Non-invasive quantitative pulmonary V/Q imaging using Fourier decomposition MRI at 1.5T

ObjectivesTechniques for quantitative pulmonary perfusion and ventilation using the Fourier Decomposition method were recently demonstrated. We combine these two techniques and show that ventilation-perfusion (V/Q) imaging is possible using only a single MR acquisition of less than thirty seconds.MethodsThe Fourier Decomposition method is used in combination with two quantification techniques, which extract baselines from within the images themselves and thus allows quantification. For the perfusion, a region assumed to consist of 100% blood is utilized, while for the ventilation the zero-frequency component is used. V/Q-imaging is then done by dividing the quantified ventilation map with the quantified perfusion map. The techniques were used on ten healthy volunteers and fifteen patients diagnosed with lung cancer.ResultsA mean V/Q-ratio of 1.15±0.22 was found for the healthy volunteers and a mean V/Q-ratio of 1.93±0.83 for the non-afflicted lung in the patients. Mean V/Q-ratio in the afflicted (tumor-bearing) lung was found to be 1.61±1.06. Functional defects were clearly visible in many of the patient images, but 5 of 15 patient images had to be excluded due to artifacts or low SNR, indicating a lack of robustness.ConclusionNon-invasive, quantitative V/Q-imaging is possible using Fourier Decomposition MRI. The method requires only a single acquisition of less than 30 seconds, but robustness in patients remains an issue.     

Effects of Systemic Administration of Dexmedetomidine on Intraocular Pressure and Ocular Perfusion Pressure during Laparoscopic Surgery in a Steep Trendelenburg Position: Prospective,Randomized, Double-Blinded Study

Increased intraocular pressure (IOP) during surgery is a risk factor for postoperative ophthalmological complications. We assessed the efficacy of systemically infused dexmedetomidine in preventing the increase in IOP caused by a steep Trendelenburg position, and evaluated the influence of underlying hypertension on IOP during surgery. Sixty patients undergoing laparoscopic surgery in a steep Trendelenburg position were included. Patients in the dexmedetomidine group received a 1.0 µg/kg IV loading dose of dexmedetomidine before anesthesia, followed by an infusion of 0.5 µg/kg/hr throughout the operation. Patients in the saline group were infused with the same volume of normal saline. IOP and ocular perfusion pressure (OPP) were measured 16 times pre- and intraoperatively. In the saline group, IOP increased in the steep Trendelenburg position, and was 11.3 mmHg higher at the end of the time at the position compared with the baseline value (before anesthetic induction). This increase in IOP was attenuated in the dexmedetomidine group, for which IOP was only 4.2 mmHg higher (P < 0.001 vs. the saline group). The steep Trendelenburg position was associated with a decrease in OPP; the degree of decrease was comparable for both groups. In intragroup comparisons between patients with underlying hypertension and normotensive patients, the values of IOP at every time point were comparable. Dexmedetomidine infusion attenuated the increase in IOP during laparoscopic surgery in a steep Trendelenburg position, without further decreasing the OPP. Systemic hypertension did not seem to be associated with any additional increase in IOP during surgery. (Registration at the Clinical Research Information Service of Korea National Institute of Health ID: KCT0001482)     

Liver MRI: From basic protocol to advanced techniques

Liver MR is a well-established modality with multiparametric capabilities. However, to take advantage of its full capacity, it is mandatory to master the technique and optimize imaging protocols, apply advanced imaging concepts and understand the use of different contrast media. Physiologic artefacts although inherent to upper abdominal studies can be minimized using triggering techniques and new strategies for motion control. For standardization, the liver MR protocol should include motion-resistant T2-w sequences, in-op phase GRE T1 and T2-w fast spin echo sequences with fat suppression. Diffusion-weighted imaging (DWI) is mandatory, especially for detection of sub-centimetre metastases. Contrast-enhanced MR is the cornerstone of liver MR, especially for lesion characterization. Although extracellular agents are the most extensively used contrast agents, hepatobiliary contrast media can provide an extra-layer of functional diagnostic information adding to the diagnostic value of liver MR. The use of high field strength (3T) increases SNR but is more challenging especially concerning artefact control. Quantitative MR belongs to the new and evolving field of radiomics where the use of emerging biomarkers such as perfusion or DWI can derive new information regarding disease detection, prognostication and evaluation of tumour response. This information can overcome some of the limitations of current tests, especially when using vascular disruptive agents for oncologic treatment assessment. MR is, today, a robust, mature, multiparametric imaging modality where clinical applications have greatly expanded from morphology to advanced imaging. This new concept should be acknowledged by all those involved in producing high quality, high-end liver MR studies.     

Saccharic acid 1.4-lactone protects against CPT-11-induced mucosa damage in rats

Purpose To evaluate the ability of D-saccharic acid 1.4-lactone (SAL), a -glucuronidase inhibitor, to prevent irinotecan hydrochloride (CPT-11) from inducing mucosal damage as a cause of diarrhea in rats.Methods Wistar rats were divided into six groups of three animals each, administered 1.0 ml isotonic solution intraperitoneally once daily for up to three consecutive days, respectively for up to six days. The series were as follows: (1) On days 1–3: saline; (2). On days 1–3: 200 mg CPT-11/m²; (3) On days –3 to –1 relative to the first administration of CPT-11: 10 mg/ml SAL; on days 1–3: 200 mg CPT-11/m²; (4) On days –3 to +3 relative to the first administration of CPT-11: 10 mg/ml SAL, and on days 1–3: additional 200 mg CPT-11/m²; (5) On days 1–3: 200 mg CPT-11/m² (0.5 ml) + 10 mg/0.5 ml SAL; (6) On days –3 to –1 relative to the first administration of CPT-11: 3 mg/ml SAL, and on days 1–3: 200 mg CPT-11/m². Luminal mucosa damage of the small intestine was detected by histology 24 h after the last intraperitoneal application. Peptidase activities of the proximal jejunum were measured by using an in situ perfusion model.Results Following intraperitoneal CPT-11 treatment, using conventional histology of paraffin sections, we observed severe mucosal damage. This was reflected by a decrease of the villi/crypt ratio, an increase of apoptotic cells, as well as an increase of mitotic figures in the crypt region. There was a concomitant increased lymphatic infiltration in mucosa of CPT-11 treated rats. This damage pattern could be clearly reduced by co-treatment with the -glucuronidase inhibitor, SAL, independent of the treatment schedule. In contrast to our expectations based on previous reports, the intraperitoneal application of CPT-11 alone or in combination with SAL did not cause significant differences in luminal enzyme liberation in comparison with controls in the in situ perfusion assay.Conclusions The -glucuronidase inhibitor SAL is able to significantly reduce CPT-11-induced mucosal damage in the small intestine of rats. This observation might soon have a clinical impact for the treatment of patients with CPT-11.     

优化低剂量一站式全脑CT灌注成像联合CTA扫描方案

目的 探讨优化一站式全脑CT灌注成像（CTP）联合CTA扫描方案。方法 对45例受检者行一站式全脑CTP联合CTA,共进行22期相扫描,并采用3种扫描方案,选取第10期相灌注图像重建CTA图像,其中A组为自动管电流调制（ATCM）技术及低噪声指数（噪声指数=2）,B组为管电流325 mA,C组为ATCM及稍低噪声指数（噪声指数=2.5）;3组其余各期相均采用ATCM技术且噪声指数设定为8;3组扫描方案的管电压均为100 kV。记录辐射剂量相关参数,比较CTA、CTP图像的噪声（SD）、SNR、CNR及不同部位脑实质各灌注参数值及CTA、CTP图像的主观评分。结果 3组有效剂量（ED）差异有统计学意义（P<0.05）,其中A组ED明显高于B、C组（P=0.043、0.001）;3组CTA图像噪声、SNR、CNR及主观评分差异无统计学意义（P=0.218、0.545、0.575、0.900）,CTP图像相应部位图像噪声、SNR、各灌注参数值及主观评分差异均无统计学意义（P均>0.05）。结论 采用ATCM技术一站式全脑CTP联合CTA检查可通过适当增加噪声指数减低患者辐射剂量。     

Five-year mortality in patients with diabetic foot ulcer during 2009–2010 was lower than expected

AimMortality rates are decreasing in patients with diabetes. However, as this observation also concerns patients with diabetic foot ulcer (DFU), additional data are needed. For this reason, our study evaluated the 5-year mortality rate in patients with DFU during 2009–2010 and identified risk factors associated with mortality.MethodsConsecutive patients who attended a clinic for new DFU during 2009–2010 were followed until healing and at 1 year. Data on mortality were collected at year 5. Multivariate Cox proportional-hazards model was used to identify mortality risk factors.ResultsA total of 347 patients were included: mean age was 65 ± 12 years, diabetes duration was 16 [10; 27] years; 13% were on dialysis; and 7% had an organ transplant. At 5 years, 49 patients (14%) were considered lost to follow-up. Total mortality rate at 5 years was 35%, and 16% in patients with neuropathy. On multivariate analyses, mortality was positively associated with: age [hazard ratio (HR): 1.05 (1.03–1.07), P < 0.0001]; duration of diabetes [HR: 1.02 (1.001–1.03], P = 0.03]; PEDIS perfusion grade 2 vs. 1 [HR: 2.35 (1.28–4.29), P = 0.006)]; PEDIS perfusion grade 3 vs. 1 [HR: 3.14 (1.58–6.24), P = 0.001); and ulcer duration at year 1 [HR 2.09 (1.35–3.22), P = 0.0009].ConclusionMortality rates were not as high as expected despite the large number of comorbidities, suggesting that progress has been made in the health management of these patients. In particular, patients with neuropathic foot ulcer had a survival rate of 84% at 5 years.     

Dipeptidyl peptidase IV in mammalian lungs

Endothelial cells of the pulmonary circulation are equipped with an ectoenzyme protease system on their luminal surface. The membrane-bound proteases act on the circulating polypeptides and cleave certain peptide bonds in their structure, thus modifying their biological properties. We studied the enzyme dipeptidyl peptidase IV (DP-IV) in mammalian lungs in order to elucidate its contribution to the aforementioned proteolytic processing. We have found that lungs of mammalian species posses DP-IV with different levels of specific activity. In rat lungs the specific activity of DP-IV progressively increased during development between the 18th fetal and the 70th postnatal days. Human embryonal and fetal lungs had significantly higher specific activity of DP-IV compared with the lungs of adult individuals. The enzyme in lungs was mainly membrane bound and was solubilized by some detergents, but not with papain and trypsin. The Triton X-100-solubilized DP-IV from rat lung lysosomal-microsomal membranes migrated during electrophoresis on continuous 4–30% gradient polyacrylamide gel at native apparent M_r values of 260 000 and 490 000. Using a histochemical technique we found the enzyme activity of DP-IV in the capillary bed of the lung alveolar septa only. Four aminoacyl-L-proline-4-nitroanilide substrates for DP-IV were cleaved rapidly during one passage through isolated perfused blood-free rat lungs. The perfusion profiles of cleavage of these substrates were largely coincident with that of Blue Dextran 2 000, a compound, which is unlikely to leave the intravascular space. Taken together, the data suggest that DP-IV operates in vivo as a membrane-bound ectoenzyme on the luminal surface of pulmonary endothelial cells and that it may cleave certain circulating polypeptides.     

Validation of histologic bone analysis following Microfil vessel perfusion

Abstract

The ability to examine bone vascularity using micro-computed tomography following vessel perfusion with Microfil^® and to subsequently perform histologic bone analysis in the same specimen would provide an efficient method by which the vascular and cellular environment of bone can be examined simultaneously. The purpose of this report is to determine if the administration of Microfil precludes accurate histologic assessment of bone quality via osteocyte count and empty lacunae count. Sprague–Dawley rats (n?=?6) underwent perfusion with Microfil. Left hemi-mandibles were harvested, decalcified, and underwent vascular analysis via micro-computed tomography prior to sectioning and staining with Gomori’s trichrome. Quantitative histomorphometric evaluation was performed. Ninety-five percent confidence intervals (CIs) were used to determine statistical differences from an established set of controls (n?=?12). Histologic analyses were successfully performed on specimens that had been perfused. Quantitative measures of bone cellularity of perfused versus control specimens revealed no statistical difference in osteocyte count per high-power field (95·33 versus 94·66; 95% CI: ?7·64 to 6·30) or empty lacunae per high-power field (2·73 versus 1·89; 95% CI: ?1·81 to 0·13). A statistical validation is reported that allows histologic analysis of cell counts in specimens which had been perfused with Microfil.