebung zielt auf die Darstellung, Beschreibung und Quantifizierung biologischer, physiologischer und pathologischer Prozesse auf zellulärer und molekularer Ebene ab. In den letzten Jahren hat sich die molekulare Bildgebung mit ihren verschiedenen Modalitäten in der Brustdiagnostik etabliert.Radiologische StandardverfahrenDie molekularen Brustbildgebung umfasst derzeit die multiparametrische(MP)-MRT mit funktioneller und morphologischer kontrastmittelverstärkter MRT (KM-MRT), molekularer diffusionsgewichteter Bildgebung („diffusion-weighted imaging“, DWI) und metabolischer Protonenspektroskopie (1H-MRSI) sowie nuklearmedizinische Verfahren (brustspezifische Gammakamerabildgebung [BSGI], Positronenemissionstomographie [PET], PET-Mammographie [PEM]) und kombinierte Verfahren (PET-CT, MP-PET-MRT).Methodische InnovationenDie molekulare Bildgebung in der Mammadiagnostik ist ein sich rapide entwickelndes Forschungsfeld mit neuen vielversprechenden Techniken wie der Natriumbildgebung (23Na-MRT), der Phosphorspektroskopie (31P-MRSI) und der hyperpolarisierten MRT sowie neuen zielgerichteten Radiotracern und Kontrastmitteln.BewertungDer Einfluss der molekularen Brustbildgebung wird in den nächsten Jahren weiter zunehmen. Es ist zu erwarten, dass durch die molekulare Brustbildgebung eine optimierte Detektion und Charakterisierung von Brusttumoren, ein akkurates lokales und peripheres Staging sowie eine zielgerichtete Therapieverlaufskontrolle ermöglicht werden wird.AbstractClinical/methodical issueThe aim of molecular imaging is to visualize and quantify biological, physiological and pathological processes at cellular and molecular levels. Molecular imaging using various techniques has recently become established in breast imaging.Standard radiological methodsCurrently molecular imaging techniques comprise multiparametric magnetic resonance imaging (MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), proton MR spectroscopy (1H-MRSI), nuclear imaging by breast-specific gamma imaging (BSGI), positron emission tomography (PET) and positron emission mammography (PEM) and combinations of techniques (e.g. PET-CT and multiparametric PET-MRI).Methodical innovationsRecently, novel techniques for molecular imaging of breast tumors, such as sodium imaging (23Na-MRI), phosphorus spectroscopy (31P-MRSI) and hyperpolarized MRI as well as specific radiotracers have been developed and are currently under investigation.Practical recommendationsIt can be expected that molecular imaging of breast tumors will enable a simultaneous assessment of the multiple metabolic and molecular processes involved in cancer development and thus an improved detection, characterization, staging and monitoring of response to treatment will become possible.

Influence of fat-water separation and spatial resolution on automated volumetric MRI measurements of fibroglandular breast tissue.

The aim of this study was to investigate the influence of fat–water separation and spatial resolution in MRI on the results of automated quantitative measurements of fibroglandular breast tissue (FGT). Ten healthy volunteers (age range, 28–71 years; mean, 39.9 years) were included in this Institutional Review Board‐approved prospective study. All measurements were performed on a 1.5‐T scanner (Siemens, AvantoFit) using an 18‐channel breast coil. The protocols included isotropic (Di) [TR/TE1/TE2 = 6.00 ms/2.45 ms/2.67 ms; flip angle, 6.0°; 256 slices; matrix, 360 × 360; 1 mm isotropic; field of view, 360°; acquisition time (TA) = 3 min 38 s] and anisotropic (Da) (TR/TE1/TE2 = 10.00 ms/2.39 ms/4.77 ms; flip angle, 24.9°; 80 slices; matrix 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 1 min 25 s) T1 three‐dimensional (3D) fast low‐angle shot (FLASH) Dixon sequences, and a T1 3D FLASH sequence with the same resolution (T1) without (TR/TE = 11.00 ms/4.76 ms; flip angle, 25.0°; 80 slices; matrix, 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 50 s) and with (TR/TE = 29.00 ms/4.76 ms; flip angle, 25.0°; 80 slices; matrix, 360 × 360; voxel size, 0.7 × 0.7 × 2.0 mm3; field of view, 360°; TA = 2 min 35 s) fat saturation. Repeating volunteer measurements after 20 min and repositioning were used to assess reproducibility. An automated and quantitative volumetric breast density measurement system was used for FGT calculation. FGT with Di, Da and T1 measured 4.6–63.0% (mean, 30.6%), 3.2–65.3% (mean, 32.5%) and 1.7–66.5% (mean, 33.7%), respectively. The highest correlation between different MRI sequences was found with the Di and Da sequences (R2 = 0.976). Coefficients of variation (CVs) for FGT calculation were higher in T1 (CV = 21.5%) compared with Dixon (Di, CV = 5.1%; Da, CV = 4.2%) sequences. Dixon‐type sequences worked well for FGT measurements, even at lower resolution, whereas the conventional T1‐weighted sequence was more sensitive to decreasing resolution. The Dixon fat–water separation technique showed superior repeatability of FGT measurements compared with conventional sequences. A standard dynamic protocol using Dixon fat–water separation is best suited for combined diagnostic purposes and prognostic measurements of FGT. Copyright