Contrast-enhanced spectral mammography vs. mammography and MRI - clinical performance in a multi-reader evaluation.

OBJECTIVES: To compare the diagnostic performance of contrast-enhanced spectral mammography (CESM) to digital mammography (MG) and magnetic resonance imaging (MRI) in a prospective two-centre, multi-reader study. METHODS: One hundred seventy-eight women (mean age 53 years) with invasive breast cancer and/or DCIS were included after ethics board approval. MG, CESM and CESM + MG were evaluated by three blinded radiologists based on amended ACR BI-RADS criteria. MRI was assessed by another group of three readers. Receiver-operating characteristic (ROC) curves were compared. Size measurements for the 70 lesions detected by all readers in each modality were correlated with pathology. RESULTS: Reading results for 604 lesions were available (273 malignant, 4 high-risk, 327 benign). The area under the ROC curve was significantly larger for CESM alone (0.84) and CESM + MG (0.83) compared to MG (0.76) (largest advantage in dense breasts) while it was not significantly different from MRI (0.85). Pearson correlation coefficients for size comparison were 0.61 for MG, 0.69 for CESM, 0.70 for CESM + MG and 0.79 for MRI. CONCLUSIONS: This study showed that CESM, alone and in combination with MG, is as accurate as MRI but is superior to MG for lesion detection. Patients with dense breasts benefitted most from CESM with the smallest additional dose compared to MG. KEY POINTS: • CESM has comparable diagnostic performance (ROC-AUC) to MRI for breast cancer diagnostics. • CESM in combination with MG does not improve diagnostic performance. • CESM has lower sensitivity but higher specificity than MRI. • Sensitivity differences are more pronounced in dense and not significant in non-dense breasts. • CESM and MRI are significantly superior to MG, particularly in dense breasts.

Intraindividual comparison of two methods of volumetric breast composition assessment.

RATIONALE AND OBJECTIVES: To compare the results of two software-based methods, Quantra and Volpara, for volumetric breast composition assessment. MATERIALS AND METHODS: Four hundred forty-five normal, bilateral, two-view, digital mammograms were included. Breast volume (BV), fibroglandular tissue volume (FTV), and percent density (PD) were measured using both methods and compared. Deming regression was performed to obtain linear equations for mapping the results of one software on the other. RESULTS: The median and quartile ranges of both methods agreed well for BV but were different for FTV and PD, with Quantra showing much higher values of FTV and PD. The correlation of results obtained by both methods for BV, FTV, and PD was 0.99, 0.91, and 0.94, respectively. Intraclass correlation in the assignment of quartiles of BV, FTV, and PD was 0.96, 0.86, and 0.90, respectively. Both methods showed a similar association of FTV and PD with patient age and similar left-to-right correlation. Mapping of results onto each other using linear equations removed the systematic differences. CONCLUSIONS: Although Quantra and Volpara use different models for analysis of volumetric breast composition and produce different nominal results of FTV and PD, both methods are highly correlated and show very good to excellent agreement in quartile assignment of all parameters measured. Both methods show a similar association with patient age and similar reproducibility. Both methods can be mapped onto each other using the equations suggested.

Intraindividual, randomized comparison of the macrocyclic contrast agents gadobutrol and gadoterate meglumine in breast magnetic resonance imaging.

OBJECTIVES: To compare intraindividually two macrocyclic contrast agents - gadobutrol and gadoterate meglumine (Gd-DOTA) - for dynamic and quantitative assessment of relative enhancement (RE) in benign and malignant breast lesions. METHODS: This was an ethically approved, prospective, single-centre, randomized, crossover study in 52 women with suspected breast lesions referred for magnetic resonance imaging (MRI). Each patient underwent one examination with gadobutrol and one with Gd-DOTA (0.1 mmol/kg BW) on a 1.5 T system 1 - 7 days apart. Dynamic, T1-weighted, 3D gradient echo sequences were acquired under identical conditions. Quantitative evaluation with at least three regions of interest (ROI) per lesion was performed. Primary endpoint was RE during the initial postcontrast phase after the first and second dynamic acquisition, and peak RE. All lesions were histologically proven; differences between the examinations were evaluated. RESULTS: Forty-five patients with a total of 11 benign and 34 malignant lesions were assessed. Mean RE was significantly higher for gadobutrol than Gd-DOTA (p < 0.0001). Gadobutrol showed significantly less washout (64.4 %) than Gd-DOTA (75.4 %) in malignant lesions (p = 0.048) CONCLUSIONS: Gadobutrol has higher RE values compared with Gd-DOTA, whereas Gd-DOTA shows more marked washout in malignant lesions. This might improve the detection of breast lesions and influence the specificity of breast MRI-imaging.

Contrast-enhanced spectral mammography: Does mammography provide additional clinical benefits or can some radiation exposure be avoided?

The purpose of this study was to compare contrast-enhanced spectral mammography (CESM) with mammography (MG) and combined CESM + MG in terms of detection and size estimation of histologically proven breast cancers in order to assess the potential to reduce radiation exposure. A total of 118 patients underwent MG and CESM and had final histological results. CESM was performed as a bilateral examination starting 2 min after injection of iodinated contrast medium. Three independent blinded radiologists read the CESM, MG, and CESM + MG images with an interval of at least 4 weeks to avoid case memorization. Sensitivity and size measurement correlation and differences were calculated, average glandular dose (AGD) levels were compared, and breast densities were reported. Fisher's exact and Wilcoxon tests were performed. A total of 107 imaging pairs were available for analysis. Densities were ACR1: 2, ACR2: 45, ACR3: 42, and ACR4: 18. Mean AGD was 1.89 mGy for CESM alone, 1.78 mGy for MG, and 3.67 mGy for the combination. In very dense breasts, AGD of CESM was significantly lower than MG. Sensitivity across readers was 77.9 % for MG alone, 94.7 % for CESM, and 95 % for CESM + MG. Average tumor size measurement error compared to postsurgical pathology was -0.6 mm for MG, +0.6 mm for CESM, and +4.5 mm for CESM + MG (p < 0.001 for CESM + MG vs. both modalities). CESM alone has the same sensitivity and better size assessment as CESM + MG and was significantly better than MG with only 6.2 % increase in AGD. The combination of CESM + MG led to systematic size overestimation. When a CESM examination is planned, additional MG can be avoided, with the possibility of saving up to 61 % of radiation dose, especially in patients with dense breasts.

Volumetric breast composition analysis: reproducibility of breast percent density and fibroglandular tissue volume measurements in serial mammograms.

BACKGROUND: Volumetric breast composition analysis represents a useful tool for assessing changes in breast composition over time. However, no data exist on the reproducibility of this method in serial mammograms. PURPOSE: To assess the reproducibility of two volumetric breast composition parameters, breast percent density (PD) and fibroglandular tissue volume (FTV), in consecutive mammograms. MATERIAL AND METHODS: Volumetric breast composition analysis to determine PD and FTV was performed in two consecutive unilateral mammograms of 211 patients. All mammograms were obtained on the same digital mammography unit within a maximum interval of 24 months. Volumetric data for analysis for both examinations were available for 174 patients. Thirty-two patients had successful volumetric analysis of additional consecutive examinations on a second digital mammography unit. Inter-examination correlation of measurements and absolute differences were analyzed. Bland-Altman analysis was performed to compare readings from different mammography units. RESULTS: Mean FTV remained constant over the study period. A reduction in PD of 0.5% and a mean increase in breast volume (BV) of 3% were observed. FTV measurements obtained on the same mammography unit were significantly more reproducible than PD measurements (Pearson correlation coefficients of 0.947 and 0.920, respectively; P < 0.05). A 15% difference between mean absolute volume measurements (FTV and BV) obtained on different mammography units was observed (P ≤ 0.001), while mean PD was close to the expected value. CONCLUSION: Volumetric breast composition analysis is highly reproducible in serial mammograms in normal women. FTV is a more reproducible parameter than PD, indicating that absolute quantification of breast parenchyma may be preferable to the measurement of relative parameters such as PD. However, a disadvantage of using FTV is that it is susceptible to systematic differences when measurements are obtained on different imaging platforms.

Assessment of fatty degeneration of the gluteal muscles in patients with THA using MRI: reliability and accuracy of the Goutallier and quartile classification systems.

The purpose of this study was to quantify the performance of the Goutallier classification for assessing fatty degeneration of the gluteus muscles from magnetic resonance (MR) images and to compare its performance to a newly proposed system. Eighty-four hips with clinical signs of gluteal insufficiency and 50 hips from asymptomatic controls were analyzed using a standard classification system (Goutallier) and a new scoring system (Quartile). Interobserver reliability and intraobserver repeatability were determined, and accuracy was assessed by comparing readers' scores with quantitative estimates of the proportion of intramuscular fat based on MR signal intensities (gold standard). The existing Goutallier classification system and the new Quartile system performed equally well in assessing fatty degeneration of the gluteus muscles, both showing excellent levels of interrater and intrarater agreement. While the Goutallier classification system has the advantage of being widely known, the benefit of the Quartile system is that it is based on more clearly defined grades of fatty degeneration.

Response to neoadjuvant treatment of invasive ductal breast carcinomas including outcome evaluation: MRI analysis by an automatic CAD system in comparison to visual evaluation.

BACKGROUND: The aim of this study was to evaluate imaging-based response to standardized neoadjuvant chemotherapy (NACT) regimen by dynamic contrast-enhanced magnetic resonance mammography (DCE-MRM), whereas MR images were analyzed by an automatic computer-assisted diagnosis (CAD) system in comparison to visual evaluation. MRI findings were correlated with histopathologic response to NACT and also with the occurrence of metastases in a follow-up analysis. PATIENTS AND METHODS: Fifty-four patients with invasive ductal breast carcinomas received two identical MRI examinations (before and after NACT; 1.5T, contrast medium gadoteric acid). Pre-therapeutic images were compared with post-therapeutic examinations by CAD and two blinded human observers, considering morphologic and dynamic MRI parameters as well as tumor size measurements. Imaging-assessed response to NACT was compared with histopathologically verified response. All clinical, histopathologic, and DCE-MRM parameters were correlated with the occurrence of distant metastases. RESULTS: Initial and post-initial dynamic parameters significantly changed between pre- and post-therapeutic DCE-MRM. Visually evaluated DCE-MRM revealed sensitivity of 85.7%, specificity of 91.7%, and diagnostic accuracy of 87.0% in evaluating the response to NACT compared to histopathology. CAD analysis led to more false-negative findings (37.0%) compared to visual evaluation (11.1%), resulting in sensitivity of 52.4%, specificity of 100.0%, and diagnostic accuracy of 63.0%. The following dynamic MRI parameters showed significant associations to occurring metastases: Post-initial curve type before NACT (entire lesions, calculated by CAD) and post-initial curve type of the most enhancing tumor parts after NACT (calculated by CAD and manually). CONCLUSIONS: In the accurate evaluation of response to neoadjuvant treatment, CAD systems can provide useful additional information due to the high specificity; however, they cannot replace visual imaging evaluation. Besides traditional prognostic factors, contrast medium-induced dynamic MRI parameters reveal significant associations to patient outcome, i.e. occurrence of distant metastases.

Volume matters: CT-based renal cortex volume measurement in the evaluation of living kidney donors.

Currently, no international standard for the pre-transplant evaluation of living donor renal function exists. Following a standardized questionnaire on current practice in all Eurotransplant (ET) centers, we compared a new CT-based technique to measure renal cortex volume with our standard of DTPA-clearance combined with MAG3-scintigraphy (DTPA × MAG3) and with creatinine-based methods in 167 consecutive living kidney donors. Most ET centers use creatinine-clearance (64%) to measure total renal function and radioistopic methods (82%) to assess split renal function. Before transplantation, CT-measured total cortex volume (r = 0.67; P < 0.001) and estimated GFR using the Cockcroft-Gault formula [eGFR(CG)] (r = 0.55; P < 0.001) showed the strongest correlation with DTPA-clearance. In contrast, the correlation between DTPA-clearance and creatinine clearance was weak (r = 0.21; P = 0.02). A strong correlation was observed between CT-measured split cortex volume and MAG3-measured split renal function (r = 0.93; P < 0.001). A strong correlation was also found between pre-transplant split renal function assessed by eGFR(CG) together with cortex volume measurement and post-transplant eGFR(CG) of both, the donor (r = 0.83; P < 0.001) and the recipient (r = 0.75; P < 0.001). In conclusion CT-based assessment of renal cortex volume bears the potential to substitute existing methods to assess pre-transplant living donor split renal function.

Factors affecting the rate of false positive marks in CAD in full-field digital mammography.

OBJECTIVE: To assess the effect of breast density, fibroglandular tissue volume, and breast volume on the rate of false-positive marks of a computer-assisted detection software in digital mammography. MATERIALS AND METHODS: 222 patients with normal digital mammograms and a minimum follow-up of 22 months were retrospectively identified. MLO and CC views were analyzed using a CAD software with three operating points ('specific', 'balanced', 'sensitive'). False-positive marks were recorded. Images were analyzed by a volumetric breast density assessment software, yielding estimates of percentage density, fibroglandular tissue volume, and breast volume. Statistical analysis was performed using the Mann-Whitney U-test, the t-test for independent samples and the Poisson regression model. RESULTS: Patients with high fibroglandular tissue volumes had a higher mean number of false-positive mass marks than patients with low fibroglandular tissue volumes (specific setting: 0.50 vs. 0.35, respectively; balanced setting: 0.70 vs. 0.40, respectively, p<0.05; sensitive setting: 0.89 vs. 0.58, respectively, p<0.05). Relative risk for a false-positive mass marker increased by 1.43 (p<0.05), 1.63 (p<0.001) and 1.50 (p<0.01) per 100ml of fibroglandular tissue for the specific, balanced and sensitive settings, respectively. No significant effects of percentage density or breast volume on the number or the relative risk of false-positive mass marks were observed. CONCLUSION: The volume of fibroglandular tissue present, but not the percentage density of the breast, affected the specificity for masses of the CAD software investigated. This may have implications for improving the performance of CAD systems, as the specificity of CAD may be improved by adjusting the algorithm threshold depending on the volume of fibroglandular tissue present. Considering both factors, fibroglandular tissue volume and percentage density, independently, could improve overall CAD performance in subgroups of patients, e.g. those with small, dense breasts or large breasts with low density.

Evaluation of tomosynthesis elastography in a breast-mimicking phantom.

OBJECTIVE: To evaluate whether measurement of strain under static compression in tomosynthesis of a breast-mimicking phantom can be used to distinguish tumor-simulating lesions of different elasticities and to compare the results to values predicted by rheometric analysis as well as results of ultrasound elastography. MATERIALS AND METHODS: We prepared three soft breast-mimicking phantoms containing simulated tumors of different elasticities. The phantoms were imaged using a wide angle tomosynthesis system with increasing compression settings ranging from 0 N to 105 N in steps of 15 N. Strain of the inclusions was measured in two planes using a commercially available mammography workstation. The elasticity of the phantom matrix and inclusion material was determined by rheometric analysis. Ultrasound elastography of the inclusions was performed using two different ultrasound elastography algorithms. RESULTS: Strain at maximal compression was 24.4%/24.5% in plane 1/plane 2, respectively, for the soft inclusion, 19.6%/16.9% for the intermediate inclusion, and 6.0%/10.2% for the firm inclusion. The strain ratios predicted by rheometrical testing were 0.41, 0.83 and 1.26 for the soft, intermediate, and firm inclusions, respectively. The strain ratios obtained for the soft, intermediate, and firm inclusions were 0.72±0.13, 1.02±0.21 and 2.67±1.70, respectively for tomosynthesis elastography, 0.91, 1.64 and 2.07, respectively, for ultrasound tissue strain imaging, and 0.97, 2.06 and 2.37, respectively, for ultrasound real-time elastography. CONCLUSIONS: Differentiation of tumor-simulating inclusions by elasticity in a breast mimicking phantom may be possible by measuring strain in tomosynthesis. This method may be useful for assessing elasticity of breast lesions tomosynthesis of the breast.

Development of low-dose photon-counting contrast-enhanced tomosynthesis with spectral imaging.

PURPOSE: To demonstrate the feasibility of low-dose photon-counting tomosynthesis in combination with a contrast agent (contrast material-enhanced tomographic mammography) for the differentiation of breast cancer. MATERIALS AND METHODS: All studies were approved by the institutional review board, and all patients provided written informed consent. A phantom model with wells of iodinated contrast material (3 mg of iodine per milliliter) 1, 2, 5, 10, and 15 mm in diameter was assessed. Nine patients with malignant lesions and one with a high-risk lesion (atypical papilloma) were included (all women; mean age, 60.7 years). A multislit photon-counting tomosynthesis system was utilized (spectral imaging) to produce both low- and high-energy tomographic data (below and above the k edge of iodine, respectively) in a single scan, which allowed for dual-energy visualization of iodine. Images were obtained prior to contrast material administration and 120 and 480 seconds after contrast material administration. Four readers independently assessed the images along with conventional mammograms, ultrasonographic images, and magnetic resonance images. Glandular dose was estimated. RESULTS: Contrast agent was visible in the phantom model with simulated spherical tumor diameters as small as 5 mm. The average glandular dose was measured as 0.42 mGy per complete spectral imaging tomosynthesis scan of one breast. Because there were three time points (prior to contrast medium administration and 120 and 480 seconds after contrast medium administration), this resulted in a total dose of 1.26 mGy for the whole procedure in the breast with the abnormality. Seven of 10 cases were categorized as Breast Imaging Reporting and Data System score of 4 or higher by all four readers when reviewing spectral images in combination with mammograms. One lesion near the chest wall was not captured on the spectral image because of a positioning problem. CONCLUSION: The use of contrast-enhanced tomographic mammography has been demonstrated successfully in patients with promising diagnostic benefit. Further studies are necessary to fully assess diagnostic sensitivity and specificity.

Breast cancer: early- and late-fluorescence near-infrared imaging with indocyanine green--a preliminary study.

PURPOSE: To assess early- and late-fluorescence near-infrared imaging, corresponding to the vascular (early-fluorescence) and extravascular (late-fluorescence) phases of indocyanine green (ICG) enhancement, for breast cancer detection and benign versus malignant breast lesion differentiation. MATERIALS AND METHODS: The study was approved by the ethical review board; all participants provided written informed consent. Twenty women with 21 breast lesions were examined with near-infrared imaging before, during, and after intravenous injection of ICG. Absorption and fluorescence projection mammograms were recorded simultaneously on a prototype near-infrared imaging unit. Two blinded readers independently assessed the images and assigned visibility scores to lesions seen on the absorption and absorption-corrected fluorescence mammograms. Imaging results were compared with histopathologic findings. Lesion contrast and diameter on the fluorescence mammograms were measured, and Cohen κ, Mann-Whitney U, and Spearman ρ tests were conducted. RESULTS: The absorption-corrected fluorescence ratio mammograms showed high contrast (contrast value range, 0.25-0.64) between tumors and surrounding breast tissue. Malignant lesions were correctly defined in 11 (reader 1) and 12 (reader 2) of 13 cases, and benign lesions were correctly defined in six (reader 1) and five (reader 2) of eight cases with late-fluorescence imaging. Lesion visibility scores for malignant and benign lesions were significantly different on the fluorescence ratio mammograms (P = .003) but not on the absorption mammograms (P = .206). Mean sensitivity and specificity reached 92% ± 8 (standard error of mean) and 75% ± 16, respectively, for fluorescence ratio imaging compared with 100% ± 0 and 25% ± 16, respectively, for conventional mammography alone. CONCLUSION: Preliminary data suggest that early- and late-fluorescence ratio imaging after ICG administration can be used to distinguish malignant from benign breast lesions.

Intra-individual comparison of average glandular dose of two digital mammography units using different anode/filter combinations.

RATIONALE AND OBJECTIVES: The aim of this study was to compare average glandular dose (AGD) in two full-field digital mammography units using different anode/filter combinations. MATERIALS AND METHODS: Mammographies of 50 consecutive patients on a mammography system using a tungsten/rhodium (W/Rh) anode/filter combination were retrospectively compared to prior examinations on a different mammography unit using combinations of Molybdenum (Mo) and Rhodium (Rh). To exclude effects of increasing patient age, two prior examinations within 5 years were used. Both views of one breast were chosen for analysis. AGD was recorded as stated by each mammography unit. Accuracy of stated AGD and contrast-detail resolution were assessed using different breast phantoms. RESULTS: The mean AGDs from the examinations using W/Rh were 0.95 mGy and 1.01 mGy for craniocaudal (CC) and mediolateral oblique (MLO) views compared to 1.51 mGy and 1.54 mGy, respectively, using combinations of Mo and Rh (P < .001). Relative reduction of AGD was independent of breast thickness but decreased with increasing breast density (partial correlation coefficient of 0.46, P < .005 and 0.57, P < .001, for CC and MLO views, respectively). Low-level contrast resolution was equal in both units using standard acquisition parameters. CONCLUSION: In clinical mammographies, higher energy beam spectra obtained using W/Rh anode/filter combinations may significantly contribute to lowering AGD compared to Mo/Mo, Mo/Rh, and Rh/Rh in breasts that are not extremely dense.

Determining optimal acquisition parameters for computed tomography coronary angiography: evaluation of a software-assisted, breathhold exam simulation.

RATIONALE AND OBJECTIVES: Scanning parameters used in multislice computed tomographic (MSCT) coronary angiography should be adapted to patients' heart rates. The aim of this study was to evaluate the rate of success of a software-assisted scan simulation to determine optimal gantry rotation time prior to MSCT coronary angiography. MATERIALS AND METHODS: Data from 218 64-slice MSCT coronary angiographic studies were retrospectively analyzed. Prior to the MSCT examination, a scan had been simulated by giving a breath-hold command, after which a software program recorded the patient's heart rate from an electrocardiogram over the expected scanning time and predicted optimal scanning parameters. The success rate in predicting optimal parameters for the subsequent MSCT examination and the resulting acquisition window width were analyzed. RESULTS: There was a wide range of heart rates among the patients. The mean intraindividual variation during scan simulation and examination was 4.8 beats/min. Optimal scan parameters were selected in 179 of 218 cases (82%). The median acquisition window width achieved in this group was 174 ms (range, 100-200), compared with 192 ms (range, 149-225) in cases in which suboptimal settings were selected (P < .001). Correct prediction occurred significantly more often in patients with low heart rates (<66 beats/min) than in those with higher heart rates (>or=66 beats/min) (93% vs 66%; P < .001). CONCLUSIONS: The software-assisted scan simulation was a fast and simple procedure that allowed the selection of optimal computed tomographic parameters in >80% of patients. The procedure may be a useful adjunct to avoid unwanted synchronicity of gantry rotation and heart cycle and optimize temporal resolution in MSCT coronary angiography.

Multi-detector CT in peritoneal carcinomatosis: diagnostic role of thin slices and multiplanar reconstructions.

BACKGROUND: In order to investigate whether 1-mm thin slices and multiplanar reconstructions (MPRs) of multi-detector computed tomography (CT) datasets interpreted in addition to isotropic 5-mm thick slices in one session improve the detection of peritoneal carcinomatosis. METHODS: The abdominal CT datasets of 44 patients with histologically proven tumors of the abdomen or pelvis were retrospectively evaluated for peritoneal carcinomatosis by four radiologists with variable experience (radiologist 1: >or=10 years, radiologists 2 and 3: 1.5 years, radiologist 4: 0.5 years). In three successive steps, the radiologists evaluated first the axial 5-mm slices, second the 1-mm slices, and third the MPRs and rated their diagnostic confidence. RESULTS: Specificity was nearly unchanged for all the four radiologists. Sensitivity improved for the most experienced and the least experienced radiologists and was unchanged for the two readers with intermediate skills. Except for the third step of radiologist 4, no statistically significant differences in diagnostic performance were detected. The diagnostic confidence of all the four readers benefited to variable degrees from interpretation of the 1-mm slices and MPRs. CONCLUSIONS: While 5-mm slices are sufficient for the detection of peritoneal carcinomatosis, 1-mm slices and MPRs can improve sensitivity and diagnostic confidence.