Contrast-dose relation in first-pass myocardial MR perfusion imaging

PURPOSE: To determine the regime of linear contrast enhancement in human first-pass perfusion cardiovascular magnetic resonance (CMR) imaging to improve accuracy in myocardial perfusion quantification. MATERIALS AND METHODS: A total of 10 healthy subjects were studied on a clinical 1.5T MR scanner. Seven doses of Gd-DTPA ranging from 0.00125 to 0.1 mmol/kg of body weight (b.w.) were administered as equal volumes by rapid bolus injection (6 mL/second). Resting periods of 15 minutes were introduced after delivery of Gd doses >0.01 mmol/kg b.w. For each subject, two series of rest perfusion scans were performed using two different multislice saturation-recovery perfusion sequences. Maximum contrast enhancement and maximum upslope were obtained in the blood pool of the left ventricular (LV) cavity and in the myocardium. The range of linear contrast-dose relation was determined by linear regression analysis. RESULTS: MR signal intensity increased linearly for contrast agent concentrations up to 0.01 mmol/kg b.w. in the LV blood pool and up to 0.05 mmol/kg b.w. in the myocardium. For Gd concentrations exceeding these thresholds the signal intensity response was not linear with respect to the contrast agent dose. CONCLUSION: Quantitative evaluation of cardiac MR perfusion data needs to account for signal saturation in both the LV blood pool and the myocardium.     

Economic image compression of output documentation of the most frequent examinations in nuclear medicine

RATIONALE AND OBJECTIVES: In recent years, picture archiving and communication systems and electronic transfer of radiologic images using the digital imaging and communications in medicine file standard has become more widely employed in diagnostic radiology. It seems to be likely that nuclear medicine will be integrated within such systems. On the other hand, many departments possess older nuclear medicine equipment without digital output facilities. There is an increasing tendency to display and archive evaluated images ("save-screens," printouts) on nondedicated, inexpensive systems using file formats capable of data compression. This was the reason for examining the value of the JPEG format in this pilot study. MATERIALS AND METHODS: Fifty scanned planar bitmap images of the most frequent scintigraphic examinations (thyroid, bone, myocardium, lungs, and kidneys) were compared with JPEG format at different data compressions by two blinded observers. The visualization of details (eg, pathologic findings) is described for all these images as the visual appearance of the images and the storage capacity required. RESULTS: Relevant loss of clinical information did not occur up to compression factors of 0.75. A major decrease of subjective image quality was seen at compression factors >0.90. Compared with bitmap files, the use of these factors reduced the storage capacity required by 98% at a (JPEG-related) compression factor of 0.50, and 99% at a compression factor of 0.90. Compared with the GIF format, a reduction by 4.0-5.7 could be achieved. CONCLUSIONS: Use of the JPEG format can therefore be recommended to save costs of image transfer or archiving of standard planar scans for nuclear medical evaluation.     

Identification of sensory blockade by somatosensory and pain-induced evoked potentials

BACKGROUND: To date, the anesthesia-induced blockade of nociceptive inputs is insufficiently reflected by commercially available electroencephalographic depth-of-anesthesia monitors. The aim of the current study was to evaluate the potential of somatosensory (SSEP) and intracutaneous pain evoked (iSEP) potentials during remifentanil and propofol anesthesia as electroencephalographic indicators of the nociceptive blockade. METHODS: Ten healthy men were investigated in a double-blind crossover design during three sessions with remifentanil, propofol, and placebo administration. All dosages were increased in a step-by-step mode. SSEP and iSEP recordings were performed followed by subjective pain ratings and measurement of level of sedation (modified Observer's Assessment of Alertness and Sedation Scale). Changes from baseline in evoked potential components, pain ratings, and sedation scale were assessed by Bonferroni-Holms-corrected Wilcoxon tests. RESULTS: Pain ratings were significantly reduced by remifentanil. Sedation scale was significantly reduced by propofol. Early SSEP components were not affected by medication. The amplitudes of the long latency SSEP components increased significantly with remifentanil, decreased with propofol, and did not change with placebo. The amplitudes of long latency components of the iSEP decreased significantly with both remifentanil and propofol and did not change with placebo. CONCLUSION: Long latency components of the SSEP are differently affected by remifentanil and propofol administration. Further studies are needed to clarify whether they can serve as a specific indicator of the nociceptive blockade during anesthesia.     

Outcome of traumatic extradural haematoma in Hong Kong

AIM: Traumatic extradural haematoma (EDH) is a neurosurgical emergency and timely surgical intervention for significant EDH is the gold standard. This study aims to determine the incidence and mortality of consecutive patients with traumatic EDH admitted to the Emergency Department (ED) of Prince of Wales Hospital (PWH), a University Hospital Trauma Centre in Hong Kong. PATIENTS AND METHODS: Retrospective analysis of prospectively collected data for all consecutive trauma cases admitted through the ED during 2001-2004. EDH was diagnosed by CT in all cases. Both primary and delayed onset EDH were included, as were patients with combined EDH and other intracranial lesions (e.g. subdural haematoma). Age, sex, cause of injury, associated intracranial lesions, skull fracture, Glasgow Coma Scale, pupil reactivity, treatment, length of stay and clinical outcome were determined. RESULTS: Two thousand and two hundred and eight patients were in the trauma registry for 2001-2004. Total 1080 head injured patients; 89 patients had traumatic EDH, mean of 1.9 patients per month. Seventy (79%) patients were male, with a mean age of 37.7 years. Fifty (56%) patients were from road traffic crashes, 27 (30%) sustained falls, 10 (11%) had direct head trauma. On admission, 62 (70%) patients were GCS 13-15, 9 (10%) GCS 9-12 and 18 (20%) GCS 3-8. Sixty-six (74%) patients had a skull fracture. Thirty (34%) patients underwent neurosurgical operation. Overall, nine patients (10%) died; eight patients were GCS<8; five had bilateral fixed and dilated pupils; one had a single fixed and dilated pupil. Four patients died after neurosurgical operation, three of whom had fixed dilated pupils and were GCS 3 prior to surgery. Median length of hospital stay for survivors was 10.4 days. CONCLUSION: Survival from traumatic EDH was 90% (80/89) and 91% (73/80) of survivors had a Glasgow Outcome Score of 4 or 5 (good or moderate). The combination of bilateral fixed dilated pupils and GCS 3 suggests severe primary brain injury. Emergency evacuation of intracranial haematomas is unlikely to improve the outcome for these patients. Even in an urban environment with short prehospital times and rapid access to neurosurgery, outcome in patients who are GCS 3 following EDH is likely to be poor.     

Five year analysis of Jockey Club horse-related injuries presenting to a trauma centre in Hong Kong

BACKGROUND: Professional horse riding-related injuries have not been studied before in Hong Kong, although horse racing takes place very regularly in the territory. In addition, the equestrian events of the 2008 Beijing Olympic Games will come to Hong Kong. This study analysed the pattern of horse-related injury among patients who presented to a trauma centre in a teaching hospital in Hong Kong. METHODS: Information from the trauma centre database was analysed retrospectively. The database includes trauma patients who had sustained potentially severe injuries that warranted initial assessment and resuscitation in a trauma resuscitation room (triage category 1 or 2). Data analysed included demographic variables, causes and mechanisms of injury, anatomical injuries, anatomical and physiological trauma scores, and patient outcome. RESULTS: Between January 2001 and June 2005, 2312 trauma patients were entered into the database. Thirty-six (1.6%) patients had sustained horse-related injuries (mean age 34 years, range 17-54; male to female ratio 32:4), all whilst at work in the Jockey Club. Twenty-two patients were injured between midnight and 09:00 h. This group stayed in the resuscitation room for longer prior to admission compared with patients presenting between 09:00h and midnight (median time 127 min (interquartile range [IQR] 57-183) versus 58 min (IQR 43-83), p=0.06). Twenty-five patients fell from horseback, whilst 11 were kicked by the horse. Twenty patients had a single injury and 16 patients had multiple injuries. Eighteen patients had injuries to the thorax, abdomen, thoracolumbar spine or pelvis. Eleven patients had head, face and cervical spine injuries and 11 had limb injuries. Twenty-five patients were admitted, including four admitted to the intensive care unit (ICU). Ten patients required surgery. Median (standard deviation [S.D.]) probability of survival was 0.996 (0.052) and median revised trauma score (RTS) (S.D.) was 7.841 (0.624). There were no fatalities. Potentially serious horse-related injuries presented once every 6 weeks. CONCLUSION: Most injuries are minor and affect the trunk but occur out of hours. Helmets, face shields and body protectors should be worn when riding or handling horses.     

Seroepidemiological study in a Puumala virus outbreak area in South-East Germany

Puumala virus (PUUV) is the cause of the majority of haemorrhagic fever with renal syndrome cases in Germany. In 2004, a nephropathia epidemica outbreak was recorded in Lower Bavaria, South-East Germany. For a seroepidemiological study in this region including the resident population at four locations (n = 178) and soldiers from one location (n = 208) indirect immunoglobulin M (IgM) and immunoglobulin G (IgG) enzyme-linked immunosorbent assays (ELISAs) and immunoblot tests based on a yeast-expressed PUUV nucleocapsid protein were established. The validation using human serum panels originating from Germany revealed a diagnostic sensitivity and specificity of 98/100% for the IgM ELISA, 99/99% for the IgG ELISA, 99/100% for the IgM immunoblot test and 100/96% for the IgG immunoblot test. Using the novel IgG assays as well as a commercial IgG ELISA and an immunofluorescence assay for the resident population an average prevalence of 6.7% (12 of 178) with a range of 0% (0 of 21) to 11.9% (7 of 59) was observed. Positive serological results were equally distributed between males and females with an average age of 63 for males and 52 for females. The seroprevalence in the soldier group was found to be about 1% with one positive male of 203 (age 46 years) and one positive female of five (age 47 years). In conclusion, the PUUV seroprevalence in the residents of the outbreak region in Lower Bavaria was found to be up to fivefold higher than the average hantavirus seroprevalence of the German population.     

Recombinant-antibody-mediated resistance against <Emphasis Type="Italic">Tomato yellow leaf curl virus</Emphasis> in <Emphasis Type="Italic">Nicotiana benthamiana</Emphasis>

Tomato yellow leaf curl virus (TYLCV) is a geminivirus species whose members cause severe crop losses in the tropics and subtropics. We report the expression of a single-chain variable fragment (scFv) antibody that protected Nicotiana benthamiana plants from a prevalent Iranian isolate of the virus (TYLCV-Ir). Two recombinant antibodies (scFv-ScRep1 and scFv-ScRep2) interacting with the multifunctional replication initiator protein (Rep) were obtained from phage display libraries and expressed in plants, both as stand-alone proteins and as N-terminal GFP fusions. Initial results indicated that both scFvs and both fusions accumulated to a detectable level in the cytosol and nucleus of plant cells. Transgenic plants challenged with TYLCV-Ir showed that the scFv-ScRep1, but more so the fusion proteins, were able to suppress TYLCV-Ir replication. These results show that expression of a scFv-ScRep1-GFP fusion protein can attenuate viral DNA replication and prevent the development of disease symptoms. The present article describes the first successful application of a recombinant antibody-mediated resistance approach against a plant DNA virus.     

ARC is a critical cardiomyocyte survival switch in doxorubicin cardiotoxicity

Despite its complexity of action, doxorubicin (Dox)-induced cardiomyopathy eventually results in loss of cardiac myocytes which further contributes to the development of overt heart failure. In the present study, we examined the relevance of the apoptosis repressor with caspase recruitment domain (ARC) on cardiac myocyte survival and its underlying mechanisms in a model of Dox-induced cardiotoxicity. Exposure of neonatal rat ventricular cardiomyocytes with Dox resulted in a downregulation of ARC mRNA and protein levels that occurred in a pre-translational and post-translational manner and led to a significant induction of apoptosis. Proteasomal inhibitors partially rescued both Dox-induced downregulation of ARC protein and induction of apoptosis. Knockdown of endogenous ARC sensitised cardiomyocytes to undergo apoptosis upon treatment with Dox. In contrast, enforced expression of ARC by adenoviral-mediated gene transfer dramatically increased the resistance of cardiomyocytes to undergo apoptotic cell death following Dox administration. In response to Dox, Bax translocated from cytosol to mitochondria where it resulted in dissipation of the mitochondrial membrane potential, cytochrome c release and activation of caspases -3 and -9. ARC prevented Bax translocation to the mitochondrium and thereby blocked the activation of the mitochondrial apoptotic death pathway in a t-Bid and caspase-8-independent manner. In this study, we provide evidence for the protective role of anti-apoptotic ARC in Dox-induced cardiotoxicity, which makes this molecule an interesting target for future therapies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Junfeng An and Peifeng Li have contributed equally.