Prediction of infarct size and adverse cardiac outcomes by tissue tracking-cardiac magnetic resonance imaging in ST-segment elevation myocardial infarction.

OBJECTIVES: We investigated whether quantification of global left ventricular (LV) strain by tissue tracking-CMR (TT-CMR) can estimate the infarct size and clinical outcomes in patients with acute myocardial infarction (MI). METHODS: We retrospectively registered 247 consecutive patients (58 ± 12 years; male, 81%) who underwent 1.5-T CMR within 1 month after ST-segment elevation MI (median, 4 days; interquartile range, 3-6 days), and 20 age- and sex-matched controls (58 ± 11 years; male, 80%). TT-CMR analysis was applied to cine-images to measure global LV radial, circumferential and longitudinal peak strains (GRS, GCS and GLS, respectively). Adverse cardiac events were defined as cardiac death and hospitalization for heart failure. RESULTS: During the follow-up (median, 7.8 years), 20 patients (8.1%) experienced adverse events. LV myocardial deformation was significantly decreased in MI patients compared to controls and closely related to the infarct size. The GRS, GCS and GLS were all significant predictors of adverse cardiac events. In particular, a GLS > -14.1% was independently associated with a > 5-fold increased risk for adverse events, even after adjustment for the LV ejection fraction and infarct size. CONCLUSIONS: TT-CMR-derived LV strain is significantly related to the infarct size and adverse events. GLS measurement provides strong prognostic information in MI patients. KEY POINTS: • TT-CMR provides reliable quantification of LV strain in MI patients. • TT-CMR allows prediction of the infarct size and adverse events. • In particular, GLS by TT-CMR had independent prognostic value in MI patients.

Disproportionate fluid sign as an aid in diagnosing high-grade bursal-sided supraspinatus tendon tear.

Background Deep, high-grade bursal-sided supraspinatus tendon tears are sometimes preoperatively misinterpreted as full-thickness tears on shoulder magnetic resonance imaging (MRI). Purpose To determine the usefulness of disproportionate fluid sign for differentiating high-grade bursal-sided partial-thickness tears from full-thickness tears on conventional MRI. Material and Methods Preoperative MRIs of 198 patients with arthroscopically confirmed high-grade bursal-sided partial-thickness tears and full-thickness tears were independently reviewed by two readers on two occasions. The presence of high-grade bursal-sided partial-thickness tears with a confidence level using a five-point grading scale was assessed based on tear depth alone and also in combination with disproportionate fluid sign, defined as a prominent subdeltoid or subacromial-subdeltoid bursal fluid distension with a relative paucity of effusion in the glenohumeral joint. The sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC) were calculated, as well as inter-observer reliability. Results The disproportionate fluid sign was identified in 60/74 (81.2%) bursal-sided partial-thickness tears and 9/124 (7.5%) full-thickness tears. The sensitivity and accuracy of the diagnosis of bursal-sided tear were higher when disproportionate fluid sign was used in conjunction with the tear depth, compared with tear depth alone ( P < 0.001). There was excellent inter-observer agreement for disproportionate fluid sign and deep bursal-sided tear. The AUCs were significantly higher in combination with disproportionate fluid sign. Conclusion The disproportionate fluid sign indicates the presence of a deep, high-grade bursal-sided partial-thickness tear, which can be misinterpreted as a full-thickness tear. Thus, it can provide greater diagnostic assistance to less-experienced radiologists and clinicians.

Image-Based Analysis of Tumor Localization After Intra-Arterial Delivery of Technetium-99m-Labeled SPIO Using SPECT/CT and MRI.

The aim of this study is to evaluate the localization of 99mTc-labeled dextran-coated superparamagnetic iron oxide (SPIO) nanoparticles to the liver tumor using image-based analysis. We delivered 99mTc-SPIO intravenously or intra-arterially (IA) with/without Lipiodol to compare the tumor localization by gamma scintigraphy, single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) in a rabbit liver tumor. The gamma and SPECT image-based analysis shows that the uptake ratio of the tumor to the normal liver parenchyma is highest after delivery of 99mTc-SPIO with Lipiodol IA and that well correlates with the trend of the signal decrease in the liver MRIs. Intra-arterial delivery of SPIO with Lipiodol might be a good drug delivery system targeting the hepatic tumors, as confirmed by image-based analysis.

Usefulness of a metal artifact reduction algorithm for orthopedic implants in abdominal CT: phantom and clinical study results.

OBJECTIVE. The purpose of this study was to evaluate the usefulness of a metal artifact reduction (MAR) algorithm for orthopedic prostheses in phantom and clinical CT. MATERIALS AND METHODS. An agar phantom with two sets of spinal screws was scanned at various tube voltage (80-140 kVp) and tube current-time (34-1032 mAs) settings. The orthopedic MAR algorithm was combined with filtered back projection (FBP) or iterative reconstruction. The mean SDs in three ROIs were compared among four datasets (FBP, iterative reconstruction, FBP with orthopedic MAR, and iterative reconstruction with orthopedic MAR). For the clinical study, the mean SDs of three ROIs and 4-point scaled image quality in 52 patients with metallic orthopedic prostheses were compared between CT images acquired with and without orthopedic MAR. The presence and type of image quality improvement with orthopedic MAR and the presence of orthopedic MAR-related new artifacts were also analyzed. RESULTS. In the phantom study, the mean SD with orthopedic MAR was significantly lower than that without orthopedic MAR regardless of dose settings and reconstruction algorithms (FBP versus iterative reconstruction). The mean SD near the metallic prosthesis in 52 patients was significantly lower on CT images with orthopedic MAR (28.04 HU) than those without it (49.21 HU). Image quality regarding metallic artifact was significantly improved with orthopedic MAR (rating of 2.60 versus 1.04). Notable reduction of metallic artifacts and better depiction of abdominal organs were observed in 45 patients. Diagnostic benefit was achieved in six patients, but orthopedic MAR-related new artifacts were seen in 30 patients. CONCLUSION. Use of the orthopedic MAR algorithm significantly reduces metal artifacts in CT of both phantoms and patients and has potential for improving diagnostic performance in patients with severe metallic artifacts.

Usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer.

PURPOSE: To demonstrate the usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer. MATERIALS AND METHODS: Fifty-four patients with rectosigmoid colon cancers underwent routine CT without (n=27) and with (n=27) rectum distension using a sonographic gel. Rectum distensibility and tumor visualization were evaluated. T and N stages on CT independently recorded by two radiologists were correlated with pathologic staging. Staging accuracies were compared using Fisher's exact test. Diagnostic performances in differentiating