Simona Padula

Contrast-Enhanced MR Mammography: Improved Lesion Detection and Differentiation with Gadobenate Dimeglumine

OBJECTIVE The objective of our study was to intraindividually compare 0.1 mmol/kg doses of gadobenate dimeglumine and gadopentetate dimeglumine for contrast-enhanced breast MRI. SUBJECTS AND METHODS Forty-seven women (mean age +/- SD, 50.8 +/- 12.9 years) with breast lesions classified as BI-RADS category 3, 4, or 5 for suspicion of malignancy underwent two identical MR examinations at 1.5 T separated by 48-72 hours. T1-weighted gradient-echo images were acquired before contrast administration and at 2-minute intervals after the randomized injection of gadopentetate dimeglumine or gadobenate dimeglumine at 2 mL/s. Two blinded readers evaluated randomized image sets for lesion detection and differentiation as benign or malignant compared with histology. The McNemar exact test and the generalized estimating equation (GEE) were used to compare lesion detection rates and diagnostic performance in terms of sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV). RESULTS Histopathology data were available for 78 lesions. Significantly more lesions overall (75/78 [96%] vs 62/78 [79%], respectively; p = 0.0002) and significantly more malignant lesions (49/50 [98%] vs 38/50 [76%]; p = 0.0009) were detected with gadobenate dimeglumine than gadopentetate dimeglumine. All detected malignant lesions were correctly diagnosed with both agents. More detected benign lesions were correctly diagnosed with gadobenate dimeglumine than with gadopentetate dimeglumine (20/26 [77%] vs 17/24 [71%], respectively). Differentiation of lesions was significantly (p = 0.0001) better with gadobenate dimeglumine. Significantly better diagnostic performance was noted with gadobenate dimeglumine than with gadopentetate dimeglumine, respectively, for sensitivity (98.0% vs 76.0%; p = 0.0064), accuracy (88.5% vs 69.2%; p = 0.0004), PPV (86.0% vs 76.0%; p = 0.0321), and NPV (95.2% vs 57.1%; p = 0.0003). CONCLUSION Lesion detection and malignant-benign differentiation is significantly better with 0.1 mmol/kg gadobenate dimeglumine than 0.1 mmol/kg gadopentetate dimeglumine.

Contrast-enhanced magnetic resonance mammography: does it affect surgical decision-making in patients with breast cancer?

BackgroundDiagnostic imaging in women with suspected breast cancer should accurately detect and diagnose malignant tumors and facilitate the correct choice of therapy. Contrast-enhanced magnetic resonance mammography (CE-MRM) is potentially the imaging modality of choice for accurate patient management decisions.MethodsA total of 164 women with suspected breast cancer based on clinical examination, conventional mammography and/or ultrasound each underwent preoperative bilateral CE-MRM using an axial 3D dynamic T1-weighted gradient-echo sequence and gadobenate dimeglumine as contrast agent. Images were evaluated by two readers in consensus. Histological evaluation of detected lesions was performed on samples from core biopsy or surgery. Determinations were made of the sensitivity, accuracy and positive predictive value of CE-MRM compared to mammography/ultrasound for the detection of malignant lesions and of the impact of CE-MRM for surgical decision-making.FindingsConventional mammography/ultrasound detected 175 lesions in the 164 evaluated patients. CE-MRM revealed 51 additional lesions in 34/164 patients; multifocal and multicentric cancer was detected in 7 and 4 additional patients, respectively, contralateral foci in 21 additional patients and pectoral muscle infiltration in 2 additional patients. CE-MRM also confirmed the absence or benignity of 3 and 1 lesions suspected of malignancy on mammography/ultrasound. The sensitivity and accuracy for malignant lesion detection and identification was 100% and 93.4%, respectively, for CE-MRM compared to 77.3% and 72.1% for mammography/ultrasound, respectively. Patient management was altered for 32/164 (19.5%) patients as a result of CE-MRM.InterpretationCE-MRM positively impacts patient management decisions and should be performed in all women with suspected breast cancer based on clinical examination, mammography and/or ultrasound.

Color-coded automated signal intensity curves for detection and characterization of breast lesions: preliminary evaluation of a new software package for integrated magnetic resonance-based breast imaging.

Objectives:The objective of this study was to evaluate the value of a color-coded automated signal intensity curve software package for contrast-enhanced magnetic resonance mammography (CE-MRM) in patients with suspected breast cancer. Materials and Methods:Thirty-six women with suspected breast cancer based on mammographic and sonographic examinations were preoperatively evaluated on CE-MRM. CE-MRM was performed on a 1.5-T magnet using a 2D Flash dynamic T1-weighted sequence. A dosage of 0.1 mmol/kg of Gd-BOPTA was administered at a flow rate of 2 mL/s followed by 10 mL of saline. Images were analyzed with the new software package and separately with a standard display method. Statistical comparison was performed of the confidence for lesion detection and characterization with the 2 methods and of the diagnostic accuracy for characterization compared with histopathologic findings. Results:At pathology, 54 malignant lesions and 14 benign lesions were evaluated. All 68 (100%) lesions were detected with both methods and good correlation with histopathologic specimens was obtained. Confidence for both detection and characterization was significantly (P ≤ 0.025) better with the color-coded method, although no difference (P > 0.05) between the methods was noted in terms of the sensitivity, specificity, and overall accuracy for lesion characterization. Excellent agreement between the 2 methods was noted for both the determination of lesion size (kappa = 0.77) and determination of SI/T curves (kappa = 0.85). Conclusions:The novel color-coded signal intensity curve software allows lesions to be visualized as false color maps that correspond to conventional signal intensity time curves. Detection and characterization of breast lesions with this method is quick and easily interpretable.

Color Doppler Ultrasound in Renal Transplant: Role of Resistive Index versus Renal Cortical Ratio in the Evaluation of Renal Transplant Diseases

Background/Aims: Ultrasound (US) and color Doppler are not sensitive enough to detect anomalies in cortical perfusion, which is affected in most graft dysfunctions. The renal cortical ratio (RCR) is a variation in the resistive index (RI) values from the renal artery to cortical vessels, expressed in percent. The aim of this study was to compare the RI and RCR in the differentiation of normal and pathological grafts, to assess the positive predictive value of RCR and show that RCR enables earlier diagnosis than RI. Methods: Based on clinical, biochemical and histological examinations, 494 renal allografts were divided into 3 groups (normal grafts, acute and chronic pathologies). All patients underwent US color Doppler. RI was measured and RCR calculated. Follow-up confirmed the initial division in groups. Statistical significance was calculated using the two-tailed Student’s t test. The positive predictive value was calculated for each group. Results: 24 h after transplant, RCR differentiated normal grafts from acute dysfunctions despite confusing biochemical values and clinical symptoms. In chronic patients, RCR variations occurred later but always before the serum creatinine level increased. Conclusion: RCR presented a higher positive predictive value than RI. RCR curves were already altered in the early stages of transplant pathologies. RCR calculation is easy and makes a significant contribution towards a correct early diagnosis.

Detection and Characterization of Breast Lesions: Color-coded Signal Intensity Curve Software for Magnetic Resonance-based Breast Imaging

Publisher Summary This chapter explores several innovative techniques employed in the study of breast cancer. One of the technologies, contrast-enhanced magnetic resonance (MR) mammography (CE-MRM) can help to distinguish between benign and malignant lesions on the basis of lesion morphology and in most cases through the profile of the curve for lesion signal intensity enhancement over time (SI/T curve). Magnetic resonance (MR) images acquired with high spatial resolution are needed for accurate assessment of the morphologic characteristics and internal architecture of lesions, while fast imaging protocols with high temporal resolution are needed to evaluate the enhancement kinetics of lesions. Two principal strategies have evolved to improve specificity: rapid dynamic imaging after gadolinium enhancement and high spatial resolution imaging. CE- magnetic resonance imaging (MRI), besides detecting morphological information of the lesion, can provide dynamic information on the contrast medium behavior related to the intensity of MRI signal over time. The signal intensity-time curves of malignant lesions have characteristic washout profiles, whereas the curves of benign lesions more frequently have a steady increase or plateau profile. A digital imaging and communication in medicine (DICOM)-compatible software package is developed, which is able to automatically load a complete breast MRI study and to automatically register and subtract images before creating a false color map (FCM) for each scan plane. The approach compares the qualitative parameters of the signal intensity enhancement over time (SI/T) evolution of each point with the standard lesion curve types and modulates the color brightness with the earliness of the enhancement peak. This qualitative approach to lesion classification greatly reduces the computational effort and the time required for examination analysis even on an individual PC-based system.