Left atrial volume quantification using cardiac MRI in atrial fibrillation: comparison of the Simpson's method with biplane area-length, ellipse, and three-dimensional methods.

PURPOSE: Left atrial volume is an important predictor of future arrhythmias, and it can be assessed by several different methods. Simpson's method is well accepted as a reference standard, although no standardization exists for cardiac magnetic resonance (CMR). We aimed to compare the estimations of left atrial volumes obtained by the Simpson's method with three other methods. MATERIALS AND METHODS: Eighty-one consecutive patients referred for CMR imaging between February 2007 and May 2010 were included in the study (47 males; mean age, 59.4±11.5 years; body mass index, 26.3±3.7 kg/m(2)). Left atrial volume measurements were performed using the Simpson's, biplane area-length, ellipse, and three-dimensional methods. Results were correlated using a Bland-Altman plot and linear regression models and compared by two-tailed paired-sample t tests. Reader variability was also calculated. RESULTS: Left atrial volume measurements using the biplane area-length technique showed the best correlation with Simpson's method (r=0.92; P < 0.001). Quantification values using the ellipse and three-dimensional methods were significantly different than values obtained using the Simpson's method (P < 0.05, for both). All methods showed excellent observer reliability (intra-class correlation coefficient >0.99). CONCLUSION: The biplane area-length method can be used for left atrial volume measurement when the Simpson's method cannot be performed. If these two methods are not feasible, then all methods are highly reproducible and can be used, but should not be used interchangeably for follow-up studies.

Assessment of intra-arterial injected autologous bone marrow mononuclear cell distribution by radioactive labeling in acute ischemic stroke.

OBJECTIVE: To evaluate the feasibility of monitoring the autologous mononuclear bone marrow (ABMMN) cells implanted into the brain after acute ischemic stroke by the technique of labeling with Tc-99m-HMPAO. CASE REPORT: A 37-year-old man presented with aphasia, right-side hypoesthesia, and right homonymous hemianopsia after an acute ischemic stroke of the left middle cerebral artery. He was included in an autologous bone marrow mononuclear cell-based therapy research protocol about the safety of intra-arterial autologous bone marrow mononuclear cell transplantation for acute ischemic stroke. Nine days after the stroke he received 3.0 x 10(7) ABMMN cells delivered into the left cerebral middle artery via a balloon catheter. Approximately 1% of these cells were labeled with 150 MBq (4 mCi) Tc-99m by incubation with hexamethylpropylene amine oxime (HMPAO). RESULTS: Brain perfusion images with Tc-99m ECD demonstrated hypoperfusion in the left temporal and parietal regions. The perfusion brain images were compared with tomographic views of the brain obtained 8 hours after ABMMN-labeled cell delivery, revealing intense accumulation of the ABMMN-labeled cells in the ipsilateral hemisphere. A whole-body scan was done and showed left brain, liver, and spleen uptake. CONCLUSIONS: Our results showed that Tc-99m HMPAO can be used to label ABMMN cells for in vivo cell visualization, and that brain SPECT imaging with labeled ABMMN cells is a feasible noninvasive method for studying the fate of transplanted cells in vivo. Additionally, our findings demonstrate the localization of these intra-arterially injected cells.

Gastrointestinal bleeding diagnosed by red blood cell scintigraphy in a patient with aortic stenosis: a case of Heyde syndrome.

The authors report a case of small bowel bleeding diagnosed by Tc-99m-labeled red blood cell (RBC) scintigraphy during the postoperative period after aortic valve replacement. There is a relationship between aortic valve stenosis and gastrointestinal bleeding in elderly patients, called Heyde syndrome. The described patient had chronic anemia that worsened after surgery. RBC scintigraphy localized the source of bleeding from jejunal angiodysplasia confirmed by mesenteric angiography. This case illustrates the diagnostic information provided by RBC scintigraphy in this syndrome.