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The development of protein-based hydrogels for tissue engineering applications is often limited by their mechanical properties. Herein, we present the facile fabrication of tough regenerated silk fibroin (RSF)/graphene oxide (GO) nanocomposite hydrogels by a photochemical cross-linking method. The RSF/GO composite hydrogels demonstrated soft and adhesive properties during initial stages of photocrosslinking (<2 min), which is not observed for the pristine RSF hydrogel, and rendered a tough and nonadhesive hydrogel upon complete cross-linking (10 min). The composite hydrogels exhibited superior tensile mechanical properties, increased β-sheet content, and decreased chain mobility compared to that of the pristine RSF hydrogels. The composite hydrogels demonstrated Young's modulus as high as ∼8 MPa, which is significantly higher than native cartilage (∼1.5 MPa), and tensile toughness as high as ∼2.4 MJ/m 3 , which is greater than that of electroactive polymer muscles and at par with RSF/GO composite membranes fabricated by layer-by-layer assembly. Small-angle scattering study reveals the hierarchical structure of photocrosslinked RSF hydrogels to comprise randomly distributed water-poor (hydrophobic) and water-rich (hydrophilic) regions at the nanoscale, whereas water pores and channels exhibiting fractal-like characteristics at the microscale. The size of hydrophobic domain (containing β-sheets) was observed to increase slightly with GO incorporation and/or alcohol post-treatment, whereas the size of the hydrophilic domain (intersheet distance containing random coils) was observed to increase significantly, which influences/affects water uptake capacity, cross-link density, and mechanical properties of hydrogels. The presented results have implications for both fundamental understanding of the structure-property relationship of RSF-based hydrogels and their technological applications.

Background and Purpose: Intrinsic T1-hyperintense signal has recently been reported in the deep gray nuclei on brain MR imaging after multiple doses of gadolinium-based contrast agents. Most reports have included adult patients and excluded those undergoing radiation or chemotherapy. We investigated whether T1 shortening is also observed in children and tried to determine whether radiochemotherapy is a risk factor for this phenomenon., Materials and Methods: In this single-center retrospective study, we reviewed clinical charts and images of all patients 18 years of age or younger with ≥4 gadobenate dimeglumine-enhanced MRIs for 6 years. Seventy-six children (mean age, 9.3 years; 60 unconfounded by treatment, 16 with radiochemotherapy) met the selection criteria (>4 MR imaging examinations; mean, 8). T1 signal intensity ratios for the dentate to pons and globus pallidus to thalamus were calculated and correlated with number of injections, time interval, and therapy., Results: Among the 60 children without radiochemotherapy, only 2 had elevated T1 signal intensity ratios ( n = 20 and 16 injections). Twelve of the 16 children with radiochemotherapy showed elevated signal intensity ratios. Statistical analysis demonstrated a significant signal intensity ratio change for the number of injections ( P < .001) and amount of gadolinium ( P = .008), but not for the interscan time interval ( P = .35). There was a significant difference in the average signal intensity ratio change between those with and without radiochemotherapy ( P < .001). Chart review revealed no new neurologic deficits in any patients, related to their underlying conditions and prior surgeries., Conclusions: Compared with published adult series, children show a similar pattern of T1 hyperintense signal changes of the dentate and globus pallidus after multiple gadobenate dimeglumine injections. The T1 signal changes in children may have a later onset but are accelerated by radiochemotherapy., (© 2018 by American Journal of Neuroradiology.)

Determining whether an asymptomatic individual with Prostate-Specific Antigen (PSA) levels below 20 ng ml -1 has prostate cancer in the absence of definitive, biopsy-based evidence continues to present a significant challenge to clinicians who must decide whether such individuals with low PSA values have prostate cancer. Herein, we present an advanced computational data extraction approach which can identify the presence of prostate cancer in men with PSA levels <20 ng ml -1 on the basis of peripheral blood immune cell profiles that have been generated using multi-parameter flow cytometry. Statistical analysis of immune phenotyping datasets relating to the presence and prevalence of key leukocyte populations in the peripheral blood, as generated from individuals undergoing routine tests for prostate cancer (including tissue biopsy) using multi-parametric flow cytometric analysis, was unable to identify significant relationships between leukocyte population profiles and the presence of benign disease (no prostate cancer) or prostate cancer. By contrast, a Genetic Algorithm computational approach identified a subset of five flow cytometry features ( CD 8 + CD 45 RA - CD 27 - CD 28 - ( CD 8 + Effector Memory cells); CD 4 + CD 45 RA - CD 27 - CD 28 - ( CD 4 + Terminally Differentiated Effector Memory Cells re-expressing CD45RA); CD 3 - CD 19 + (B cells); CD 3 + CD 56 + CD 8 + CD 4 + (NKT cells)) from a set of twenty features, which could potentially discriminate between benign disease and prostate cancer. These features were used to construct a prostate cancer prediction model using the k-Nearest-Neighbor classification algorithm. The proposed model, which takes as input the set of flow cytometry features, outperformed the predictive model which takes PSA values as input. Specifically, the flow cytometry-based model achieved Accuracy = 83.33%, AUC = 83.40%, and optimal ROC points of FPR = 16.13%, TPR = 82.93%, whereas the PSA-based model achieved Accuracy = 77.78%, AUC = 76.95%, and optimal ROC points of FPR = 29.03%, TPR = 82.93%. Combining PSA and flow cytometry predictors achieved Accuracy = 79.17%, AUC = 78.17% and optimal ROC points of FPR = 29.03%, TPR = 85.37%. The results demonstrate the value of computational intelligence-based approaches for interrogating immunophenotyping datasets and that combining peripheral blood phenotypic profiling with PSA levels improves diagnostic accuracy compared to using PSA test alone. These studies also demonstrate that the presence of cancer is reflected in changes in the peripheral blood immune phenotype profile which can be identified using computational analysis and interpretation of complex flow cytometry datasets.

Structural variations of the thoracic outlet create a unique risk for neurogenic thoracic outlet syndrome (nTOS) that is difficult to diagnose clinically. Common anatomical variations in brachial plexus (BP) branching were recently discovered in which portions of the proximal plexus pierce the anterior scalene. This results in possible impingement of BP nerves within the muscle belly and, therefore, predisposition for nTOS. We hypothesized that some cases of disputed nTOS result from these BP branching variants. We tested the association between BP piercing and nTOS symptoms, and evaluated the capability of ultrasonographic identification of patients with clinically relevant variations. Eighty-two cadaveric necks were first dissected to assess BP variation frequency. In 62.1%, C5, superior trunk, or superior + middle trunks pierced the anterior scalene. Subsequently, 22 student subjects underwent screening with detailed questionnaires, provocative tests, and BP ultrasonography. Twenty-one percent demonstrated atypical BP branching anatomy on ultrasound; of these, 50% reported symptoms consistent with nTOS, significantly higher than subjects with classic BP anatomy (14%). This group, categorized as a typical TOS, would be missed by provocative testing alone. The addition of ultrasonography to nTOS diagnosis, especially for patients with BP branching variation, would allow clinicians to visualize and identify atypical patient anatomy., Competing Interests: The authors declare no conflict of interest.

Tumor-propagating cells (TPCs) share self-renewal properties with normal stem cells and drive continued tumor growth. However, mechanisms regulating TPC self-renewal are largely unknown, especially in embryonal rhabdomyosarcoma (ERMS)-a common pediatric cancer of muscle. Here, we used a zebrafish transgenic model of ERMS to identify a role for intracellular NOTCH1 (ICN1) in increasing TPCs by 23-fold. ICN1 expanded TPCs by enabling the de-differentiation of zebrafish ERMS cells into self-renewing myf5+ TPCs, breaking the rigid differentiation hierarchies reported in normal muscle. ICN1 also had conserved roles in regulating human ERMS self-renewal and growth. Mechanistically, ICN1 upregulated expression of SNAIL1, a transcriptional repressor, to increase TPC number in human ERMS and to block muscle differentiation through suppressing MEF2C, a myogenic differentiation transcription factor. Our data implicate the NOTCH1/SNAI1/MEF2C signaling axis as a major determinant of TPC self-renewal and differentiation in ERMS, raising hope of therapeutically targeting this pathway in the future., (Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.)

Cells acquire the invasive and migratory properties necessary for the invasion-metastasis cascade and the establishment of aggressive, metastatic disease by reactivating a latent embryonic programme: epithelial-to-mesenchymal transition (EMT). Herein, we report the development of a new, spontaneous model of EMT which involves four phenotypically distinct clones derived from a primary tumour-derived human prostate cancer cell line (OPCT-1), and its use to explore relationships between EMT and the generation of cancer stem cells (CSCs) in prostate cancer. Expression of epithelial (E-cadherin) and mesenchymal markers (vimentin, fibronectin) revealed that two of the four clones were incapable of spontaneously activating EMT, whereas the others contained large populations of EMT-derived, vimentin-positive cells having spindle-like morphology. One of the two EMT-positive clones exhibited aggressive and stem cell-like characteristics, whereas the other was non-aggressive and showed no stem cell phenotype. One of the two EMT-negative clones exhibited aggressive stem cell-like properties, whereas the other was the least aggressive of all clones. These findings demonstrate the existence of distinct, aggressive CSC-like populations in prostate cancer, but, importantly, that not all cells having a potential for EMT exhibit stem cell-like properties. This unique model can be used to further interrogate the biology of EMT in prostate cancer.

Purpose: In the era of increasingly complex surgical techniques for peripheral nerve repair, there is a need for high spatial resolution imaging of the neural plexuses in the body. We describe our experience with chemical shift encoded MRI and its implications for patient management., Materials and Methods: IDEAL water-fat separation is a chemical shift based method of homogeneously suppressing signal from fat, while maintaining adequate signal. This technique was used in clinical practice and the patient images reviewed., Results: IDEAL water-fat separation was shown to improve visualization of the brachial and lumbosacral plexuses with good fat suppression and high signal to noise ratio., Conclusion: IDEAL water - fat separation is an excellent technique to use in the imaging of the brachial and lumbosacral plexuses as it balances the need for homogeneous fat suppression with maintenance of excellent signal to noise ratio., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Introduction: Opioids are commonly used in the postoperative period to manage postsurgical pain. However, adverse side effects of opioids include respiratory depression, urinary retention, pruritus, vomiting, nausea, constipation, and increased risk of falls. Surgical site infiltration with extended release liposomal bupivacaine is effective in the multimodal care plan of managing postsurgical patients. The purpose of the present study was to examine the possible effects of liposomal bupivacaine on postoperative opioid adverse events following open hernia repair and laparoscopic colon resection surgery., Materials and Methods: The study population comprised 82 patients who had undergone open hernia repair or a laparoscopic colon resection. Forty-five of the 82 patients were treated with liposomal bupivacaine. Data were examined retrospectively from January 1, 2012 to August 31, 2012 in comparison with historical controls. Adverse opioid events measured included constipation, pruritus, vomiting, nausea, urinary retention, respiratory depression and fall risk. Statistical tools used were the Mann-Whitney U test, Pearson's chi-squared test, and Fisher's exact test., Results: The addition of liposomal bupivacaine did significantly (p<0.05) reduce urinary retention and respiratory depression. Additionally, from the perspective of hospital safety there was a significant reduction in patients at high risk of falls, from 16% to 8.4% as well as an increase in patients at low risk of falls, from 37.6% to 48.7%., Conclusion: The findings of this study demonstrate that using liposomal bupivacaine can significantly reduce high-risk fall patients, increase low-risk fall patients as well as decrease urinary retention and respiratory depression in the postoperative setting. Given heightened consideration of the impact of sentinel events on hospital reimbursement since health care reforms in 2014, these results are important because they can mitigate complications associated with opioids in postsurgical pain management, and thereby reduce the costs of hospitalization.

Background: One of the well-established methods used to determine endurance training intensity for patients in outpatient cardiac rehabilitation (CR) is to take a percentage (70%-85%) of the maximal or peak heart rate (HRmax) from a recent postevent symptom-limited graded exercise test (GXT). Because many patients are referred to CR without having had a maximal GXT, a current practice is to use 30% to 50% above resting heart rate (RHR) to estimate endurance training intensity., Objective: The purpose of this study was to determine if a target heart rate (THR) of 30% to 50% above RHR approximated a THR of 70% to 85% of the HRmax achieved on GXT (HRmax GXT) and provided equivalent exercise intensity based on ratings of perceived exertion (RPE) and metabolic equivalency thresholds (METs)., Methods: A retrospective chart review of 53 patients enrolled in CR and had documentation of postevent GXT was conducted to determine the patient's mean exercise heart rate (HR) achieved at each session to percentage above RHR and percentage HRmax GXT. Analysis was conducted to determine and compare patients' HRs, RPE, and MET levels when patients were exercising within the THR ranges of 30% to 50% above RHR and 70% to 85% HRmax GXT., Results: A THR range of 30% to 50% above RHR approximated 60% to 70% HRmax GXT. Mean exercise HRs progressed from 39% to 49% above RHR sessions 2 to 6 with mean (SD) RPE of 10.58 (0.55) to 11.44 (0.68) on the Borg scale and mean (SD) MET level of 2.91 (0.55) to 3.31 (0.6). Mean exercise HRs progressed to 54% to 65% above RHR sessions 7 to 18 and approximated 70% to 73% HRmax GXT. Mean (SD) RPE at this intensity ranged from 11.57 (0.58) to 12.21 (0.53) with a mean (SD) MET level of 3.47 (0.6) to 3.8 (0.77)., Conclusion: In the observed population, a THR of 30% to 50% above RHR underestimated the THR range of 70% to 85% HRmax GXT but provided adequate exercise intensity for patients at the beginning of a CR program based on percentage HRmax GXT, RPE and MET levels.

Purpose: To investigate flip angle (FA)-dependent T1 bias in chemical shift-encoded fat-fraction (FF) and to evaluate a strategy for correcting this bias to achieve accurate MRI-based estimates of liver fat with optimized signal-to-noise ratio (SNR)., Materials and Methods: Thirty-three obese patients, 14 men/19 women, aged 57.3 ± 13.9 years underwent 3 Tesla (T) liver MRI including MR-spectroscopy and four three-echo-complex chemical shift-encoded MRI sequences using different FAs (1°/3°/10°/20°). FF was estimated with R2* correction and multi-peak fat spectral modeling. The FF for each FA with and without T1 correction was compared with spectroscopy as a reference standard, using linear regression. Relative SNR of the magnitude data were assessed for each flip angle., Results: The correlation between chemical shift-encoded MRI and spectroscopy was high (R(2) &asymp; 0.9). Without T1 correction, the agreement of both techniques showed no significant differences in slope (PFlipAngle1 °  = 0.385/PFlipAngle3 °  = 0.289) using low FA. High FA resulted in significant different slopes (PFlipAngle10 °  = 0.016/PFlipAngle20 °  = 0.014. T1 bias was successfully corrected using the T1 correction strategy (slope:PFlipAngle10 °  = 0.387/PFlipAngle20 °  = 0.440). Additionally, the use of high FA (near the Ernst angle) improved the SNR of the magnitude data (FA1 vs. FA3; respectively FA1 vs. FA10 P ≤ 0.001)., Conclusion: T1 bias is a strong confounder in the assessment of liver fat using chemical shift imaging with high FA. However, using a larger flip angle with T1 correction leads to higher SNR, and residual error after T1 correction is very small., (© 2013 Wiley Periodicals, Inc.)

Background and Purpose: The chronic cerebrospinal venous insufficiency hypothesis raises interest in cerebrospinal venous blood flow imaging, which is more complex and less established than in arteries. For accurate assessment of venous flow in chronic cerebrospinal venous insufficiency diagnosis and research, we must account for physiologic changes in flow patterns. This study examines day-to-day flow variability in cerebrospinal veins by use of 4D MR flow and contrast-enhanced MRA under typical, uncontrolled conditions in healthy individuals., Materials and Methods: Ten healthy volunteers were scanned in a test-retest fashion by use of a 4D flow MR imaging technique and contrast-enhanced MRA. Flow parameters obtained from phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA scoring measurements in the head, neck, and chest veins were analyzed for internal consistency and interscan reproducibility., Results: Internal consistency was satisfied at the torcular herophili, with an input-output difference of 2.2%. Percentages of variations in flow were 20.3%, internal jugular vein; 20.4%, azygos vein; 6.8%, transverse sinus; and 5.1%, common carotid artery. Retrograde flow was found in the lower internal jugular vein (4.8%) and azygos vein (7.2%). Contrast-enhanced MRA interscan κ values for the internal jugular vein (left: 0.474, right: 0.366) and azygos vein (-0.053) showed poor interscan agreement., Conclusions: Phase contrast-vastly undersampled isotropic projection reconstruction blood flow measurements are reliable and highly reproducible in intracranial veins and in the common carotid artery but not in veins of the neck (internal jugular vein) and chest (azygos vein) because of normal physiologic variation. Retrograde flow normally may be observed in the lower internal jugular vein and azygos vein. Low interrater agreement in contrast-enhanced MRA scans was observed. These findings have important implications for imaging diagnosis and experimental research of chronic cerebrospinal venous insufficiency., (© 2014 by American Journal of Neuroradiology.)

Study Objective: Obstructive sleep apnea is prevalent among people with asthma, but underlying mechanisms remain unknown. Inhaled corticosteroids may contribute. We tested the effects of orally inhaled fluticasone propionate (FP) on upper airway (UAW) during sleep and wakefulness., Study Design: 16-week single-arm study., Participants: 18 (14 females, mean [ ± SD] age 26 ± 6 years) corticosteroid-naïve subjects with mild asthma (FEV1 89 ± 8% predicted)., Interventions: High dose (1,760 mcg/day) inhaled FP., Measurements: (1) UAW collapsibility (passive critical closing pressure [Pcrit]); (2) tongue strength (maximum isometric pressure-Pmax, in KPa) and endurance-time (in seconds) able to maintain 50% Pmax across 3 trials (Ttot)-at anterior and posterior locations; (3) fat fraction and volume around UAW, measured by magnetic resonance imaging in three subjects., Results: Pcrit overall improved (became more negative) (mean ± SE) (-8.2 ± 1.1 vs. -12.2 ± 2.2 cm H2O, p = 0.04); the response was dependent upon baseline characteristics, with older, male gender, and worse asthma control predicting Pcrit deterioration (less negative). Overall, Pmax increased (anterior p = 0.02; posterior p = 0.002), but Ttot generally subsided (anterior p = 0.0007; posterior p = 0.06), unrelated to Pcrit response. In subjects studied with MRI, fat fraction and volume increased by 20.6% and 15.4%, respectively, without Pcrit changes, while asthma control appeared improved., Conclusions: In this study of young, predominantly female, otherwise healthy subjects with well-controlled asthma and stiff upper airways, 16-week high dose FP treatment elicited Pcrit changes which may be dependent upon baseline characteristics, and determined by synchronous and reciprocally counteracting local and lower airway effects. The long-term implications of these changes on sleep disordered breathing severity remain to be determined.

Purpose: To evaluate the effect of flip angle (FA) on accuracy and within-examination repeatability of hepatic proton-density fat fraction (PDFF) estimation with complex data-based magnetic resonance imaging (MRI)., Materials and Methods: PDFF was estimated at 3T in 30 subjects using two sets of five MRI sequences with FA from 1° to 5° in each set. One set used 7 msec repetition time and acquired 6 echoes (TR7/E6); the other used 14 msec and acquired 12 echoes (TR14/E12). For each FA in both sets the accuracy of MRI-PDFF was assessed relative to MR spectroscopy (MRS)-PDFF using four regression parameters (slope, intercept, average bias, R(2) ). Each subject had four random sequences repeated; within-examination repeatability of MRI-PDFF for each FA was assessed with intraclass correlation coefficient (ICC). Pairwise comparisons were made using bootstrap-based tests., Results: Most FAs provided high MRI-PDFF estimation accuracy (intercept range -1.25 to 0.84, slope 0.89-1.06, average bias 0.24-1.65, R(2) 0.85-0.97). Most comparisons of regression parameters between FAs were not significant. Informally, in the TR7/E6 set, FAs of 2° and 3° provided the highest accuracy, while FAs of 1° and 5° provided the lowest. In the TR14/E12 set, accuracy parameters did not differ consistently between FAs. FAs in both sets provided high within-examination repeatability (ICC range 0.981-0.998)., Conclusion: MRI-PDFF was repeatable and, for most FAs, accurate in both sequence sets. In the TR7/E6 sequence set, FAs of 2° and 3° informally provided the highest accuracy. In the TR14/E12 sequence set, all FAs provided similar accuracy., (Copyright © 2013 Wiley Periodicals, Inc.)

Objective: To investigate multi-echo chemical shift-encoded MRI-based mapping of proton density fat fraction (PDFF) and fat-corrected R2* in bone marrow as biomarkers for osteoporosis assessment., Methods: Fifty-one patients (28 female; mean age 69.7 ± 9.0 years) underwent dual energy X-ray absorptiometry (DXA). On the basis of the t score, 173 valid vertebrae bodies were divided into three groups (healthy, osteopenic and osteoporotic). Three echo chemical shift-encoded MRI sequences were acquired at 3 T. PDFF and R2* with correction for multiple-peak fat (R2*MP) were measured for each vertebral body. Kruskal-Wallis test and post hoc analysis were performed to evaluate differences between groups. Further, the area under the curve (AUC) for each technique was calculated using logistic regression analysis., Results: On the basis of DXA, 92 samples were normal (53 %), 47 osteopenic (27 %) and 34 osteoporotic (20 %). PDFF was increased in osteoporosis compared with healthy (P = 0.007). R2*MP showed significant differences between normal and osteopenia (P = 0.004), and between normal and osteoporosis (P < 0.001). AUC to differentiate between normal and osteoporosis was 0.698 for R2*MP, 0.656 for PDFF and 0.74 for both combined., Conclusion: PDFF and R2*MP are moderate biomarkers for osteoporosis. PDFF and R2*MP combination might improve the prediction in differentiating healthy subjects from those with osteoporosis.

Heart failure (HF) is a costly chronic disease that affects 5.7 million people in the United States. Home healthcare agencies are implementing initiatives to reduce hospitalizations and manage HF patients at home. In this study, telemonitoring improved patients' perception of their quality of life and assisted them to sustain critical self-care behaviors. Patients who were monitored had fewer hospitalizations but telemonitoring was not statistically significant in lowering hospitalizations.

Estrogen deficiency changes the regional distribution of tissue mineral density leading to alteration of the mechanical properties of bone at the tissue level. Direct measurement of the regional variation of elastic modulus and viscosity, which is the capacity to resist time-dependent viscoelastic deformation, will aid in our understanding of how estrogen deficiency alters bone quality. It was observed that, compared to bone from other anatomical sites, the jaw bone is less sensitive to estrogen deficiency. Thus, the objective of this study was to examine the effect of estrogen deficiency on (1) the regional variations of tissue modulus and viscosity of bone using nanoindentation, and (2) the modulus-viscosity relationships in jaw and vertebral bones for comparison between different anatomical sites. Mandibular and vertebral bone specimens of sham surgery and ovariectomized (OVX) rat groups were subject to nanoindentation in hydration. Indentation modulus and viscosity were measured at relatively new (less mineralized) tissue regions and at the corresponding pre-existing old (more mineralized) tissue regions of mandibular and vertebral bones. In the mandibular bones, significant regional variations of indentation modulus and viscosity were observed (p<0.039) and OVX increased the indentation viscosity. While significant positive correlations were found between indentation modulus and viscosity (p<0.001), the correlation slopes for the mandibular and vertebral bones were significant different (p<0.001). The current results indicated that changes in viscoelastic property and its regional variation should be examined to obtain a better understanding of estrogen deficiency-dependent alteration of bone quality., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Time-resolved cardiac imaging is particularly interesting in the interventional setting since it would provide both image guidance for accurate procedural planning and cardiac functional evaluations directly in the operating room. Imaging the heart in vivo using a slowly rotating C-arm system is extremely challenging due to the limitations of the data acquisition system and the high temporal resolution required to avoid motion artifacts. In this paper, a data acquisition scheme and an image reconstruction method are proposed to achieve time-resolved cardiac cone-beam computed tomography imaging with isotropic spatial resolution and high temporal resolution using a slowly rotating C-arm system. The data are acquired within 14 s using a single gantry rotation with a short scan angular range. The enabling image reconstruction method is the prior image constrained compressed sensing (PICCS) algorithm. The prior image is reconstructed from data acquired over all cardiac phases. Each cardiac phase is then reconstructed from the retrospectively gated cardiac data using the PICCS algorithm. To validate the method, several studies were performed. Both numerical simulations using a hybrid motion phantom with static background anatomy as well as physical phantom studies have been used to demonstrate that the proposed method enables accurate reconstruction of image objects with a high isotropic spatial resolution. A canine animal model scanned in vivo was used to further validate the method.

Purpose: To implement IDEAL (iterative decomposition of water and fat using echo asymmetry and least squares estimation) water-fat separation with 3D time-of-flight (TOF) magnetic resonance angiography (MRA) of intracranial vessels for improved background suppression by providing uniform and robust separation of fat signal that appears bright on conventional TOF-MRA., Materials and Methods: IDEAL TOF-MRA and conventional TOF-MRA were performed in volunteers and patients undergoing routine brain MRI/MRA on a 3T magnet. Images were reviewed by two radiologists and graded based on vessel visibility and image quality., Results: IDEAL TOF-MRA demonstrated statistically significant improvement in vessel visibility when compared to conventional TOF-MRA in both volunteer and clinical patients using an image quality grading system. Overall image quality was 3.87 (out of 4) for IDEAL versus 3.55 for conventional TOF imaging (P = 0.02). Visualization of the ophthalmic artery was 3.53 for IDEAL versus 1.97 for conventional TOF imaging (P < 0.00005) and visualization of the superficial temporal artery was 3.92 for IDEAL imaging versus 1.97 for conventional TOF imaging (P < 0.00005)., Conclusion: By providing uniform suppression of fat, IDEAL TOF-MRA provides improved background suppression with improved image quality when compared to conventional TOF-MRA methods.

In time-resolved MRA (TR MRA), injection parameters and contrast agent (CA) dose are important factors influencing image quality. In this study, three different injection schemes with different CA volumes were evaluated in 12 healthy volunteers. Injection rates between 0.2 and 0.8 ml/s were evaluated with CA volumes of 10 and 20 ml. To measure circulatory parameters, cine cardiac MRI was performed before each exam. Spatial resolution could be reduced to 2 x 1.4 x 2 mm3, temporal resolution was 2.25 s/frame. To exclude signal saturation at high CA concentrations, a phantom with fixed CA concentrations was placed in the field of view. SNR was measured, and the area under the curve of the arterial signal of the different injection schemes was calculated. Results showed the largest diagnostic window at a relatively slow injection rate of 0.4 ml/s and a CA volume of 10 ml. Circulatory parameters have an important impact on CA arrival, so delay times have to be set depending on these parameters.

[11C]PHNO is a recently introduced agonist to image DA D2-like receptors with Positron Emission Tomography (PET). In cats and humans, [11C]PHNO revealed an atypical distribution compared to radiolabeled D2-like antagonists (such as [11C]raclopride) or other D2-like agonists (such as [11C]NPA), as it displayed unusual high binding in the globus pallidus (GP). The goal of this study was to assess the pharmacological nature of the binding of [11C]PHNO in the GP in nonhuman primates. As previously reported in humans, [11C]PHNO equilibrium specific to nonspecific equilibrium partition coefficients (V3'') in baboons was much higher in GP (3.88 +/- 1.15) than in the dorsal striatum (DST, 2.07 +/- 0.43), whereas the reverse was true for [11C]raclopride (1.48 +/- 0.41 in GP, 2.56 +/- 0.91 in DST) and [11C]NPA (0.87 +/- 0.19 in GP, 1.02 +/- 0.13 in DST). Administration of unlabeled raclopride resulted in similar reductions of [11C] PHNO V3'' and [11C]raclopride V3'' in both the GP and the DST. This observation demonstrated that the [11C]PHNO binding in the GP was specific to D2-like receptors. To evaluate the respective contribution of D3 and D2 receptors to the binding potential (BP) of [11C]PHNO and [11C]raclopride, experiments were carried out with the selective D3 partial agonist 1-(4(2-Napthoylamino)butyl)-4-(2-methoxyphenyl)-1A-piperazine HCL (BP897). BP897 reduced [11C]raclopride V3'' by 29% +/- 9%, 19% +/- 8%, and 10% +/- 7% in GP, VST, and DST, respectively, a result consistent with expectation from postmortem studies (D3/D2 ratio in GP > VST > DST). BP897 reduced [11C]PHNO V3'' by 57% +/- 11%, 30% +/- 11%, and 13% +/- 8% in GP, VST, and DST, respectively, indicating that the D3 receptor contribution to [11C]PHNO signal is higher than that of [11C]raclopride. From these experiments we conclude that [11C]PHNO is a D3 preferring agonist, and that this property explains the high GP signal not observed with [11C]raclopride or [11C]NPA. This property might contribute to its higher vulnerability to endogenous DA compared to [11C]raclopride and [11C]NPA.

Objective: Reliable, uniform fat suppression is important. Multiple approaches currently exist, many of which suffer from either suboptimal signal-to-noise ratio (SNR), or the inability to obtain consistent fat suppression around the ankle joint. Our purpose was to test iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method in combination with fast spin-echo imaging, which is able to achieve reliable high SNR images with uniform fat-water separation., Subjects and Methods: We compared IDEAL fast spin-echo with conventional fat-suppressed fast spin-echo imaging in 33 ankles in 32 patients. Quantitative measurements of SNR and contrast-to-noise ratio efficiency were made, and qualitative diagnostic image quality and fat-suppression scores were determined., Results: We found that the SNR efficiency for both cartilage and fluid was similar for both techniques, and fluid/cartilage contrast-to-noise ratio efficiency was higher with IDEAL fast spin-echo imaging. Fat suppression and diagnostic quality scores using the IDEAL method were superior (p < 0.01) to fat-suppressed fast spin-echo imaging., Conclusion: IDEAL fast spin-echo imaging is a promising technique for MRI of the ankle.

The melt-state viscoelastic properties of exfoliated in situ polymerized and intercalated solution-blended polystyrene (PS) and organically modified montmorillonite nanocomposites were investigated and compared. The PS nanocomposites prepared by nitroxide-mediated polymerization (NMP) exhibit a stable exfoliated structure whereas the PS nanocomposites prepared by solution mixing exhibit an intercalated structure. The linear viscoelastic properties were strongly correlated with the dispersion state of the nanocomposites. On the other hand, the non-linear oscillatory shear properties exhibited shear thinning character and were consistent with the weak interactions between the polymer and the layered silicate.

Objective: To compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5 T and a 3.0 T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences., Methods: Both knees of five volunteers were scanned at 1.5 T and at 3.0 T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements., Results: For 3D-SPGR, cartilage SNR efficiencies at 3.0 T increased compared to those at 1.5 T by a factor of 1.83 (range: 1.40-2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81-2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95-2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5 T by a factor of 2.12 (range: 1.75-2.47), for FS-SSFP by a factor 2.11 (range: 1.58-2.80) and for Dixon SSFP by a factor 2.39 (range 2.09-2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28 mm., Conclusion: Articular cartilage imaging of the knee on a 3.0 T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5 T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5 T and 3.0 T scanners or between the three different sequences.

There is increasing evidence to suggest that adenosine receptors can modulate the function of cells involved in the immune system. For example, human dendritic cells derived from blood monocytes have recently been described to express functional adenosine A1, A2A and A3 receptors. Therefore, in the present study, we have investigated whether the recently established murine dendritic cell line XS-106 expresses functional adenosine receptors. The selective adenosine A3 receptor agonist 1-[2-chloro-6[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxy-N-methyl-beta-D-ribofuranuronamide (2-Cl-IB-MECA) inhibited forskolin-mediated [3H]cyclic AMP accumulation and stimulated concentration-dependent increases in p42/p44 mitogen-activated protein kinase (MAPK) phosphorylation. The selective adenosine A2A receptor agonist 4-[2-[[-6-amino-9-(N-ethyl-beta-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzene-propanoic acid (CGS 21680) stimulated a robust increase in [3H]cyclic AMP accumulation and p42/p44 MAPK phosphorylation. In contrast, the selective adenosine A1 receptor agonist CPA (N6-cyclopentyladenosine) did not inhibit forskolin-mediated [3H]cyclic AMP accumulation or stimulate increases in p42/p44 MAPK phosphorylation. These observations suggest that XS-106 cells express functional adenosine A2A and A3 receptors. The non-selective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) inhibited lipopolysaccharide-induced tumour necrosis factor-alpha (TNF-alpha) release from XS-106 cells in a concentration-dependent fashion. Furthermore, treatment with Cl-IB-MECA (1 microM) or CGS 21680 (1 microM) alone produced a partial inhibition of lipopolysaccharide-induced TNF-alpha release (when compared to NECA), whereas a combination of both agonists resulted in the inhibition of TNF-alpha release comparable to that observed with NECA alone. Treatment of cells with the adenosine A2A receptor selective antagonists 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5ylamino]ethyl)phenol (ZM 241385; 100 nM) and 5-amino-2-(2-furyl)-7-phenylethyl-pyrazolo[4,3-e]-1,2,4-triazolo[1,5c]pyrimidine (SCH 58261; 100 nM) and the adenosine A3 receptor selective antagonist N-[9-chloro-2-(2-furanyl)[1,2,4]-triazolo[1,5-c]quinazolin-5-benzeneacetamide (MRS 1220; 100 nM) partially blocked the inhibitory effects of NECA on lipopolysaccharide-induced TNF-alpha release. Combined addition of MRS 1220 and SCH 58261 completely blocked the inhibitory effects of NECA on lipopolysaccharide-induced TNF-alpha release. In conclusion, we have shown that the mouse dendritic cell line XS-106 expresses functional adenosine A2A and A3 receptors, which are capable of modulating TNF-alpha release.

To study the influence of psychosocial resources on psychological recovery after heart transplantation, 28 patients were surveyed during their hospitalization after transplant surgery and 6 months posttransplantation. Scales from the Coping With Serious Illness Battery were used to measure psychosocial resources (social support and personal control) and psychological and functional outcomes. Psychosocial resources assessed during hospitalization were associated with recovery outcomes at 6 months posttransplantation. Personal control was positively correlated with optimism, well-being, and satisfaction with life (r = .41 to .49) and negatively correlated with anger (r = -.57) and depression (r = -.52). Social support network helpfulness and attachment with others were correlated with psychological outcomes (r = .41 to .59) and functional outcome (r = .42 to .47). Efforts directed toward enhancing perceptions of personal control, social support network helpfulness, and attachment may be useful for promoting psychosocial recovery.

Heart failure, especially caused by systolic dysfunction, is the most common cause of hospitalization in the elderly population and the annual expenditure required for its management is at least $10 billion. The critical care nurse can play an active role in recognizing the differences between systolic and diastolic dysfunction, and teaching the patient and family that improper management or underuse of therapies can lead to disease progression.

Objective: Treatment of iatrogenic femoral artery pseudoaneurysms with thrombin injection has been reported as an efficacious and safe procedure. The major risk of this procedure is distal limb ischemia from thrombosis, resulting from thrombin escape. The cumulative average dose of thrombin reported in the literature is approximately 1100 U per patient. Minimizing the thrombin dose may reduce the risks of the procedure. This study reports our experience with low-dose thrombin injection for the treatment of pseudoaneurysms., Materials and Methods: Twenty-three patients with 26 postcatheterization femoral pseudoaneurysms were administered thrombin injection with color-flow Doppler sonographic guidance. Pseudoaneurysm volume ranged from 1 to 41 cm(3) with an average of 6.7 cm(3) and a median of 4 cm(3). Two patients received therapeutic doses of IV heparin for anticoagulation. When possible, the neck of the pseudoaneurysm was occluded during the injection to promote stagnation and prevent thrombin leakage. Sonographic follow-up was routinely performed after 24 hr., Results: An average dose of 192 U of thrombin was used (range, 50-450 U), and time to coagulation ranged from 10 to 60 sec. All 26 pseudoaneurysms were successfully thrombosed, although one required repeated treatment because of recanalization noted at 1-day follow-up. There were no complications., Conclusion: Doses of thrombin at an average of fivefold lower than previously reported were effective in the treatment of 26 iatrogenic femoral pseudoaneurysms, even in the presence of anticoagulation. This experience shows that a much smaller dose of a potentially dangerous medication can achieve the same efficacy as previously used higher doses.

Important advances in rapid magnetic resonance (MR) imaging technology and its application to cardiovascular imaging have been made during the past decade. High-field-strength clinical magnets, high-performance gradient hardware, and ultrafast pulse sequence technology are rapidly making the vision of a comprehensive "one-stop shop" cardiac MR imaging examination a reality. This examination is poised to have a significant effect on the management of coronary artery disease by means of assessment of wall motion with tagging and pharmacologic stress testing, evaluation of the coronary microvasculature with perfusion imaging, and direct visualization of the coronary arteries with MR coronary angiography. This article reviews current state-of-the-art pulse sequence technology and its application to the evaluation of ischemic heart disease by means of MR tagging with dobutamine stress testing, MR perfusion imaging, and MR coronary angiography. Cutting edge areas of research in coil design and exciting new areas of metabolic and oxygen level-dependent imaging are also explored.

Hypertension has been linked to many diseases, including coronary heart disease, myocardial infarction, renal failure, and stroke. Treatment involves lowering blood pressure (BP) and altering the sequelae. Medications such as beta-blockers reduce BP and prevent complications such as ventricular remodeling, endothelial impairment, and renal insufficiency. This article describes the pathophysiology of hypertension, complications, and theories of primary hypertension. Critical care nurses will learn about the pharmacodynamics and latest research on beta-blocker therapy and critical decision making for patients taking these medications.

The purpose of this study was to evaluate the psychosocial impact of heart transplantation on spouses and compare the adjustment of spouses and their partners. Data were collected from 51 couples prior to transplant and 12 months posttransplant. The Psychosocial Adjustment to Illness Scale (PAIS) was used to measure adjustment in seven domains. Prior to the transplant, spouses experienced profound psychosocial distress related to their partner's illness. From pretransplant to posttransplant, PAIS total score decreased (lower scores indicate better adjustment) for spouses (M = 42, SD = 16, vs. M = 26, SD = 13). Spouses showed improvement in all domains. Posttransplant, patients' and spouses' PAIS total scores (overall adjustment) were not significantly different. Spouses reported more psychological distress than patients; patients reported more problems than spouses in vocational and domestic function. Study findings highlight the importance of sensitivity in the clinical setting to the distinct psychosocial needs of spouses.

The development of genetically modified "whole" tumor cell vaccines for cancer therapy relies on the efficient transduction and expression of genes by vectors. In the present study, we have used a disabled infectious single cycle-herpes simplex virus 2 (DISC-HSV-2) vector constructed to express cytokine or marker genes upon infection. DISC-HSV-2 is able to infect a wide range of tumor cells and efficiently express the beta-galactosidase reporter gene, granulocyte-macrophage colony-stimulating factor (GM-CSF), or IL-2 genes. Gene expression occurred rapidly after infection of tumor cells, and the level of production of the gene product (beta-galactosidase, GM-CSF, or IL-2) was shown to be both time-and dose-dependent. Vaccination with irradiated DISC-mGM-CSF or DISC-hIL-2-infected murine tumor cells resulted in greatly enhanced immunity to tumor challenge with live parental tumor cells compared with control vaccines. When used therapeutically to treat existing tumors, vaccination with irradiated DISC-mGM-CSF-infected tumor cells significantly reduced the incidence and growth rates of tumors when administered locally adjacent to the tumor site, providing up to 90% protection. The prophylactic and therapeutic efficacy of DISC-mGM-CSF-infected cells was shown initially using a murine renal cell carcinoma model (RENCA), and the results were confirmed in two additional murine tumor models: the M3 melanoma and 302R sarcoma. Therapy with DISC-infected RENCA "whole" cell vaccines failed to reduce the incidence or growth of tumor in congenitally T-cell deficient (Nu+/Nu+) mice or mice depleted of CD4+ and/or CD8+ T-lymphocytes, confirming that both T-helper and T-cytotoxic effector arms of the immune response are required to promote tumor rejection. These preclinical results suggest that this "novel" DISC-HSV vector may prove to be efficacious in developing genetically modified whole-cell vaccines for clinical use.

Beta-blockers are effective agents for secondary prevention post-myocardial infarction (MI). They have antiarrhythmic, anti-ischemic, and antihypertensive effects that decrease morbidity and mortality in patients after an MI. Critical care nurses can play an active role in recognizing those patients, especially high-risk individuals, who may benefit from beta-blocker therapy.

Recent evidence has shown that homocysteine, a sulfur-containing amino acid, is a risk factor for cardiovascular disease (CVD) and may be one of the missing links in explaining the persistently high mortality associated with CVD. Critical care nurses need to be aware of the pathophysiology, treatment, and research regarding hyperhomocysteinemia and incorporate this knowledge into clinical practice.

Purpose: To determine whether myocardial arterial perfusion and oxygen concentration can be quantified simultaneously from the same images by using spin labeling and the blood oxygenation level-dependent (BOLD) effect with fast spin-echo (SE) imaging., Materials and Methods: A T2-weighted fast SE pulse sequence was written to image isolated, arrested, blood-perfused rabbit hearts (n = 6) at 4.7 T. Perfusion images with intensity in units of milliliters per minute per gram that covered the entire left ventricle with 0.39 x 0.39 x 3.00-mm resolution were obtained in less than 15 minutes with a 32-fold reduction in imaging time from that of a previous study. Estimates of oxygen concentration were made from the same images acquired for calculation of perfusion images., Results: Estimates of regional myocardial oxygen content could be made from the perfusion images; this demonstrated the feasibility of three-dimensional calculation of regional oxygen consumption, which requires concomitant measurement of both oxygen content and flow. Fast SE imaging was shown to be as sensitive to hemoglobin desaturation as standard SE imaging. Perfusion abnormalities and oxygen deficits were easily identified and verified qualitatively with gadopentetate dimeglumine on both perfusion and BOLD images obtained after coronary arterial ligation., Conclusion: T2-weighted fast SE imaging combined with perfusion-sensitive spin labeling can be used to measure myocardial arterial perfusion and oxygen concentration. This provides the groundwork for calculation of regional myocardial oxygen consumption.

To investigate the effects of water exchange on quantification of perfusion, data were acquired in isolated hearts (n = 11) and used to develop a model of exchange. Myocardial T1 was measured 3 times/sec during step changes in concentration of intravascular (polylysine-gadolinium-diethylene-triamine-pentaacetic acid) and extracellular (gadoteridol) agents. For the intravascular agent, the change in 1/T1 (deltaR1) was lower than predicted by fast exchange (2.7+/-0.5 vs. 7.8 sec(-1), respectively), and suggested an intra-extravascular exchange rate of 3 Hz. For the extracellular agent, contrast kinetics were similar to those of similarly sized molecules (wash-in time constant 38+/-5 sec), and the data suggested fast interstitial-cellular exchange. Modeling showed that perfusion is underestimated for both agents if exchange is ignored, although the relationships of measured to actual perfusion were monotonic. We conclude that myocardial water exchange strongly affects first-pass enhancement but that ignoring the effects of exchange may still provide reasonable estimates of regional perfusion differences.

Cardiac magnetic resonance imaging requires high temporal resolution to resolve motion and contrast uptake with low total scan times to avoid breathing artifacts. While spoiled gradient echo (SPGR) imaging is robust and reproducible, it is relatively inefficient and requires long breath-holds to acquire high time resolution movies of the heart. Echo planar imaging (EPI) is highly efficient with excellent signal-to-noise ratio (SNR) behavior; however, it is particularly difficult to use in the heart because of its sensitivity to chemical shift, susceptibility, and motion. EPI may also require reference scans, which are used to measure hardware delays and phase offsets that cause ghosting artifacts; these reference scans are more difficult and less reliable in the heart. Consequently, a hybrid EPI/SPGR sequence is proposed for application to rapid cardiac imaging. A detailed optimization of SNR and echo train length for multi-echo sequences is presented. It is shown that significant reductions in total scan time are possible while maintaining good image quality. This will allow complete motion sampling of the entire heart in one to three breath-holds, necessary for MR cardiac dobutamine stress testing. Improved speed performance also permits sampling of three to six slices every heartbeat for bolus injection perfusion studies.

Interleaved echo-planar imaging (EPI) is an ultrafast imaging technique important for applications that require high time resolution or short total acquisition times. Unfortunately, EPI is prone to significant ghosting artifacts, resulting primarily from system time delays that cause data matrix misregistration. In this work, it is shown mathematically and experimentally that system time delays are orientation dependent, resulting from anisotropic physical gradient delays. This analysis characterizes the behavior of time delays in oblique coordinates, and a new ghosting artifact caused by anisotropic delays is described. "Compensation blips" are proposed for time delay correction. These blips are shown to remove the effects of anisotropic gradient delays, eliminating the need for repeated reference scans and postprocessing corrections. Examples of phantom and in vivo images are shown.

Background: Microvascular obstruction within an area of myocardial infarction indicates worse functional recovery and a higher risk of postinfarction complications. After prolonged coronary occlusion, contrast-enhanced MRI identifies myocardial infarction as a hyperenhanced region containing a hypoenhanced core. Because the time course of microvascular obstruction after infarction/reperfusion is unknown, we examined whether microvascular obstruction reaches its full extent shortly after reperfusion or shows significant progression over the following 2 days., Methods and Results: Seven dogs underwent 90-minute balloon occlusion of the left anterior descending coronary artery (LAD) followed by reflow. Gadolinium-DTPA-enhanced MRI performed at 2, 6, and 48 hours after reperfusion was compared with radioactive microsphere blood flow (MBF) measurements and myocardial staining to define microvascular obstruction (thioflavin S) and infarct size (triphenyltetrazolium chloride, TTC). The MRI hypoenhanced region increased 3-fold during 48 hours after reperfusion (3.2+/-1.8%, 6.7+/-4.4%, and 9.9+/-3.2% of left ventricular mass at 2, 6, and 48 hours, respectively, P<0.03) and correlated well with microvascular obstruction (MBF <50% of remote region, r=0.99 and thioflavin S, r=0.93). MRI hyperenhancement also increased (21.7+/-4.0%, 24.3+/-4.6%, and 28.8+/-5.1% at 2, 6, and 48 hours, P<0.006) and correlated well with infarct size by TTC (r=0.92). The microvascular obstruction/infarct size ratio increased from 13.0+/-4.8% to 22.6+/-8.9% and to 30.4+/-4.2% over 48 hours (P=0.024)., Conclusion: The extent of microvascular obstruction and the infarct size increase significantly over the first 48 hours after myocardial infarction. These results are consistent with progressive microvascular and myocardial injury well beyond coronary occlusion and reflow.

Angiotensin-converting enzyme (ACE) inhibitors have been shown to be effective agents that improve the sequelae of left ventricular remodeling following a myocardial infarction. The critical care nurse can play an active role in recognizing those patients who will benefit from ACE inhibitor therapy.

Adiabatic pulses, although useful in generating uniform spin nutation in the presence of inhomogeneous B1 fields, are limited for NMR imaging applications due to the lack of slice-selective excitation capability. Selective excitation techniques using gradient modulation have been introduced; however, present methods require either a minimum of two excitations or eight adiabatic segments. Here, a scheme is presented that allows single-shot, arbitrary flip-angle, and slice-selective excitation with only four adiabatic half-passage segments. The technique is demonstrated via computer simulation and experimental tests on a phantom. Furthermore, issues associated with the implementation of these gradient-modulated adiabatic pulses are discussed.

Cardiac echo-planar imaging suffers invariably from regions of severe distortion and T*2 decay in the myocardium. The purpose of this work was to perform local measurements of T*2 and field inhomogeneities in the myocardium and to identify the sources of focal signal loss and distortion. Field inhomogeneity maps and T*2 were measured in five normal volunteers in short-axis slices spanning from base to apex. It was found that T*2 ranged from 26 ms (SD = 7 ms, n = 5) to 41 ms (SD = 11 ms, n = 5) over most of the heart, and peak-to-peak field inhomogeneity differences were 71 Hz (SD = 14 Hz, n = 5). In all hearts, regions of severe signal loss were consistently adjacent to the posterior vein of the left ventricle; T*2 in these regions was 12 ms (SD = 2 ms, n = 5), and the difference in resonance frequency with the surrounding myocardium was 70-100 Hz. These effects may be caused by increased magnetic susceptibility from deoxygenated blood in these veins.

Women have different needs than men after a myocardial infarction. Therefore, nursing care for women should be based on current research rather than research based on findings using the "male model." This article examines research on the prognosis for women after a myocardial infarction and recommends practice changes for the critical care nurse based on these findings.