Unenhanced Sequences Research Articles

Measuring synovial thickness on knee MRI in pediatric patients with arthritis: is contrast necessary?

The use of contrast-enhanced imaging has long been standard for magnetic resonance imaging (MRI) assessments of synovitis in juvenile idiopathic arthritis (JIA). However, advancements in MRI technology have allowed for reliable identification of synovium without contrast. To assess the equivalence of unenhanced MRI with contrast-enhanced MRI in evaluating synovial thickness. This is an institutional review board approved, retrospective study performed in a tertiary children's hospital. Pediatric JIA patients under 21 years old were included who underwent knee MRI scans (1.5 T or 3 T) without and with contrast between January 2012 and January 2022. Two radiologists independently measured synovial thickness at 6 knee sites on contrast-enhanced and unenhanced sequences. Numerical measurements and ordinal scores based on juvenile idiopathic arthritis magnetic resonance imaging scoring (JAMRIS) system were recorded, and tests of equivalence were conducted, as well as between-reader and within-reader reliability by concordance correlation coefficient (CCC). All tests were considered significant at the 5% level. A total of 38 studies from 35 patients (25 females, median age 14 years; interquartile range 7 to 15.7) were included. Equivalence was demonstrated at each of the 6 sites for both continuous measurements (P-values < 0.05) and ordinal scores (P-values < 0.05) based on the average over readers. Within-reader reliability was moderate to high (CCC 0.50-0.89), except for the cruciate ligaments site. Averaged over the 6 sites, reliability between readers was low for unenhanced (CCC 0.47, with 95% CI: [0.41, 0.53]) and moderate for contrast-enhanced (CCC 0.64, with 95% CI: [0.59, 0.69]) sequences. Unenhanced knee MRI is equivalent to contrast-enhanced MRI in assessment of synovial thickness using conventional MRI sequences. Contrast material helped improve inter-reader reliability.

Is non-contrast MRI sufficient to detect meningioma residue after surgery?

BackgroundContrast-enhanced magnetic resonance imaging (MRI) is the imaging modality routinely used to follow up patients who have undergone surgical resection of brain meningiomas. There are growing concerns about the massive use of gadolinium-based contrast agents (GBCA). Our aim was to evaluate the performance of a new imaging protocol, performed without GBCA injection, in the detection of tumoral residue or local recurrence after surgery of parafalcine and convexity meningiomas. Materials and methodsOnly adult patients with a documented resected parafalcine or convexity meningioma were included. We performed a dedicated MRI protocol that included non-contrast and post-contrast sequences. The presence or absence of residue on the unenhanced sequences was independently recorded by three observers: first blindly, then in comparison with a baseline enhanced MRI examination. ResultsA total of 51 patients were included. 37 of them featured a tumor residue on the reference enhanced sequence. Overall, an average of 32 of 37 (87%) residues were identified on the unenhanced sequences that were blindly reviewed; and more than 34 of 37 (93%) were identified with the help of the comparative baseline enhanced examination, with a high sensitivity. The missed cases were related to small residues. ConclusionUnenhanced MRI sequences are highly sensitive and specific in identifying a tumor residue or a local recurrence in the post operative follow up of brain meningiomas. Sensitivity is even higher with the help of a comparative baseline enhanced MRI examination, whatever the strength of magnetic field.

The effectiveness of an ultrafast breast MRI protocol in the differentiation of benign and malignant breast lesions

To evaluate the effectiveness of an ultrafast breast magnetic resonance imaging (MRI) protocol in differentiating benign and malignant breast lesions. Fifty-four patients with Breast Imaging Reporting and Data System (BI-RADS) 4 or 5 lesions were recruited between July 2020 to May 2021. A standard breast MRI was performed with the inclusion of the ultrafast protocol between the unenhanced sequence and the first contrast-enhanced sequence. Three radiologists performed image interpretation in consensus. Ultrafast kinetic parameters analysed included the maximum slope (MS), time to enhancement (TTE), and arteriovenous index (AVI). These parameters were compared using receiver operating characteristics with p-values of <0.05 considered to indicate statistical significance. Eighty-three histopathological proven lesions from 54 patients (mean age 53.87 years, SD 12.34, range 26-78 years) were analysed. Forty-one per cent (n=34) were benign and 59% (n=49) were malignant. All malignant and 38.2% (n=13) benign lesions were visualised on the ultrafast protocol. Of the malignant lesions, 77.6% (n=53) were invasive ductal carcinoma (IDC) and 18.4% (n=9) were ductal carcinoma in situ (DCIS). The MS for malignant lesions (13.27%/s) were significantly larger than for benign (5.45%/s; p<0.0001). No significant differences were seen for TTE and AVI. The area under the ROC curve (AUC) for the MS, TTE, and AVI were 0.836, 0.647, and 0.684, respectively. Different types of invasive carcinoma had similar MS and TTE. The MS of high-grade DCIS was also similar to that of IDC. Lower MS values were observed for low-grade (5.3%/s) compared to high-grade DCIS (14.8%/s) but the results were not significant statistically. The ultrafast protocol showed potential to discriminate between malignant and benign breast lesions with high accuracy using MS.

Development and external validation of a multiparametric MRI-based radiomics model for preoperative prediction of microsatellite instability status in rectal cancer: a retrospective multicenter study.

To establish and validate a radiomics model based on multiparametric magnetic resonance imaging (MRI), and to predict microsatellite instability (MSI) status in rectal cancer patients. A total of 199 patients with pathologically confirmed rectal cancer were included. The MSI status was confirmed by immunohistochemistry (IHC) staining. Clinical factors and laboratory data associated with MSI status were analyzed. The imaging data of 100 patients from one of the hospitals were used as the training set. The remaining 99 patients from the other two hospitals were used as the external validation set. The regions of interest (ROIs) were delineated from T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and contrast-enhanced T1WI (CE-T1WI) sequence to extract the radiomics features. The Tree-based approach was used for feature selection. The models were constructed based on the four single sequences and a combination of the four sequences using the random forest (RF) algorithm. The external validation set was used to verify the generalization ability of each model. The receiver operating characteristic (ROC) curves and the area under the curve (AUC) were plotted to evaluate and compare the predictive performance of each model. In the four single-series models, the CE-T1WI model performed the best. The AUCs of the T1WI, T2WI, DWI, and CE-T1WI prediction models in the training set were 0.74, 0.71, 0.71, and 0.78, respectively, while in the external validation set, the corresponding AUCs were 0.67, 0.66, 0.70, and 0.77. The prediction and generalization performance of the combined model of multi-sequences was comparable to that of the CE-T1WI model and it was better than that of the remaining three single-series models, with AUC values of 0.78 and 0.78 in the training and validation sets, respectively. The established radiomics models based on CE-T1WI or multiparametric MRI have similar predictive performance. They have the potential to predict MSI status in rectal cancer patients. • A radiomics model for the prediction of MSI status in patients with rectal cancer was established and validated using external validation. • The models based on CE-T1WI or multiparametric MRI have better predictive performance than those based on single unenhanced sequence images. • The radiomics model has the potential to suggest MSI status in rectal cancer patients; however, it is not yet a substitute for histological confirmation.

Benefits of diffusion-weighted imaging in pediatric acute osteoarticular infections

BackgroundContrast-enhanced magnetic resonance imaging (MRI) is recommended for the diagnosis of acute osteoarticular infections in children. Diffusion-weighted imaging (DWI) may be an alternative to the injection of gadolinium.ObjectiveTo evaluate unenhanced MRI with DWI in comparison to contrast-enhanced MRI for the diagnostic work-up of acute osteoarticular infections in children.Materials and methodsThis retrospective study included 36 children (age range: 7 months-12 years) with extra-spinal osteoarticular infections and MRI performed within 24 h of admission. MRI protocol included short tau inversion recovery (STIR), water-only T2 Dixon, T1, DWI, and gadolinium-enhanced T1 sequences. Two readers reviewed three sets of images: 1) unenhanced sequences, 2) unenhanced sequences with DWI and 3) unenhanced followed by contrast-enhanced sequences (reference standard). Sensitivity and specificity of sets 1 and 2 were compared to set 3 and assessed to identify osteoarticular infections: osteomyelitis (long bones, metaphyseal equivalents), septic arthritis and abscess (soft tissues, bone).ResultsAll 14 cases of osteomyelitis in the metaphyses and diaphyses of long bones and all 27 cases of septic arthritis were identified by unenhanced sequences, but 4/16 abscesses were missed. For the diagnosis of abscess, DWI increased sensitivity to 100%. Among the 18 osteomyelitis in metaphyseal equivalents, 4 femoral head chondroepiphyses were identified by contrast-enhanced sequences only.ConclusionMRI for suspected pediatric acute osteoarticular infections is the best diagnostic modality to guide patient management. An unenhanced protocol with DWI may be an alternative to a contrast-based protocol, even in the presence of an abscess. However, gadolinium remains necessary to assess for chondroepiphyseal involvement of the femoral head.

Avoiding contrast-enhanced sequences does not compromise the precision of the simplified MaRIA for the assessment of non-penetrating Crohn's disease activity.

Patients with Crohn's disease (CD) require multiple assessments with magnetic resonance enterography (MRE) from a young age. Standard MRE protocols for CD include contrast-enhanced sequences. Gadolinium deposits in brain tissue suggest avoiding gadolinium could benefit patients with CD. This study aimed to compare the accuracy of the simplified Magnetic Resonance Index of Activity (sMaRIA) calculated with and without contrast-enhanced sequences in determining the response to biologic drugs in patients with CD. This post hoc analysis of a prospective study included patients with CD with endoscopic ulceration in ≥ 1 intestinal segment starting biologic drug therapy. Two blinded radiologists used the sMaRIA to score images obtained at baseline and week 46 of treatment first using only unenhanced sequences (T2-sMaRIA) and 1month later using both unenhanced and enhanced images (CE-sMaRIA). We calculated the rates of agreement between T2-sMaRIA, CE-sMaRIA, and ileocolonoscopy for different conceptualizations of therapeutic response. A total of 46 patients (median age, 36years [IQR: 28-47]) were included. Agreement with ileocolonoscopy was similar for CE-sMaRIA and T2-sMaRIA in identifying ulcer healing (kappa = 0.74 [0.55-0.93] and 0.70 [0.5-0.9], respectively), treatment response (kappa = 0.53 [0.28-0.79] and 0.44 [0.17 - 0.71]), and remission (kappa = 0.48 [0.22-0.73] and 0.43 [0.17-0.69]). The standardized effect size was moderate for both CE-sMaRIA = 0.63 [0.41-0.85] p < 0.001 and T2-sMaRIA = 0.58 [0.36-0.80] p < 0.001. sMaRIA with and without contrast-enhanced images accurately classified the response according to different therapeutic endpoints determined by ileocolonoscopy. • The simplified Magnetic Resonance Index of Activity is accurate for the assessment of Crohn's disease activity, severity, and therapeutic response, using four dichotomic components that can be evaluated without the need of using contrast-enhanced sequences, representing a practical and safety advantage, but concerns have been expressed as to whether the lack of contrast sequences may compromise precision. • The simplified Magnetic Resonance Index of Activity can assess the response to biologic therapy in patients with Crohn's disease without the need for intravenous contrast agents obtaining comparable results without and with contrast-enhanced sequences. • Avoiding intravenous contrast agents could reduce the duration of the MRE examination and its cost and would increase the acceptance and safety of MRE in clinical research in patients with Crohn's disease.

Automatic discrimination of different sequences and phases of liver MRI using a dense feature fusion neural network: a preliminary study.

To develop and validate a dense feature fusion neural network (DFuNN) to automatically recognize different sequences and phases of liver magnetic resonance imaging (MRI). In total, 3869 sequences and phases from 384 liver MRI examinations, divided into training/validation (n = 2886 sequences from 287 patients) and test (n = 983 sequences from 97 patients) sets, were used in this retrospective study. Ten unenhanced sequences and enhanced phases were included. Manual sequence recognition, performed by two radiologists (20 and 10years of experience) in a consensus reading, was used as the reference standard. The sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC) were calculated to evaluate the performance of the DFuNN on an identical unseen test set. Finally, we evaluated the factors impacting the model precision. A fusion block improved the performance of the DFuNN. DFuNN with a fusion block achieved good recognition performance for both complete and incomplete sequences and phases in the test set. The average sensitivity of recognition performance for complete sequence and phase inputs ranged from 88.06 to 100%, the average specificity ranged from 99.12 to 99.94%, and the median accuracy ranged from 98.02 to 99.95%. The DFuNN prediction accuracy for patients without cirrhosis were significantly higher than those for patients with cirrhosis (P = 0.0153). No significant difference was found in the accuracy across other factors. DFuNN can automatically and accurately identify specific unenhanced MRI sequences and enhanced MRI phases.

Comparison of unenhanced and contrast-enhanced 3T magnetic resonance portovenography in children with extra hepatic portal venous obstruction.

To evaluate role of 3-T magnetic resonance portovenography (MRPV) in children with extra hepatic portal venous obstruction (EHPVO) and compare unenhanced and contrast-enhanced sequences. 20 Children with EHPVO underwent MRPV using unenhanced [T2, T1 pre-contrast, Balanced turbo field echo (BTFE)] and contrast-enhanced (CE) modified DIXON (mDIXON) sequences. The images were evaluated for the patency of abdominal veins, hepatic and splenic parenchyma by two radiologists for interobserver agreement. BTFE and post-contrast mDIXON sequences performed best for evaluation of abdominal veins. Concordance between the BTFE and CE sequences was good to very good for both the radiologists for splenic vein (SV) evaluation. The concordance between the two sequences for evaluation of superior mesenteric vein and its confluence with the SV was less remarkable and varied from fair to good, while the interobserver agreement was very good to perfect. The interobserver agreement between the BTFE and CE sequence for the evaluation of left renal vein was very good, while that for IVC was perfect. The agreement between BTFE and CE sequence was perfect for the evaluation of right and middle hepatic veins, while the interobserver agreement was good to perfect. The interobserver agreement was poor for evaluation of hepatic parenchyma on BTFE sequence as compared to CE sequence, and moderate for splenic parenchyma. BTFE sequence is the single best unenhanced MR pulse sequence to detect all the vascular structures in children with EHPVO. CE-MRI is not superior to BTFE sequence and should be used at the discretion of the radiologist.

Best MRI sequences for identifying axillary lymph node markers in patients with metastatic breast cancer: an inter-reader observational study

BackgroundWe assessed confidence in visualization of markers within metastatic axillary lymph nodes (LNs) on magnetic resonance imaging (MRI), which were placed post-ultrasound (US)-guided biopsy.MethodsA retrospective review was performed on 55 MRI cases between May 2015 and October 2017. Twenty-two MRIs were performed before neoadjuvant therapy, and 33 MRIs were after its initiation. There were 34/55 HydroMARK®, 10/55 Tumark®, and 11/55 other marker types. Time interval between marker placement and MRI examination was 103 ± 81 days (mean ± standard deviation). Three readers with 1–30 years of experience independently assessed four axial sequences: unenhanced fat-suppressed three-dimensional T1-weighted spoiled gradient-recalled (SPGR), first contrast-enhanced fat-suppressed SPGR, T2-weighted water-only fast spin-echo (T2-WO), and T2-weighted fat-only fast-spin-echo (T2-FO).ResultsMarkers were 5.2× more likely to be visualized on T2-WO than on unenhanced images (p = < 0.001), and 3.3× more likely to be visualized on contrast-enhanced than on unenhanced sequences (p = 0.009). HydroMARK markers demonstrated a 3× more likelihood of being visualized than Tumark (p = 0.003). Markers were 8.4× more likely to be visualized within morphologically abnormal LNs (p < 0.001). After 250 days post-placement, confidence in marker brightness of HydroMARK markers on T2-WO images was less than 50% (p < 0.001). Inter-rater agreement was excellent for T2-WO and contrast-enhanced SPGR, good for unenhanced SPGR, and poor for T2-FO images.ConclusionT2-WO and contrast-enhanced images should be used for marker identification. HydroMARK was the best visualized marker. Markers were easier to identify when placed in abnormal LNs. The visibility of HydroMARK markers was reduced with time.

A machine learning approach for differentiating malignant from benign enhancing foci on breast MRI

BackgroundDifferentiate malignant from benign enhancing foci on breast magnetic resonance imaging (MRI) through radiomic signature.MethodsForty-five enhancing foci in 45 patients were included in this retrospective study, with needle biopsy or imaging follow-up serving as a reference standard. There were 12 malignant and 33 benign lesions. Eight benign lesions confirmed by over 5-year negative follow-up and 15 malignant histopathologically confirmed lesions were added to the dataset to provide reference cases to the machine learning analysis. All MRI examinations were performed with a 1.5-T scanner. One three-dimensional T1-weighted unenhanced sequence was acquired, followed by four dynamic sequences after intravenous injection of 0.1 mmol/kg of gadobenate dimeglumine. Enhancing foci were segmented by an expert breast radiologist, over 200 radiomic features were extracted, and an evolutionary machine learning method (“training with input selection and testing”) was applied. For each classifier, sensitivity, specificity and accuracy were calculated as point estimates and 95% confidence intervals (CIs).ResultsA k-nearest neighbour classifier based on 35 selected features was identified as the best performing machine learning approach. Considering both the 45 enhancing foci and the 23 additional cases, this classifier showed a sensitivity of 27/27 (100%, 95% CI 87–100%), a specificity of 37/41 (90%, 95% CI 77–97%), and an accuracy of 64/68 (94%, 95% CI 86–98%).ConclusionThis preliminary study showed the feasibility of a radiomic approach for the characterisation of enhancing foci on breast MRI.

Comparison of End-Expiration Versus End-Inspiration Breath-Holds With Respect to Respiratory Motion Artifacts on T1-Weighted Abdominal MRI.

OBJECTIVE. The purpose of this study was to compare respiratory motion artifact and diagnostic image quality between end-inspiration and end-expiration breath-holding techniques on unenhanced and contrast-enhanced axial T1-weighted MRI of the liver. MATERIALS AND METHODS. This retrospective observational study included 50 consecutive subjects undergoing axial T1-weighted liver MRI, with unenhanced images acquired with both end-inspiration and end-expiration breath-holding techniques, and with contrast-enhanced images acquired for 47 of the subjects with either the end-inspiration or the end-expiration breath-holding technique. Three radiologists performed blinded independent evaluations of each unenhanced sequence, contrast-enhanced sequence, and subtraction (contrast-enhanced minus unenhanced) image, using a scale ranging from 1 point (denoting nondiagnostic imaging) to 5 points (denoting no artifacts). Blinded side-by-side assessment of each pair of unenhanced sequences was also performed. Two-tailed Wilcoxon signed rank and Wilcoxon rank sum tests were used to assess statistical significance. RESULTS. A significant improvement in motion scores was noted for sequences acquired in end-expiration, compared with those acquired in end-inspiration, for unenhanced sequences (mean, 3.35 vs 2.80; p < 0.00001), contrast-enhanced sequences (mean, 4.02 vs 3.46; p = 0.0003), and subtraction images (mean, 3.67 vs 2.41; p < 0.00001). Severe degradation of image quality or nondiagnostic image quality was noted for 15% of unenhanced images (23/150), 0% of contrast-enhanced images, and 8% (5/63) of subtraction images acquired on end-expiration, whereas it was noted for 36% (54/150) of unenhanced images, 13% (10/78) of contrast-enhanced images, and 59% (46/78) of subtraction images acquired on end-inspiration. When side-by-side assessment of paired unenhanced sequences was performed, images acquired in end-expiration were significantly favored in 59% of paired sequences (88/150) (p < 0.00001), and no difference between images acquired with both breath-hold techniques was noted for 21% (32/150) of paired sequences. CONCLUSION. The end-expiration breath-holding technique leads to significant decreases in respiratory motion artifacts, compared with the end-inspiration technique, on unenhanced and contrast-enhanced T1-weighted liver MRI.

Do we need gadolinium-based contrast medium for brain magnetic resonance imaging in children?

Brain imaging is the most common examination in pediatric magnetic resonance imaging (MRI), often combined with the use of a gadolinium-based contrast medium. The application of gadolinium-based contrast medium poses some risk. There is limited evidence of the benefits of contrast medium in pediatric brain imaging. To assess the diagnostic gain of contrast-enhanced sequences in brain MRI when the unenhanced sequences are normal. We retrospectively assessed 6,683 brain MR examinations using contrast medium in children younger than 16years in the pediatric radiology department of the University Hospital Leipzig to determine whether contrast-enhanced sequences delivered additional, clinically relevant information to pre-contrast sequences. All examinations were executed using a 1.5-T or a 3-T system. In 8 of 3,003 (95% confidence interval 0.12-0.52%) unenhanced normal brain examinations, a relevant additional finding was detected when contrast medium was administered. Contrast enhancement led to a change in diagnosis in only one of these cases. Children with a normal pre-contrast brain MRI rarely benefit from contrast medium application. Comparing these results to the risks and disadvantages of a routine gadolinium application, there is substantiated numerical evidence for avoiding routine administration of gadolinium in a pre-contrast normal MRI examination.

The role of MRI in evaluation of recto-sigmoid junction wall endometriosis. A case report

Endometriosis is a condition that occurs due to the presence of endometrial glandular tissue outside the uterine cavity, more frequently at pelvic level affecting ovaries, uterosacral ligament, recto-vaginal septum, sigma or urinary bladder. The diagnosis of endometriosis involves a detailed anamnesis, gynecological examination, imagistic examinations, biochemical investigations, laparoscopy, and histological confirmation. We present herein the case of a 30-year-old patient with severe dysmenorrhea and infertility, diagnosed with profound endometriosis. The patient undergone a magnetic resonance imaging (MRI) pelvic examination with a specific protocol which includes endovaginal and endorectal instillation of gel and involves a scan of the pelvis in three planes (axial, coronal and sagittal) T2-weighted; T2 sequences with inclinations at the level of the uterus, urinary bladder and uterosacral ligaments; T1, T1 Fat Sat sequence unenhanced and post-contrast and T2 sequences post vaginal and rectal instillation of sterile gel. The MRI examination with endovaginal and endorectal instillation of sterile gel has a high specificity and sensitivity in establishing the diagnosis, allowing an accurate evaluation of the various modifications caused by endometriosis and its extent in the wall of pelvic organs. Such an investigation allows an exact preoperative mapping of lesions.

Multiparametric MRI in differentiating pulmonary artery sarcoma and pulmonary thromboembolism: a preliminary experience.

We aimed to define multiparametric magnetic resonance imaging (MRI) findings to differentiate between pulmonary artery sarcoma (PAS) and pulmonary thromboembolism (PTE). Eleven patients with suspected PTE were prospectively included to undergo pulmonary MRI before surgery or biopsy. MRI protocol included an unenhanced sequence, diffusion-weighted imaging (DWI, b=800 s/mm2) and a dynamic contrast-enhanced sequence. Morphologic characteristics including distribution, filling defect, and intensity were observed on T1-, T2-, and fat-suppressed T2-weighted imaging, DWI, and contrast-enhanced MRI. Apparent diffusion coefficient (ADC) values were calculated. Six patients were pathologically diagnosed as PAS and the other five as chronic PTE. There were no significant differences in age, gender, presenting symptoms, D-dimer, and N-terminal pro-brain natriuretic peptide between the two groups (P > 0.05). Among MRI findings that were tested for their ability to diagnose PAS, area under the curve (AUC) was significantly higher than 0.5 for main pulmonary artery involvement (AUC, 0.83±0.13; P = 0.011), hyperintensity on fat-suppressed T2-weighted imaging (AUC, 0.82±0.14; P = 0.025), hyperintensity on DWI (AUC, 0.88±0.12; P = 0.002), contrast enhancement (AUC, 0.92±0.10; P < 0.001) and pleural effusion (AUC, 0.82±0.14; P = 0.025). Moreover, grape-like appearance in distal pulmonary artery and cardiac invasion had 100% specificity for diagnosis of PAS. However, ADC value of PAS was not significantly different than that of chronic PTE (U, 12.00; P = 0.584). Hyperintense filling defect in main pulmonary artery on fat-suppressed T2-weighted imaging and DWI and contrast enhancement may help to discriminate PAS from PTE.

Independent value of image fusion in unenhanced breast MRI using diffusion-weighted and morphological T2-weighted images for lesion characterization in patients with recently detected BI-RADS 4/5 x-ray mammography findings.

The aim of this study was to evaluate the accuracy and applicability of solitarily reading fused image series of T2-weighted and high-b-value diffusion-weighted sequences for lesion characterization as compared to sequential or combined image analysis of these unenhanced sequences and to contrast- enhanced breast MRI. This IRB-approved study included 50 female participants with suspicious breast lesions detected in screening X-ray mammograms, all of which provided written informed consent. Prior to biopsy, all women underwent MRI including diffusion-weighted imaging (DWIBS, b = 1500s/mm2). Images were analyzed as follows: prospective image fusion of DWIBS and T2-weighted images (FU), side-by-side analysis of DWIBS and T2-weighted series (CO), combination of the first two methods (CO+FU), and full contrast-enhanced diagnostic protocol (FDP). Diagnostic indices, confidence, and image quality of the protocols were compared by two blinded readers. Reading the CO+FU (accuracy 0.92; NPV 96.1%; PPV 87.6%) and the CO series (0.90; 96.1%; 83.7%) provided a diagnostic performance similar to the FDP (0.95; 96.1%; 91.3%; p > 0.05). FU reading alone significantly reduced the diagnostic accuracy (0.82; 93.3%; 73.4%; p = 0.023). MR evaluation of suspicious BI-RADS 4 and 5 lesions detected on mammography by using a non-contrast-enhanced T2-weighted and DWIBS sequence protocol is most accurate if MR images were read using the CO+FU protocol. • Unenhanced breast MRI with additional DWIBS/T2w-image fusion allows reliable lesion characterization. • Abbreviated reading of fused DWIBS/T2w-images alone decreases diagnostic confidence and accuracy. • Reading fused DWIBS/T2w-images as the sole diagnostic method should be avoided.

Diagnostic Performance of MRI Sequences for Evaluation of Dural Venous Sinus Thrombosis.

The purpose of this study is to assess the performance of routinely used MRI sequences with and without contrast enhancement in the diagnostic evaluation of dural venous sinus thrombosis (DVST). We identified consecutive patients older than 18 years who underwent concurrent standardized brain MRI and contrast-enhanced (CE) MR venography (MRV) examinations for suspected DVST. The seven MRI sequences that were used (axial unenhanced T1-weighted, T1-weighted CE, T2-weighted, DWI, T2-weighted FLAIR, T2-weighted gradient-recalled echo [GRE], and sagittal 3D T1-weighted GRE CE sequences) were randomized, anonymized, and reviewed independently by two neuroradiologists who were blinded to the final diagnosis. Ten separate venous sinus segments were evaluated. CE MRV was the reference standard for determining the presence or absence of DVST, and it was performed using the following imaging parameters: TR/TE, 4.1-77/1.4-9.5; flip angle, 12-35°; and slice thickness, 0.8-1.4 mm. The diagnostic performance of and interobserver variability for each sequence was assessed per patient and per segment. Thirty-six patients with DVST (72% of whom had acute thrombosis and 28% of whom had chronic thrombosis) and 29 patients without DVST were included in the study. For each sequence, the AUC values for the detection of DVST per patient, as determined by reviewer 1 and reviewer 2, respectively, were as follows: for T1-weighted unenhanced sequences, 55% and 61%; for T1-weighted CE sequences, 79% and 80%; for T2-weighted sequences, 77% and 76%; for DWI sequences, 59% and 64%; for T2-weighted FLAIR sequences, 70% and 72%; for T2-weighted GRE sequences, 64% and 66%; and for the 3D T1-weighted GRE CE sequence, 77% and 81%. The diagnostic performance of the 3D T1-weighted GRE CE sequences was statistically significantly greater than that of the other sequences. Interobserver variability ranged from 0.26 (for T1-weighted unenhanced sequences) to 0.73 (for the DWI sequence). Overall, for each reviewer and with the use of all evaluated sequences, MRI had a high sensitivity (> 99% for both reviewers) but low specificity (14% for reviewer 1 and 48% for reviewer 2) for the detection of DVST. Sequences used in routine brain MRI performed with and without contrast enhancement have varying strengths that are important to recognize when the likelihood of DVST is assessed, but they do not replace the utility of dedicated CE MRV.

Value of diffusion weighted imaging (DWI) and apparent diffusion coefficient factor (ADC) calculation in differentiation of solid breast lesions

ObjectiveTo study the utility of DWI and ADC in increasing the specificity of MRI in differentiating benign from malignant solid breast lesions. Patients and methods56 female patients were included in our study. All patients referred to MRI unit-Radiology Department – Ain Shams University Hospitals to do bilateral breast MRI using conventional sequences, DWI, ADC calculation and post-contrast dynamic study with time/intensity curve using Philips superconductive magnet at 1.5T with breast surface coil. All the patients were subjected to clinical examination, sonomammography as well as written consent. Also, the histopathological results were recorded. Results56 lesions were detected, 30 were benign lesions while the rest 26 were malignant lesions. The sensitivity of the DWI was 100% while the specificity was 80%. The ADC values for the benign lesions were 1.1–2.2×10−3mm2/sec, while the malignant lesions showed ADC values of 0.46–0.99×10−3mm2/sec. The ADC value of 1.1×10−3mm2/sec can be used as the cutoff value in differentiating the benign from the malignant lesions. ConclusionDWI and ADC calculation are short unenhanced sequence that can be inserted easily into MRI protocols to accurately differentiate between the benign and malignant breast lesions.

Safety and efficacy of gadoteric acid in pediatric magnetic resonance imaging: overview of clinical trials and post-marketing studies.

Gadoteric acid is a paramagnetic gadolinium macrocyclic contrast agent approved for use in MRI of cerebral and spinal lesions and for body imaging. To investigate the safety and efficacy of gadoteric acid in children by extensively reviewing clinical and post-marketing observational studies. Data were collected from 3,810 children (ages 3 days to 17 years) investigated in seven clinical trials of central nervous system (CNS) imaging (n = 141) and six post-marketing observational studies of CNS, musculoskeletal and whole-body MR imaging (n = 3,669). Of these, 3,569 children were 2-17 years of age and 241 were younger than 2 years. Gadoteric acid was generally administered at a dose of 0.1 mmol/kg. We evaluated image quality, lesion detection and border delineation, and the safety of gadoteric acid. We also reviewed post-marketing pharmacovigilance experience. Consistent with findings in adults, gadoteric acid was effective in children for improving image quality compared with T1-W unenhanced sequences, providing diagnostic improvement, and often influencing the therapeutic approach, resulting in treatment modifications. In studies assessing neurological tumors, gadoteric acid improved border delineation, internal morphology and contrast enhancement compared to unenhanced MR imaging. Gadoteric acid has a well-established safety profile. Among all studies, a total of 10 children experienced 20 adverse events, 7 of which were thought to be related to gadoteric acid. No serious adverse events were reported in any study. Post-marketing pharmacovigilance experience did not find any specific safety concern. Gadoteric acid was associated with improved lesion detection and delineation and is an effective and well-tolerated contrast agent for use in children.

Contrast-enhanced MR enterography as a stand-alone tool to evaluate Crohn's disease in a paediatric population

To assess the performance of contrast-enhanced T1-weighted magnetic resonance imaging (MRI) alone in the evaluation of Crohn's disease in comparison to all magnetic resonance enterography (MRE) imaging sequences together in an attempt to suggest limitation of the number of overall unenhanced sequences need for the follow-up evaluation. Twenty-five paediatric patients (mean age 14.1 ± 3.7 years, male = 12, female = 13) underwent MRE at 1.5 T for evaluation of Crohn's disease. Two radiologists reviewed only contrast-enhanced T1-weighted images in consensus on the first session. Whole images including unenhanced (steady-state free precession, single-shot fast spin-echo (HASTE), fat-suppressed T2-weighted) and contrast-enhanced T1-weighted sequences were reviewed in consensus during the second session with a 1 month interval, which was used as a reference standard. The readers evaluated the presence or absence of disease in 10 bowel segments in each patient. For the abnormal bowel segments, the readers then evaluated for active versus inactive disease and for the presence or absence of abscess. Sensitivity, specificity, and overall accuracy were calculated for detecting active inflammation. There were 53/250 bowel segments with active inflammation using the reference standard imaging method. The sensitivity, specificity, and accuracy for diagnosing active inflammation using contrast-enhanced images alone were 83.3%, 86.9%, and 84.9%. In five of the false-positive cases of detecting abscess from contrast-enhanced imaging alone, absence of abscesses was confirmed on the non-fat-suppressed HASTE images. The number of MRE sequences in paediatric Crohn's patients can be decreased while maintaining diagnostic accuracy using contrast-enhanced T1 and non-fat-suppressed HASTE images.

Diagnostic accuracy of unenhanced, contrast-enhanced perfusion and angiographic MRI sequences for pulmonary embolism diagnosis: results of independent sequence readings

To independently evaluate unenhanced, contrast-enhanced perfusion and angiographic MR sequences for pulmonary embolism (PE) diagnosis. Prospective investigation, including 274 patients who underwent perfusion, unenhanced 2D steady-state-free-precession (SSFP) and contrast-enhanced 3D angiographic MR sequences on a 1.5-T unit, in addition to CTA (CT angiography). Two independent readers evaluated each sequence independently in random order. Sensitivity, specificity, predictive values and inter-reader agreement were calculated for each sequence, excluding sequences judged inconclusive. Sensitivity was also calculated according to PE location. Contrast-enhanced angiographic sequences showed the highest sensitivity (82.9 and 89.7%, reader 1 and reader 2, respectively), specificity (98.5 and 100%) and agreement (kappa value 0.77). Unenhanced angiographic sequences, although less sensitive overall (68.7 and 76.4%), were sensitive for the detection of proximal PE (92.7 and 100%) and showed high specificity (96.1 and 99.1%) and good agreement (kappa value 0.62). Perfusion sequences showed lower sensitivity (75.0 and 79.3%), specificity (84.8 and 89.7%) and agreement (kappa value 0.51), and a negative predictive value of 84.8% at best. Compared with contrast-enhanced angiographic sequences, unenhanced sequences demonstrate lower sensitivity, except for proximal PE, but high specificity and agreement. The negative predictive value of perfusion sequences was insufficient to safely rule out PE. • Unenhanced angiographic MR sequences are very specific and can identify proximal PE. • Contrast-enhanced MR angiographic sequences show high sensitivity for PE diagnosis. • A normal MR perfusion result does not exclude PE. • Inter-reader agreement is better for angiographic than perfusion MR sequences.