Improved fat water separation with water selective inversion pulse for inversion recovery imaging in cardiac MRI

Purpose:

To develop an improved chemical shift‐based water‐fat separation sequence using a water‐selective inversion pulse for inversion recovery 3D contrast‐enhanced cardiac magnetic resonance imaging (MRI).

Materials and Methods:

In inversion recovery sequences the fat signal is substantially reduced due to the application of a nonselective inversion pulse. Therefore, for simultaneous visualization of water, fat, and myocardial enhancement in inversion recovery‐based sequences such as late gadolinium enhancement imaging, two separate scans are used. To overcome this, the nonselective inversion pulse is replaced with a water‐selective inversion pulse. Imaging was performed in phantoms, nine healthy subjects, and nine patients with suspected arrhythmogenic right ventricular cardiomyopathy plus one patient for tumor/mass imaging. In patients, images with conventional turbo‐spin echo (TSE) with and without fat saturation were acquired prior to contrast injection for fat assessment. Subjective image scores (1 = poor, 4 = excellent) were used for image assessment.

Results:

Phantom experiments showed a fat signal‐to‐noise ratio (SNR) increase between 1.7 to 5.9 times for inversion times of 150 and 300 msec, respectively. The water‐selective inversion pulse retains the fat signal in contrast‐enhanced cardiac MR, allowing improved visualization of fat in the water‐fat separated images of healthy subjects with a score of 3.7 ± 0.6. Patient images acquired with the proposed sequence were scored higher when compared with a TSE sequence (3.5 ± 0.7 vs. 2.2 ± 0.5, P < 0.05).

Conclusion:

The water‐selective inversion pulse retains the fat signal in inversion recovery‐based contrast‐enhanced cardiac MR, allowing simultaneous visualization of water and fat. J. Magn. Reson. Imaging 2013;37:484–490. © 2012 Wiley Periodicals, Inc.     

Allorecognition and effector pathways of islet allograft rejection in normal versus nonobese diabetic mice

Islet transplantation is becoming an accepted therapy to cure type I diabetes mellitus. The exact mechanisms of islet allograft rejection remain unclear, however. In vivo CD4(+) and CD8(+) T cell-depleting strategies and genetically altered mice that did not express MHC class I or class II antigens were used to study the allorecognition and effector pathways of islet allograft rejection in different strains of mice, including autoimmunity-prone nonobese diabetic (NOD) mice. In BALB/c mice, islet rejection depended on both CD4(+) and CD8(+) T cells. In C57BL/6 mice, CD8(+) T cells could eventually mediate islet rejection by themselves, but they produced rejection more efficiently with help from CD4(+) T cells stimulated through either the direct or indirect pathway. In C57BL/6 mice, CD4(+) T cells alone caused islet rejection when only the direct pathway was available but not when only the indirect pathway was available. In contrast, in NOD mice, CD4(+) T cells alone, with only the indirect pathway, could mediate islet and cardiac allograft rejection. These findings indicate that different mouse strains can make use of different pathways for T cell-mediated rejection of islet allografts. In addition, they demonstrate that NOD mice, which develop autoimmunity and are known to be resistant to tolerance induction, have an unusually powerful CD4(+) cell indirect mechanism that can cause rejection of both islet and cardiac allografts. These data shed light on the mechanisms of islet allograft rejection in different responder strains, including those with autoimmunity.     

Two-step surgery for synchronous bilobar liver metastases from digestive endocrine tumors: a safe approach for radical resection

OBJECTIVE: We describe the early and distant results of a 2-step surgical strategy that enables complete resection in selected patients with primary digestive endocrine tumors (DET) and synchronous bilobar liver metastases (LM). BACKGROUND: Frequent synchronous and bilobar liver involvement limits indications of surgery in LM from DET. STUDY DESIGN: From 1996 to 2004, of 41 patients with synchronous bilobar LM from DET, 23 (56%) were selected for 2-step surgery. The first step included resection of the primary tumor and limited (nonanatomic) resection of left LM (segments 1-4) associated with a right portal vein ligation. After 8 weeks, following hypertrophy of the cleared left liver, a right or extended right hepatectomy was planned. RESULTS: At the first step, all primary tumors (bowel = 12, distal pancreas = 10, rectal = 1) were resected and LM were resected in 20 patients (87%). One patient did not have second-step due to tumor progression. The second step (n = 19; 83%) was performed after a median interval of 8 weeks (range, 6-13) and a 54 +/- 21% mean left liver hypertrophy rate. Postoperatively, 4 (17%) and 4 (21%) patients developed nonlethal complications and the median hospital stay was 11 (range, 7-26) and 13 (range, 9-17) days after the first and the second step, respectively. The median number of resected LM was 4 (range, 1-9) and 7 (range, 4-17), respectively. With a median follow-up of 64 months (range, 6-122), of the 19 patients who had complete 2-step surgery, all except one are alive. The 2-, 5-, and 8-year Kaplan-Meier overall and disease-free survival rates were 94%, 94%, 79% and 85%, and 50% and 26%, respectively. CONCLUSIONS: This 2-step surgery approach enables complete resection with no mortality, acceptable morbidity, and good long-term survival in selected patients with synchronous bilobar LM from DET.     

The preventative analgesic effect of preincisional peritonsillar infiltration of two low doses of ketamine for postoperative pain relief in children following adenotonsillectomy. A randomized, double-blind, placebo-controlled study

Background:  In literature, the use of ketamine for the preventative analgesia in the management of postoperative pain is controversial. The purpose of the present study was the clinical assessment of the efficacy of preincisional peritonsillar infiltration of two doses of ketamine on postoperative pain relief compared with peritonsillar saline in children undergoing adenotonsillectomy.
Methods/materials:  Seventy-five ASA physical status I and II patients, aged 3–12 years, scheduled for adenotonsillectomy were enrolled in this randomized, double-blind, placebo-controlled study. Patients were divided into three groups of 25 each and received a local peritonsillar infiltration of 0.9% saline (group S), ketamine 0.5 mg·kg⁻¹ (group K1), or ketamine 1 mg·kg⁻¹ (group K2). All medications were 2 ml in volume which was applied 1 ml per tonsil 3 min prior to tonsillectomy. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and Wilson sedation scale were used to evaluate pain levels and sedative conditions, respectively.
Results:  Group S had significantly higher CHEOPS scores than group K1 and K2. Both K1 and K2 groups had comparable scores, which were not statistically significant ( P  > 0.05). During 24 h after surgery, 16 patients in group S and no patients in groups K1 or K2 needed analgesics ( P  <   0.001).
Conclusions:  A 0.5 or 1 mg·kg⁻¹ dose of ketamine given at approximately 3 min before surgery by peritonsillar infiltration provides efficient pain relief during 24 h after surgery without side-effects in children undergoing adenotonsillectomy.     

Immunomodulation by mesenchymal stem cells: a potential therapeutic strategy for type 1 diabetes

Mesenchymal stem cells (MSCs) are pluripotent stromal cells that have the potential to give rise to cells of diverse lineages. Interestingly, MSCs can be found in virtually all postnatal tissues. The main criteria currently used to characterize and identify these cells are the capacity for self-renewal and differentiation into tissues of mesodermal origin, combined with a lack in expression of certain hematopoietic molecules. Because of their developmental plasticity, the notion of MSC-based therapeutic intervention has become an emerging strategy for the replacement of injured tissues. MSCs have also been noted to possess the ability to impart profound immunomodulatory effects in vivo. Indeed, some of the initial observations regarding MSC protection from tissue injury once thought mediated by tissue regeneration may, in reality, result from immunomodulation. Whereas the exact mechanisms underlying the immunomodulatory functions of MSC remain largely unknown, these cells have been exploited in a variety of clinical trials aimed at reducing the burden of immune-mediated disease. This article focuses on recent advances that have broadened our understanding of the immunomodulatory properties of MSC and provides insight as to their potential for clinical use as a cell-based therapy for immune-mediated disorders and, in particular, type 1 diabetes.     

Results of surgery for irreversible moderate to severe mitral valve regurgitation secondary to myocardial infarction.

OBJECTIVE: Moderate to severe irreversible mitral regurgitation secondary to myocardial infarction is an independent risk factor for reduced long-term survival. Late effects of correction of mitral incompetence concomitant with coronary artery bypass grafting (CABG) are less well known and the choice of mitral valve procedure is still debated. METHODS: From 1988 to 1998, 93 consecutive patients (mean age 63+/-9 years) were treated for moderate to severe irreversible mitral regurgitation secondary to myocardial infarction; 84 were in NYHA functional class III-IV and 19 were in cardiogenic shock. Thirty-seven patients underwent emergency surgery. Perioperative intraaortic balloon pump (IABP) was necessary in 33 patients. Follow-up ranged from 6 months to 12 years (mean 51 months+/-41). RESULTS: Mitral valve was repaired in 30 patients and replaced in 63. Replacement was preferably performed in patients with major displacement of papillary muscle and in patients with acute papillary muscle rupture. CABG (3.4 distal anastomoses) was performed in all patients and was complete in 92%. Early mortality was 15% (14/93). Multivariable analysis identified need for IABP (P=0.005) and COPD (P=0.02) as risk factors for early death. Emergency surgery had only a trend (P=0.15) for increased mortality; age, low ejection fraction, repair vs. replacement had no influence. Actuarial survival rates at 1, 5 and 10 years were 81, 65 and 56%, respectively. Late survival was similar in patients with replacement or repair (P=0.46). At last follow-up, all but one patient were in NYHA functional class I or II. CONCLUSIONS: Combined mitral valve procedure and myocardial revascularization, as complete as possible, for moderate to severe mitral regurgitation secondary to myocardial infarction achieve satisfactory early and late outcome despite the increased operative mortality. Acute papillary muscle rupture, severe restriction of the mitral valve by major displacement of the papillary muscle are better managed by valve replacement.     

Comparative study of functional responses and morphometric state of distal radial arteries in male and female

BACKGROUND: Differences can exist in terms of physiology and morphology of blood vessels on the basis of gender. Radial artery is now considered to be the second choice for coronary artery bypass grafting. However, there is a lack of comparative studies on the function and morphometery of radial arteries in female and male patients. METHODS: Radial arteries from 9 female and 9 male patients undergoing coronary artery bypass grafting were used to compare the effects of vasoconstrictors, noradrenaline and 5-hydroxytryptamine, as well as the influence of endothelium-dependent (with methacholine) and endothelium-independent (with sodium nitroprusside) relaxations. Furthermore, morphomteric measurements of smooth muscle thickness, lumen perimeter, lumen area, and intima area (including plaque) of distal radial arteries from female and male patients were also made. RESULTS: Radial arteries from female patients when compared to male patients were significantly more sensitive to the actions of noradrenaline, and somewhat more sensitive towards the actions of 5-hydroxytryptamine. However, no significant differences were found between the relaxant effects of methacholine in radial arteries of female and male patients. In contrast, radial arteries from female patients when compared to male patients were significantly less sensitive to the relaxant effects of sodium nitroprusside. Morphometric measurements of blood vessels from female and male patients revealed that vessels obtained from female patients had a smaller lumen area and perimeter than vessels from male patients. In contrast, there were no significant differences between tunica intima area (including plaque area) or smooth muscle thickness in radial arteries of female patients when compared to male patients. However, the radial arteries from female patients had a significantly greater ratio of tunica intima area (including plaque) to lumen area when compared with radial arteries from male patients. CONCLUSIONS: Differences exist between the functional behavior and morphometery of radial arteries of female and male patients. It is possible that postbypass, radial artery graft may show different characteristics in female versus male patients.     

Extent of liver resection influences the outcome in patients with cirrhosis and small hepatocellular carcinoma

BACKGROUND: The long-term outcome after resection of hepatocellular carcinoma (HCC) is influenced by parameters related to the tumor and the underlying liver disease. However, the extent of the resection, which can be limited or anatomical (including the tumor and its portal territory), is controversial. METHODS: Among 64 Child-Pugh A patients with cirrhosis who underwent curative liver resection for small HCC (< or = 4 cm) between 1990 and 1996, 34 patients underwent limited resection with a margin width of at least 1 cm, and 30 patients underwent anatomic resection of at least 1 liver segment with complete removal of the portal area containing the tumor. The 2 groups were comparable in terms of epidemiologic and pathologic parameters. The major end points were: (1) in-hospital mortality and morbidity; (2) overall and disease-free survival; and (3) rate and topography of recurrence. RESULTS: The 30-day mortality (6% vs 7%) and morbidity (52% vs 47%) rates after limited and anatomic liver resection were not statistically different. The 5- and 8-year overall survival rates after limited versus anatomic resection were, respectively, 35% versus 54% (P <.05) and 6% versus 45% (P <.05). The 5- and 8-year disease-free survival rates were, respectively, 26% versus 45% and 0% versus 21% (P <.05). Local recurrence was more frequently observed after limited resections than after anatomic resections (50% vs 10%, P <.05). CONCLUSIONS: In patients with cirrhosis and a small HCC, anatomic resection achieves better disease-free survival than limited resection without increasing the postoperative risk. Therefore, anatomical resection should be the treatment of choice and considered as the reference surgical treatment compared with other treatments.     

Recent trends in early outcome of adult patients after heart transplantation: a single-institution review of 251 transplants using standard donor organs.

Older age, prior transplantation, pulmonary hypertension, and mechanical support are commonly seen in current potential cardiac transplant recipients. Transplants in 436 consecutive adult patients from 1994 to 1999 were reviewed. There were 251 using standard donors in 243 patients (age range 18-69 years). To emphasize recipient risk, 185 patients who received a nonstandard donor were excluded from analysis. The indications for transplant were ischemic heart disease (n = 123, 47%), dilated cardiomyopathy (n = 82, 32%), and others (n=56, 21%). One hundred and forty-nine (57%) recipients were listed as status I; 5 and 6% were supported with an intra-aortic balloon and an assist device, respectively. The 30-d survival and survival to discharge were 94.7 and 92.7%, respectively; 1-year survival was 89.1%. Causes of early death were graft failure (n = 6), infection (n = 4), stroke (n = 4), multiorgan failure (n = 3) and rejection (n = 2). Predictors were balloon pump use alone (OR= 11.4, p =0.002), pulmonary vascular resistance > 4 Wood units (OR = 5.7, p = 0.007), pretransplant creatinine > 2.0 mg/dL (OR = 6.9, p = 0.004) and female donor (OR = 8.3, p = 0.002). Recipient age and previous surgery did not affect short-term survival. Heart transplantation in the current era consistently offers excellent early and 1-year survival for well-selected recipients receiving standard donors. Early mortality tends to reflect graft failure while hospital mortality may be more indicative of recipient selection.