The clinical utility of reduced-distortion readout-segmented echo-planar imaging in the head and neck region: initial experience

Objectives

To evaluate whether readout-segmented echo-planar imaging (RS-EPI) diffusion weighted image (DWI) can diminish image distortion in the head and neck area, compared with single-shot (SS)-EPI DWI.

Methods

We conducted phantom and patient studies using 3 T magnetic resonance imaging (MRI) with a 16-channel coil. For the phantom study, we evaluated distortion and signal homogeneity in gel phantoms. For the patient study, 29 consecutive patients with clinically suspicious parotid lesions were prospectively enrolled. RS-EPI and SS-EPI DWI were evaluated by two independent readers for identification of organ/lesion and distortion, using semiquantitative scales and quantitative scores. Apparent diffusion coefficient (ADC) values and contrast-noise ratios of parotid tumours (if present; n?=?15) were also compared.

Results

The phantom experiments showed that RS-EPI provided less distorted and more homogeneous ADC maps than SS-EPI. In the patient study, RS-EPI was found to provide significantly less distortion in almost all organs/lesions (p?Conclusions The distortion in DWI was significantly reduced with RS-EPI in both phantom and patient studies. The RS-EPI technique provided more homogenous images than SS-EPI, and can potentially offer higher image quality in the head and neck area.

Key Points

? The distortion in DWI is significantly reduced with RS-EPI compared with SS-EPI. ? Structures in the head and neck were identified more clearly using RS-EPI. ? No significant difference in ADC values was found between the techniques.     

Objective radiologic analysis of ground-glass opacity aimed at curative limited resection for small peripheral non-small cell lung cancer

OBJECTIVE: The aim of this study was to evaluate the efficacy of the objective radiologic analysis of high-resolution computed tomographic images of small peripheral non-small cell lung cancer and to select the candidates for curative limited resection. METHODS: High-resolution computed tomographic images of 146 surgically resected T1 N0 M0 peripheral non-small cell lung cancers were analyzed by using National Institutes of Health image software and classified on the basis of the percentage of ground-glass opacity within the tumor. RESULTS: Eighty-seven percent of tumors with ground-glass opacity ratios of 90% to 100% (type I) were diagnosed as noninvasive bronchioloalveolar carcinoma, whereas 55.6% of tumors with ground-glass opacity ratios of 50% to 89% (type II) consisted of adenocarcinoma. Tumors with ground-glass opacity ratios of 50% or more (type I/II) had no nodal involvement, whereas nodal metastases were identified in 20.0% of tumors with ground-glass opacity ratios of 10% to 49% (type III) and 24.4% of tumors with ground-glass opacity ratios of less than 10% (type IV). No tumors with ground-glass opacity ratios of 50% or more showed vessel infiltration, except for one lesion with a ground-glass opacity ratio of 50%. The 3-year disease-free survival was 97.7% for type I/II, 86.1% for type III, and 78.5% for type IV tumors. CONCLUSIONS: The objective quantitative radiologic analysis with National Institutes of Health image software exhibited a good correlation with the histologic classification, pathologic invasiveness, and postoperative outcome of small peripheral lung cancer. Patients with tumors that have ground-glass opacity ratios of greater than 50% are considered to be possible candidates for limited pulmonary resection.     

Impaired cutaneous wound healing in mice lacking tetranectin

Tetranectin was originally purified from human serum on the basis of plasminogen kringle 4-binding properties. Tetranectin enhances plasminogen activation by a tissue-type plasminogen activator so that it has been suggested to play a role in tissue remodeling. We have generated mice with a targeted disruption of the tetranectin gene to elucidate the biological function of tetranectin. In this study, we showed that wound healing was markedly delayed in tetranectin-null mice compared with wild-type mice. A single full-thickness incision was made in the dorsal skin. By 14 days after the incision, the wounds fully healed in all wild-type mice based on the macroscopic closure; in contrast, the progress of wound healing in the tetranectin null mice appeared to be impaired. In histological analysis, wounds of wild-type mice showed complete reepithelialization and healed by 14 days after the incision. However, those of tetranectin-null mice never showed complete reepithelialization at 14 days. At 21 days after the injury, the wound healed and was covered with an epidermis. These results supported the fact that tetranectin may play a role in the wound healing process.     

Evaluation of video-assisted thoracoscopic surgery lobectomy requiring emergency conversion to thoracotomy

Objective: Video-assisted thoracoscopic surgery (VATS) lobectomy has been employed for the treatment of lung cancer. Many investigators have reported that the outcomes of VATS lobectomy for lung cancer are comparable to those of thoracotomy; however, several controversial issues remain. One of the critical concerns is the safety. VATS lobectomy often requires an emergency conversion to thoracotomy, for example, in the event of massive bleeding. In this study, cases in which VATS lobectomy for lung cancer was converted to thoracotomy intra-operatively (converted VATS lobectomy) were identified. The safety of the converted VATS lobectomy was evaluated. Methods: Between 2003 and 2007, VATS lobectomy was converted to thoracotomy in 24 out of 492 cases. Information regarding the patients’ characteristics, reasons for the conversion and perioperative complications as well as the recurrence and survival data were carefully reviewed. The reasons for the conversion were classified into two groups: (1) problems related to the VATS procedure (VATS-related problems) and (2) problems not related to the VATS procedure (non-VATS-related problems). Results: Of the 24 converted cases, 19 (79%) had a history of smoking. Nine patients (38%) had a history of lung disease. Left upper lobectomy was the most frequently associated with conversion (11/24, 46%), followed by right lower lobectomy and right upper lobectomy. The most frequent reasons for the conversion were hilar lymphadenopathy and bleeding (seven patients each), followed by fused fissure. Eight of the conversions were considered to be attributable to VATS-related problems. Perioperative complications were observed in four patients, consisting of prolonged air leak in three patients and transient recurrent laryngeal nerve palsy in one patient. However, there were no life-threatening complications. The median follow-up period was 26 months. Recurrence occurred in two patients: pleural dissemination in one and bone metastasis in the other. Two deaths were observed during the follow-up period: one related to lung cancer and another related to other type of cancer. Conclusions: The safety of the conversion was acceptable. Our findings suggest that VATS lobectomy for lung cancer is feasible from the viewpoint of safety, even after taking into account the potential need for conversion to thoracotomy in some patients.     

Basolateral Na+/H+ exchange maintains potassium secretion during diminished sodium transport in the rabbit cortical collecting duct

Stimulation of the basolateral Na(+)/K(+)-ATPase in the isolated perfused rabbit cortical collecting duct by raising either bath potassium or lumen sodium increases potassium secretion, sodium absorption and their apical conductances. Here we determined the effect of stimulating Na(+)/K(+)-ATPase on potassium secretion without luminal sodium transport. Acutely raising bath potassium concentrations from 2.5 to 8.5 mM, without luminal sodium, depolarized the basolateral membrane and transepithelial voltages while increasing the transepithelial, basolateral and apical membrane conductances of principal cells. Fractional apical membrane resistance and cell pH were elevated. Net potassium secretion was maintained albeit diminished and was still enhanced by raising bath potassium, but was reduced by basolateral ethylisopropylamiloride, an inhibitor of Na(+)/H(+) exchange. Luminal iberitoxin, a specific inhibitor of the calcium-activated big-conductance potassium (BK) channel, impaired potassium secretion both in the presence and absence of luminal sodium. In contrast, iberitoxin did not affect luminal sodium transport. We conclude that basolateral Na(+)/H(+) exchange in the cortical collecting duct plays an important role in maintaining potassium secretion during compromised sodium supplies and that BK channels contribute to potassium secretion.     

Laparoscopic subtotal cholecystectomy for severe cholecystitis

Purpose

To evaluate the efficacy and outcome of laparoscopic subtotal cholecystectomy (LSC) for patients with severe cholecystitis.

Methods

Between April 1992 and May 2008, 1226 patients underwent laparoscopic cholecystectomy (LC). From 2000 onward 60 patients with severe cholecystitis underwent LSC. The outcomes of LC were compared between patients who underwent the procedure between 1992 and 1999 (group A; n = 643) and those who underwent the procedure between 2000 and 2008 after the introduction of LSC (group B; n = 583), respectively. In Group B, operative outcomes were also compared between the LC and LSC groups.

Results

The incidence of bile duct injury (1.6% vs 0.3%, P = 0.040) and conversion to open cholecystectomy (2.2% vs 0.3%, P = 0.046) was significantly lower in group B. The mean operative time was significantly longer (119.6 min vs 71.0 min., P < 0.001), and the mean blood loss was significantly higher (53.4 ml vs 12.9 ml, P < 0.001) in the LSC group. No significant differences were observed between LC and LSC in the incidence of postoperative morbidities or postoperative hospital stay. No patient had remnant gallstones or gallbladder cancers after a median follow-up of 42 months.

Conclusions

Laparoscopic subtotal cholecystectomy is safe and effective for preventing bile duct injuries and lowering the conversion rate in patients with technically difficult severe cholecystitis.     

The frontal cortex is activated during learning of endoscopic procedures

Background

To date, several training and evaluation systems for endoscopic surgery have been developed, such as virtual-reality simulators and box trainers. However, despite current advances in these objective assessments, no functional brain studies during learning of endoscopic surgical skills have been carried out. In the present study, we investigated cortical activation using near-infrared spectroscopy (NIRS) during endoscopic surgical tasks.

Study design

A total of 21 right-handed subjects, comprising 4 surgical experts, 4 trainees, and 13 novices, participated in the study. Suturing and knot-tying tasks were performed in a box trainer. Cortical activation was assessed in all subjects by task-related changes in hemoglobin (Hb) oxygenation using NIRS.

Results

In surgical experts and novices with no experience of endoscopic surgical training, we found no changes in oxy-Hb, deoxy-Hb or total-Hb levels in any of the frontal channels. In surgical trainees and one novice with experience of endoscopic surgical training, we found significant increases in oxy-Hb and total-Hb levels in most of the frontal channels. There were significant differences in oxy-Hb and total-Hb levels in CH-19 between surgical experts and trainees (p = 0.02 for both), and between surgical trainees and novices with no experience of endoscopic surgical training (p = 0.008 for both). Furthermore, additional training increased oxy-Hb levels in the frontal cortex of novices with no experience of endoscopic surgical training but had no such effect on surgical experts.

Conclusions

The present data suggest that NIRS is a feasible tool for assessing brain activation during endoscopic surgical tasks, and may have a large impact on the future development of teaching, training, and assessment methods for endoscopic surgical skills.     

Lethal and Mutagenic Effects of 252Cf Radiation in Cultured Human Cells

Summary

HeLa MR cells were exposed to radiation emitted from a man-made spontaneously fissioning isotope, californium-252. The neutron to gamma-ray ratio in the radiation dose was measured to be 2·0. The extrapolation number of the dose-survival curve was 1·3 and the Do was 200 cGy. A dose-dependent increase in mutation to 6-TG^r (6-thioguanine resistant) was observed. The relative biological effectiveness (r.b.e.) for cell killing of the neutrons from ²⁵²Cf, calculated relative to high-dose-rate X-rays, was 2·6 at 50 per cent survival. The r.b.e. for mutation induction was 2·7 at a mutation frequency of 5 × 10^?5 per surviving cell.     

Subtraction CT angiography with controlled-orbit helical scanning for detection of intracranial aneurysms.

PURPOSEOur goal was to evaluate the utility of subtraction three-dimensional CT angiography for the detection of intracranial aneurysms.METHODSThirty-six patients with intracranial aneurysms were examined using newly devised controlled-orbit helical scanning and conventional angiography. Three-dimensional CT angiograms and subtraction 3-D CT angiograms were compared with conventional angiograms for their characterization of intracranial aneurysms.RESULTSFifty aneurysms were depicted on conventional angiograms, of which 48 (96%) were seen on the 3-D CT angiograms. Three-dimensional CT angiography was superior or equivalent to conventional angiography for depicting the shape, direction, and location of 33 (66%) of 50 aneurysms; however, it was often less useful than conventional angiography in delineating intracranial aneurysms adjacent to bone. Subtraction 3-D CT angiograms were obtained in 32 patients with a total of 46 aneurysms (in four cases, aneurysms were not depicted owing to excessive motion artifacts), and were superior or equivalent to conventional angiograms in all 46 cases.CONCLUSIONSSubtraction 3-D CT angiography with the use of controlled-orbit helical scanning is effective in the detection of intracranial aneurysms.     

Sequential changes on23Na MRI after cerebral infarction

²³Na MRI changes from the acute to chronic phase were investigated in seven patients with cerebral in-farcts. They showed no signal increase during the first 13 h after the stroke and revealed a definite signal increase thereafter. This reached a maximum 45–82 h after stroke and became slightly less marked in the subactue and chronic phases, probably as a result of disappearance of cerebral oedema. In the early acute phase of stroke,²³Na MRI appears to fail to demonstrate Na⁺ increases in the ischaemic area, due presumably to the invisibility on MRI of intracellular²³Na in the intact brain. The increase more than 13 h after stroke, during which ischaemic cells are likely to die, is presumably because of increased visibility of intracellular²³Na in the dead cells.²³Na MRI is apparently insensitive to early ischaemic changes, but may be useful for assessing the cell viability in the ischaemic brain.