Catheter tracking for MR fluoroscopy: design of a transmit/receive coil for use with a nasogastric tube

A coil tuned to 21.3 MHz was incorporated into a nasogastric tube and used as a marker of tube position during magnetic resonance (MR) imaging in a 0.5-T scanner. Catheter tracking was investigated with the coil used in both transmit/receive and in receive-only modes. Data acquired from this coil were overlaid on images obtained using the body coil of the scanner. Visualization of the full length of the catheter with local high signal at the tip was achieved with a temporal resolution of approximately 1 second. J. Magn. Reson. Imaging 2001;13:127-130.     

The role of acid in the pathogenesis of indomethacin-induced gastric antral ulcers in the rat.

BACKGROUND: The role of acid in the pathogenesis of indomethacin- induced ulcers of the rat gastric antrum was studied by comparing the effects of pretreating animals with both long-acting (loxtidine, AH22216) and short-acting (ranitidine and cimetidine) inhibitors of acid secretion. RESULTS: Ranitidine and cimetidine were much weaker at inhibiting antral damage when compared to their reported potencies as antisecretory agents. In marked contrast, loxtidine and AH22216 inhibited indomethacin-induced antral ulcers at doses similar to their reported potencies as inhibitors of acid secretion. Histological analysis at doses causing near maximal inhibition of macroscopic damage revealed an almost complete absence of ulcers but a large and significant increase in mucosal damage due to superficial erosions. Hourly dosing with hydrochloric acid reversed the protective effect of ranitidine, cimetidine and loxtidine on macroscopic damage and, histologically, this was associated with the widespread appearance of antral ulcers and a reduction in the proportion of mucosal damage caused by superficial erosions. CONCLUSIONS: The results of this study suggest that the pathogenesis of nonsteroidal anti-inflammatory drug (NSAID)-induced antral ulcers involves at least two stages: (1) an initial acid-independent formation of mucosal erosions followed by (2) an acid-dependent conversion of erosions to frank ulcers. Clinically, drugs that suppress acid completely for long periods may be very effective in preventing NSAID-induced gastric antral ulcers.     

Borderline tumors of the ovary: CT and MRI features and tumor markers in differentiation from stage I disease

OBJECTIVE: We sought to describe MDCT and MRI features and tumor marker levels that differentiate borderline ovarian tumors from stage I ovarian tumors. CONCLUSION: Borderline ovarian tumors are complex masses with imaging features similar to stage I tumors. The thickness of septations and the size of solid components are significantly larger in stage I tumors, and these features may be helpful for predicting likelihood of invasive tumors. However, neither feature allows confident differentiation of borderline tumors from stage I disease.     

Esophageal cancer staging with endoscopic MR imaging: pilot study

The authors defined esophageal anatomy and evaluated esophageal cancer staging in a pilot group by comparing endoscopic magnetic resonance (MR) imaging results with pathologic and endoscopic ultrasonographic (US) results when available. A porcine esophagus, one volunteer, and 23 patients suspected of having esophageal cancer were imaged at 0.5 T. MR imaging was successful in 21 patients. Eight of these patients underwent esophagectomy (one after chemotherapy, which invalidated comparison with MR imaging; another did not undergo lymphadenectomy) and one underwent laparoscopy and nodal staging only; eight underwent US. When verified with pathologic staging, endoscopic MR imaging was accurate in six of seven patients (T stage) and five of six patients (N stage; nodal areas too obscured by artifact for comparison in one case). MR imaging and US results concurred in seven of eight (T stage) and five of eight (N stage) patients. No complications were observed. Endoscopic MR imaging is safe and probably comparable to endoscopic US, but with a tendency to overstage the disease.     

Validation and reproducibility of computerised cell-viability analysis of tissue slices

Background

The identification of live cells using membrane integrity dyes has become a frequently used technique, especially with articular cartilage and chondrocytes in situ where tissue slices are used to assess cell recovery as a function of location. The development of a reproducible computerised method of cell evaluation would eliminate many variables associated with manual counting and significantly reduce the amount of time required to evaluate experimental results.

Methods

To validate a custom computerised counting program, intra-person and inter-person cell counts of nine human evaluators (three groups – unskilled, novice, and experienced) were compared with repeated pixel counts of the custom program on 15 digitised images (in triplicate) of chondrocytes in situ stained with fluorescent dyes.

Results

Results indicated increased reproducibility with increased experience within evaluators [Intraclass Correlation Coefficient (ICC) range = 0.67 (unskilled) to 0.99 (experienced)] and between evaluators [ICC = 0.47 (unskilled), 0.85 (novice), 0.93 (experienced)]. The computer program had perfect reproducibility (ICC = 1.0). There was a significant relationship between the average of the experienced evaluators results and the custom program results (ICC = 0.77).

Conclusions

This study demonstrated that increased experience in cell counting resulted in increased reproducibility both within and between human evaluators but confirmed that the computer program was the most reproducible. There was a good correlation between the intact cell recovery determined by the computer program and the experienced human evaluators. The results of this study showed that the computer counting program was a reproducible tool to evaluate intact cell recovery after use of membrane integrity dyes on chondrocytes in situ. This and the significant decrease in the time used to count the cells by the computer program advocate its use in future studies because it has significant advantages.

     

QUADAS评价:一种用于诊断性研究的质量评价工具(修订版)

背景 QUADAS是一种新近发展起来的诊断性研究的质量评价工具。虽然已有系统评价采用了QUADAS,但尚未得以正式确证。本研究的目的是评价QUADAS的有效性和实用性。方法3位评价者采用QUADAS独立评价30项研究的质量。比较每位评价者的评分与最终结论之间的意见一致度。这主要是通过比较所有QUADAS条目的总分和每个单项的得分来实现的。20位曾在其系统评价中使用过QUADAS的评价者就其使用经验完成一份简短的问卷。结果就所有条目而言,每位评价者的评分与最终结论之间的意见一致度分别达到了91%、90%和85%。就单项QUADAS条目而言,一致度在50%至100%之间,中位值是90%。与难以解释的试验结果和退出病例相关的条目,评分结果差异最大。有关QUADAS内容的反馈意见普遍较好,仅少数评价者提出了有关QUADAS涵盖面、使用便利性、评分说明的清晰度及有效性方面的问题。结论QUADAS内容本身无需作大的修改。评价过程的主要困难出现在难以解释的试验结果和退出病例这2个条目的评分上。对这些条目的评分指南提出了修改意见。评价者必需根据其系统评价制定相应的评分指南,并确保所有评价者都清楚如何评分。评价者还应考虑是否所有的QUADAS条目都与其系统评价相关,以及其他质量条目是否应作为其系统评价的评价部分。