Abdominal CT: a radiologist-driven adjustment of the dose of iodinated contrast agent approaches a calculation per lean body weight

BACKGROUND: The contrast agent (CA) dose for abdominal computed tomography (CT) is typically based on patient total body weight (TBW), ignoring adipose tissue distribution. We report on our experience of dosing according to the lean body weight (LBW). METHODS: After Ethics Committee approval, we retrospectively screened 219 consecutive patients, 18 being excluded for not matching the inclusion criteria. Thus, 201 were analysed (106 males), all undergoing a contrast-enhanced abdominal CT with iopamidol (370 mgI/mL) or iomeprol (400 mgI/mL). LBW was estimated using validated formulas. Liver contrast-enhancement (CEL) was measured. Data were reported as mean\u2009\ub1\u2009standard deviation. Pearson correlation coefficient, ANOVA, and the Levene test were used. RESULTS: Mean age was 66\u2009\ub1\u200913 years, TBW 72\u2009\ub1\u200915 kg, LBW 53\u2009\ub1\u200911 kg, and LBW/TBW ratio 74\u2009\ub1\u20098%; body mass index was 26\u2009\ub1\u20095 kg/m2, with 9 underweight patients (4%), 82 normal weight (41%), 76 overweight (38%), and 34 obese (17%). The administered CA dose was 0.46\u2009\ub1\u20090.06 gI/kg of TBW, corresponding to 0.63\u2009\ub1\u20090.09 gI/kg of LBW. A negative correlation was found between TBW and CA dose (r\u2009=\u2009-0.683, p\u2009<\u20090.001). CEL (Hounsfield units) was 51\u2009\ub1\u200918 in underweight patients, 44\u2009\ub1\u20098 in normal weight, 42\u2009\ub1\u20099 in overweight, and 40\u2009\ub1\u20096 in obese, with a significant difference for both mean (p\u2009=\u20090.004) and variance (p\u2009<\u20090.001). A low but significant positive correlation was found between CEL and CA dose in gI per TBW (r\u2009=\u20090.371, p\u2009<\u20090.001) or per LBW (r\u2009=\u20090.333, p\u2009<\u20090.001). CONCLUSIONS: The injected CA dose was highly variable, with obese patients receiving a lower dose than underweight patients, as a radiologist-driven 'compensation effect'. Diagnostic abdomen CT examinations may be obtained using 0.63 gI/kg of LBW

Breast vascular mapping obtained with contrast-enhanced MR imaging : implications for cancer diagnosis, treatment, and risk stratification

The value of breast vascular maps obtained using contrast-enhanced MR imaging has recently been explored. Additional information is obtained only by evaluating maximum intensity projections of the first dynamic subtraction to achieve a form of MR angiography of the breast. No increase in acquisition time and no dedicated contrast injections are needed. Four studies have been performed to evaluate the one-sided (asymmetric) increase in vascularity associated with ipsilateral cancer in a total of 404 patients with a cancer prevalence ranging from 38% to 80%. Sensitivity ranged from 72% to 88%, specificity from 57% to 100%, positive predictive value from 85% to 100%, negative predictive value from 38% to 88%, and overall accuracy from 73% to 87%. An asymmetric increase in breast vascularity ipsilateral to a cancer may be due to reduced flow resistance in the tumour, to a high metabolic rate (more likely in large tumours) or to angiogenic stimulation of the whole breast harbouring the lesion (more likely in small tumours). Tumour size could play a specific role in determining the ipsilaterally increased vascularity, and invasive cancers might be more frequently associated with ipsilaterally increased vascularity than in situ cancers. Moreover, while a reduction in breast vasculature has anecdotically been observed in breasts with locally advanced cancers treated with neoadjuvant chemotherapy, especially when taxanes are used, the higher incidence of breast cancer in patients with size asymmetry between the breasts as determined on screening mammography suggests that a role for breast MR vascular mapping in breast cancer risk stratification should be explored. Finally, arteries and veins might be differentiated with dedicated techniques. High-relaxivity agents may be used with advantage in these future investigations

Response to treatment : the role of imaging

Measurement of solid tumor response to treatment relies mainly on imaging. WHO tumor response criteria and, more recently, RECIST (response evaluation criteria in solid tumors) have provided means to objectively measure tumor response in clinical trials with imaging. These guidelines have been rapidly adopted in clinical practice to monitor patient treatment and for therapy planning. However, relying only on anatomical information is not always sufficient when evaluating new drugs that will reduce a tumor's functionality while preserving its size. Finding more reliable and reproducible measures of tumor response is one of the most important and difficult challenges facing modern radiology as it requires an entirely new approach to imaging. The aim of this book is to address the assessment of response to treatment by adopting a multidisciplinary perspective, just as occurs in real life in a comprehensive cancer center. Oncologists and imaging experts consider two cancer models, locally advanced disease and metastatic disease, jointly exploring both conventional and advanced means of measuring response to standard treatment protocols and new targeted therapie

Dynamic breast magnetic resonance imaging without complications in a patient with dual-chamber demand pacemaker

Mammography and ultrasound indicated a cancer of the right breast in a 77-year-old woman with a dual-chamber demand pacemaker. The patient was not pacemaker-dependent. She underwent breast 1.5T magnetic resonance imaging (MRI) (dynamic gradient echo sequence with Gd-DOTA 0.1 mmol/kg). Before the patient entered the MR room, the configuration of the device was changed (the response to magnet was switched from asynchronous to off and the rate-responsive algorithm was disabled). No relevant modifications of heart rhythm or rate were observed during the MR examination. No symptom was reported. Immediately after the examination, the pacemaker interrogation showed neither program changes nor alert warnings. MRI detected a bifocal cancer in the right breast which allowed tailored breast-conserving treatment to be initiated. Histopathology confirmed a bifocal invasive ductal carcinoma

Gadobenate dimeglumine as a contrast agent for dynamic breast magnetic resonance imaging: effect of higher initial enhancement thresholds on diagnostic performance

RATIONALE AND OBJECTIVE: Gadobenate dimeglumine (Gd-BOPTA), a high-relaxivity contrast agent, has been recently proposed for dynamic MR imaging of the breast. The objective of this study was to optimize the diagnostic performance of Gd-BOPTA-enhanced dynamic breast MR imaging by using adjusted initial enhancement thresholds. METHODS: Thirty-four patients with 36 breast lesions (malignant/benign = 28/8) underwent dynamic breast MRI with 0.1 mmol/kg Gd-BOPTA and 120-second time resolution. A score system based on shape (round/oval/lobular = 0; linear/dendritic/stellate = 1), margins (defined = 0; undefined = 1), pattern (homogeneous = 0; inhomogeneous = 1; rim = 2), kinetics (continuous = 0; plateau = 1; washout = 2), and initial enhancement was used. Initial enhancement was determined with standard (100% = 2) and adjusted (240% = 2) thresholds. Scores of 0 to 3 indicated benign lesions and scores of 4 to 8 malignant lesions. Diagnostic performance was assessed in terms of sensitivity, specificity, positive and negative predictive values, and overall accuracy. RESULTS: The initial enhancement was >100% for 26 malignant and 7 benign lesions and >240% for 16 and 1 lesions, respectively. The overall score was 5.89 \ub1 1.34 with standard thresholds and 5.50 \ub1 1.53 with adjusted thresholds (P = 0.003) for cancers, 4.00 \ub1 1.93 and 3.25 \ub1 1.75 (P = 0.028) for benign lesions, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy was 96%, 13%, 79%, 50%, and 78%, respectively, with standard thresholds and 96%, 75%, 93%, 86%, and 92%, respectively, with adjusted thresholds. A ductal carcinoma in situ was false negative whereas a fat necrosis and a papilloma were false positive with both thresholds. Three fibroadenomas, 1 adenosis, and 1 fibrosis were false positive with standard thresholds but true negatives with adjusted thresholds. CONCLUSIONS: Lesion characterization with Gd-BOPTA requires higher thresholds for initial enhancement than those used with conventional Gd-chelates, leading to improved specificity, predictive values, and accuracy

What is the sensitivity of mammography and dynamic MR imaging for DCIS if the whole-breast histopathology is used as a reference standard?

PURPOSE: Our purpose was to compare mammography and dynamic contrast-enhanced magnetic resonance imaging (MRI) in the detection of ductal carcinoma in situ (DCIS). MATERIALS AND METHODS: Ninety patients (aged 58.6+/-16.1 years) who were candidates for unilateral (n=81) or bilateral (n=9) mastectomy underwent mammography and dynamic contrast-enhanced breast MRI using a coronal three-dimensional gradient-echo sequence with slice thickness or =5 and or =10 and or =20 mm (n=2); not assessed (n=10). Sensitivity was 35% (9/26) for mammography and 38% (10/26) for MRI (not significant difference, McNemar test). Both mammography and MRI provided a true positive result in seven cases (four of them measured at pathology, with a diameter of 20.0+/-12.9 mm; median 20 mm) and a false negative result in 14 cases (10 of them measured at pathology, with a diameter of 4.2+/-1.9 mm; median 4.6 mm) (p=0.024, Mann-Whitney U test). Only 46% (12/26) of DCIS were detected at mammography and/or MRI; the remaining 54% (14/26) were diagnosed only at pathological examination. CONCLUSIONS: When the whole breast is used as the histopathological reference standard, both mammography and MRI show low sensitivity for DCIS

Lean body weight versus total body weight to calculate the iodinated contrast media volume in abdominal CT : a randomised controlled trial

Objectives: Iodinated contrast media (ICM) could be more appropriately dosed on patient lean body weight (LBW) than on total body weight (TBW). Methods: After Ethics Committee approval, trial registration NCT03384979, patients aged 65 18 years scheduled for multiphasic abdominal CT were randomised for ICM dose to LBW group (0.63 gI/kg of LBW) or TBW group (0.44 gI/kg of TBW). Abdominal 64-row CT was performed using 120 kVp, 100-200 mAs, rotation time 0.5 s, pitch 1, Iopamidol (370 mgI/mL), and flow rate 3 mL/s. Levene, Mann-Whitney U, and \u3c72 tests were used. The primary endpoint was liver contrast enhancement (LCE). Results: Of 335 enrolled patients, 17 were screening failures; 44 dropped out after randomisation; 274 patients were analysed (133 LBW group, 141 TBW group). The median age of LBW group (66 years) was slightly lower than that of TBW group (70 years). Although the median ICM-injected volume was comparable between groups, its variability was larger in the former (interquartile range 27 mL versus 21 mL, p = 0.01). The same was for unenhanced liver density (IQR 10 versus 7 HU) (p = 0.02). Median LCE was 40 (35-46) HU in the LBW group and 40 (35-44) HU in the TBW group, without significant difference for median (p = 0.41) and variability (p = 0.23). Suboptimal LCE (&lt; 40 HU) was found in 64/133 (48%) patients in the LBW group and 69/141 (49%) in the TBW group, but no examination needed repeating. Conclusions: The calculation of the ICM volume to be administered for abdominal CT based on the LBW does not imply a more consistent LCE

Relevant incidental findings at abdominal multi-detector contrast-enhanced computed tomography : a collateral screening?

AIM: To investigate the prevalence of relevant incidental findings (RIFs) detected during routine abdominal contrast-enhanced computed tomography (CeCT). METHODS: We retrospectively evaluated the reports of a consecutive series of abdominal CeCT studies performed between January and May 2013. For each report, patients' age and sex, admission as inpatient or outpatient, clinical suspicion as indicated by the requesting physician, availability of a previous abdominal examination, and name of the reporting radiologist were recorded. Based on the clinical suspicion, the presence and features of any RIFs (if needing additional workup) was noted. RESULTS: One thousand forty abdominal CeCT were performed in 949 patients (528 males, mean age 66 \ub1 14 years). No significant difference was found between inpatients and outpatients age and sex distribution (P > 0.472). RIFs were found in 195/1040 (18.8%) CeCT [inpatients = 108/470 (23.0%); outpatients = 87/570 (15.2%); P = 0.002]. RIFs were found in 30/440 (6.8%) CeCT with a previous exam and in 165/600 (27.5%) without a previous exam (P < 0.001). Radiologists' distribution between inpatients or outpatients was significantly different (P < 0.001). RIFs prevalence increased with aging, except for a peak in 40-49 year group. Most involved organs were kidneys, gallbladder, and lungs. CONCLUSION: A RIF is detected in 1/5 patients undergoing abdominal CeCT. Risk of overdiagnosis should be taken into account

In vivo detection of choline in ovarian tumors using 3D magnetic resonance spectroscopy

OBJECTIVES: To assess the clinical feasibility of 3-dimensional (3D) proton magnetic resonance spectroscopy (MRS) of ovarian masses at 1.5 T. MATERIALS AND METHODS: We prospectively evaluated 16 patients with 23 ovarian masses using contrast-enhanced magnetic resonance imaging and 3D chemical shift imaging MRS (time of reception/time of echo = 700/135 ms, number of excitations = 6, interpolated voxel = 5 7 5 7 5 mm, water and fat suppression). Spectral editing consisted of water reference, filtering, zero-filling, Fourier transformation, frequency shift, automatic baseline and phase correction, and curve fitting. The volume of interest was placed to encompass both solid and cystic tumor components as well as apparently healthy pelvic tissues. The presence of a choline peak at 3.14 to 3.34 ppm was considered as a marker of malignancy. All patients underwent surgery and histopathological evaluation. RESULTS: Of 23 masses, 19 were malignant and the remaining 4 benign lesions were a fibrothecoma, an endometriosis, a cyst, and a cystadenofibroma. A choline peak was detected in 17/19 malignant tumors (sensitivity 89%), absent in 2 G1 tumors. It was visible in 16 solid components of 19 malignant tumors (in one of them, a choline peak was detected only in the cystic component, in 6 in both solid and cystic components). The choline peak was absent in 20/21 apparently healthy pelvic tissues, with a very low choline peak being detected in one intraperitoneal fluid collection with malignant cells at cytologic analysis; 3/4 benign tumors showed a choline peak (overall specificity 21/25 = 84%). A significant difference between the mean choline peak integral detected within the solid component and that within the cystic component was observed (P = 0.002). No correlation between the choline peak integral and the tumor size was found (r = 0.120, P = 0.615). CONCLUSIONS: 3D MRS of ovarian masses is clinically feasible at 1.5 T. This opens new research strategies for early diagnosis of ovarian cancer