Advanced single-slice rebinning for tilted spiral cone-beam CT.

Future medical CT scanners and today's micro CT scanners demand cone-beam reconstruction algorithms that are capable of reconstructing data acquired from a tilted spiral trajectory where the vector of rotation is not necessarily parallel to the vector of table increment. For the medical CT scanner this case of nonparallel object motion is met for nonzero gantry tilt: the table moves into a direction that is not perpendicular to the plane of rotation. Since this is not a special application of medical CT but rather a daily routine in head exams, there is a strong need for corresponding reconstruction algorithms. In contrast to medical CT, where the special case of nonperpendicular motion is used on purpose, micro CT scanners cannot avoid aberrations of the rotational axis and the table increment vector due to alignment problems. Especially for those micro CT scanners that have the lifting stage mounted on the rotation table (in contrast to setups where the lifting stage holds the rotation table), this kind of misalignment is equivalent to a gantry tilt. We therefore generalize the advanced single-slice rebinning algorithm (ASSR), which is considered a very promising approach for medical cone-beam reconstruction due to its high image quality and its high reconstruction speed [Med. Phys. 27, 754-772 (2000)], to the case of tilted gantries. We evaluate this extended ASSR approach (which we will denote as ASSR+, for convenience) in comparison to the original ASSR algorithm using simulated phantom data for reconstruction. For the case of nonparallel object motion ASSR+ shows significant improvements over ASSR, however, its computational complexity is slightly increased due to the broken symmetry of the spiral trajectory.     

PATIENT ACCIDENTS IN HOSPITAL: INCIDENCE,DOCUMENTATION AND SIGNIFICANCE

SUMMARY Many previous studies of reported patient accidents in hospital used the accident report forms as the only data source, without questioning their reliability and despite 80% of the accidents being unwitnessed. This paper reports on three studies using data from patient interviews, staff questionnaires, medical and nursing notes and the accident report forms. The studies confirm that falls amongst elderly patients are the most common type of patient accident. However, patients' and staff's versions of the event often differed widely. Accident reports are stated to be required for legal purposes, but they were often incomplete and unreliable. Patient accidents and safety are too important to remain marginalised to mere compliance with out-of-date regulations. A new, ‘slim-line‘, more accurate but less time-consuming patient accident reporting system should be developed, for which improvement in patient safety is the main aim and legal considerations the secondary aim.     

癫痫患者全夜自然睡眠结构的研究

目的　观察癫痫患者发作间期全夜自然睡眠结构特点 ,并评价其与正常对照组睡眠结构的差异 ;评价发作类型、用药情况及是否记录到发作间电发放对睡眠结构的影响。方法　对 2 0名癫痫患者及 11名对照进行全夜自然睡眠多导监测 ,并结合患者的发作类型、是否记录到发作间电发放 (IIDs)及服用 AEDs的情况进行分组统计分析 ,评价各组患者与正常对照间各睡眠参数的差异。结果　癫痫患者组 ,记录到 IIDs组 ,及该组患者中部分性发作者和未服 AEDs者均较正常对照 TRT、RL 显著延长 (P<0 .0 5)。记录到 IIDs的患者睡眠效率显著下降 (P≤0 .0 5) ,其中部分性发作者入睡后觉醒次数较全身性发作者显著增多 (P<0 .0 5)。部分性发作者较全身性发作者NREM睡眠期转换次数有增高的趋势。不同用药癫痫患者睡眠脑电图较正常对照组睡眠破碎性增加。结论　癫痫患者与正常对照比较 RL延长 ;睡眠破碎性增加 ;记录到 IIDs的患者睡眠效率降低 ;部分性发作患者较全身性发作患者有 NREM期转换次数频繁的趋势 ;记录到 IIDs患者中服用 AEDs的情况对其睡眠结构无显著影响。     

Castleman's disease with isolated extensive cervical involvement

Castleman's disease is a lymphoproliferative disorder of uncertain cause characterized by a distinctive pattern of hypervascular lymphoid hyperplasia. Computed tomography and MRI can be used to define the extent of disease. The latter may be used to detect curvilinear hypointensities within the abnormal node. Symmetrical involvement of nasopharyngeal and parapharyngeal regions in our case without disease elsewhere is considered to be an unusual presentation.     

Persistent Organochlorine Contaminant Residues in Tissues of Hedgehogs from Turkey

The residues of persistent organochlorinated pollutants (POPs), namely polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) (HCHs, CHLs, HCCPs, DDTs, and dicofol congeners) were investigated in the hair and muscle of road-killed Erinaceus roumanicus and E. concolor in Turkey. Mean residue levels were as follows: in hair, PCBs?=?7.43?±?4.88 ng/g and OCPs?=?9.21?±?1.27 ng/g; in muscle, PCBs?=?30.73?±?2.51 ng/g and OCPs?=?145.04?±?16.59 ng/g. There was no significant difference between species and sex, while there was significant difference between habitats and regions in terms of either total PCB and OCP levels, or POP levels (p?<?0.05). Age was a determinative factor for the bio-accumulation of POPs. The contaminant levels were high in the species, sample areas, and habitats. The data also showed that tissues of hedgehogs are suitable for monitoring and evaluating the bioaccumulation of POP levels in Turkey.     

Cone-beam computed tomography evaluation of palatogingival grooves: a retrospective study with literature review

Objectives

The purpose of the present study was to radiographically evaluate the prevalence and characteristics of palatogingival grooves (PGs) in maxillary anterior teeth on cone-beam computed tomography (CBCT) to better understand the nature of these defects.

Methods

The CBCT examinations of 993 teeth (330 canines, 315 lateral incisors, 348 central incisors) in 191 patients (87 males, 104 females; age range 16–80 years) were evaluated retrospectively. The diagnosis and radiographic condition of PGs were obtained by consensus among all observers. Verification of PGs was achieved from the patients’ clinical records, which were stored in a database after their clinical evaluation. Differences in age, sex, occurrence, and location were evaluated by the Chi-square test. The level of significance was set at p < 0.05.

Results

Among the 993 teeth examined, nine PGs were observed in seven lateral incisors and two central incisors in eight patients (four males and four females). There was one bilateral case in the lateral incisors. The frequencies of PG occurrence and affected patients were 0.90 and 4.18%, respectively, without significance for sex and location (p > 0.05).

Conclusions

PGs were a relatively infrequent anomaly of teeth in this population, but when present, clinicians should understand the clinical features of these root variations.

     

The Forgotten Variable of Shear Stress in Mitral Annular Calcification: Whole Blood Viscosity

Objective

The aim of this research was to assess the relationship between mitral annular calcification (MAC) and whole blood viscosity (WBV).

Subjects and Methods

A total of 184 patients with MAC and 133 patients without MAC were enrolled in the study. The WBV was calculated with a confirmed formulation using the hematocrit and total plasma protein at a low shear rate (LSR) and high shear rate (HSR). Early diastolic mitral annular velocity (Ea) and late diastolic mitral annular velocity (Aa) were measured using pulse Doppler tissue echocardiography. Pearson''s correlation analysis was performed to assess the relationship between WBV and mitral annular motion velocities. The effects of different variables on the occurrence of MAC were assessed in univariate and multivariate logistic regression analysis.

Results

In patients with MAC, WBV values were significantly higher at HSR (18.04 ± 0.84 vs. 17.25 ± 0.96 208 s^-1, p < 0.001) and at LSR (78.0 ± 14.2 vs. 61.9 ± 17.1 0.5 s^-1, p < 0.001). The WBV at HSR and LSR were significantly correlated with Ea (r = −0.477, p < 0.001; r = −0.385, p < 0.001, respectively) and Aa (r = −0.544, p < 0.001; r = −0.323, p < 0.001, respectively). Multivariate analysis showed that WBV of both shear rates was an independent predictor of MAC. Using the ROC curve, a cut-off value of 70.1 for WBV at LSR had a sensitivity of 83.7% and a specificity of 73.7% (AUC 0.785, p < 0.001) and a WBV cut-off value of 17.5 at HSR had a sensitivity of 79.6% and a specificity of 71.4% (AUC 0.761, p < 0.001) for the prediction of MAC.

Conclusion

Patients with MAC had significantly higher WBV, which independently predicted the presence of MAC. WBV had an inverse correlation with mitral annular motion velocities, indicating that a higher WBV may lead to greater limitation in annular motion and, thus, more calcification.Key Words: Mitral valve calcification, Shear stress, Blood viscosity     

High-resolution spiral CT of the breast at very low dose: concept and feasibility considerations

Objective  

Mammography, today’s standard imaging approach, has deficits with respect to the superimposition of anatomical structures. Dedicated CT of the breast so far indicated that it can provide superior soft-tissue imaging, but that it still has significant limitations with respect to spatial resolution and dose. We have assessed novel dedicated breast CT technology.