The role of input imaging combination and ADC threshold on segmentation of acute ischemic stroke lesion using U-Net.

BACKGROUND: To evaluate the effect of the weighting of input imaging combo and ADC threshold on the performance of the U-Net and to find an optimized input imaging combo and ADC threshold in segmenting acute ischemic stroke (AIS) lesion. METHODS: This study retrospectively enrolled a total of 212 patients having AIS. Four combos, including ADC-ADC-ADC (AAA), DWI-ADC-ADC (DAA), DWI-DWI-ADC (DDA), and DWI-DWI-DWI (DDD), were used as input images, respectively. Three ADC thresholds including 0.6, 0.8 and 1.8 × 10-3 mm2/s were applied. Dice similarity coefficient (DSC) was used to evaluate the segmentation performance of U-Nets. Nonparametric Kruskal-Wallis test with Tukey-Kramer post-hoc tests were used for comparison. A p < .05 was considered statistically significant. RESULTS: The DSC significantly varied among different combos of images and different ADC thresholds. Hybrid U-Nets outperformed uniform U-Nets at ADC thresholds of 0.6 × 10-3 mm2/s and 0.8 × 10-3 mm2/s (p < .001). The U-Net with imaging combo of DDD had segmentation performance similar to hybrid U-Nets at an ADC threshold of 1.8 × 10-3 mm2/s (p = .062 to 1). The U-Net using the imaging combo of DAA at the ADC threshold of 0.6 × 10-3 mm2/s achieved the highest DSC in the segmentation of AIS lesion. CONCLUSIONS: The segmentation performance of U-Net for AIS varies among the input imaging combos and ADC thresholds. The U-Net is optimized by choosing the imaging combo of DAA at an ADC threshold of 0.6 × 10-3 mm2/s in segmentating AIS lesion with highest DSC. KEY POINTS: • Segmentation performance of U-Net for AIS differs among input imaging combos. • Segmentation performance of U-Net for AIS differs among ADC thresholds. • U-Net is optimized using DAA with ADC = 0.6 × 10-3 mm2/s.

Cerebellar contributions to tactile perception in people with varying sensorimotor experiences: Examining the sensory acquisition hypothesis.

The sensory acquisition hypothesis states that the sensory demand of a task is the most crucial factor in determining the level of cerebellar activity. The present study was conducted to examine whether the prediction of sensory demand holds when participants have different sensorimotor training experiences. Archery athletes and non-athletic control participants were asked to perform tactile discrimination tasks during fMRI scanning. In archery athletes, a pattern of reduced cerebellar activation accompanying higher sensory cortical activity was observed, whereas in non-athletic control participants the visual network was found to be in concert with extensive cerebellar activation. These findings are in accordance with the prediction that the cerebellum plays a supportive role for the cerebral cortex in sensory data acquisition.

Impact of putamen stroke on task context updating: Evidence from P300 brain waves.

According to the context updating theory, the oddball P300 component indexes brain activities underlying revision of the mental representation induced by incoming stimuli. It involves an attention-driven comparison process that evaluates the representation of the previous event in working memory. Delayed latencies have been reported for various types of stroke such as unilateral thalamic stroke. We investigated memory updating effects in patients with putamen stroke. Two groups of patients with putamen and thalamic stroke were recruited along with two control groups of young and old healthy participants. Auditory and visual P300 were elicited respectively in a two-stimulus oddball paradigm. The auditory P300 peak latencies were significantly longer in patients with a putamen lesion than in the aged and young control groups and the same pattern was found in the thalamus-lesioned patient. The delayed auditory P300 component in both patient groups but neither control group suggests impairment of memory updating in patients with putamen stroke comparable with thalamic stroke. Our study illustrates the important role of subcortical structures subserved in context updating.

Reproducibility of corticospinal diffusion tensor tractography in normal subjects and hemiparetic stroke patients.

PURPOSE: The reproducibility of corticospinal diffusion tensor tractography (DTT) for a guideline is important before longitudinal monitoring of the therapy effects in stroke patients. This study aimed to establish the reproducibility of corticospinal DTT indices in healthy subjects and chronic hemiparetic stroke patients. MATERIALS AND METHODS: Written informed consents were obtained from 10 healthy subjects (mean age 25.8 ± 6.8 years), who underwent two scans in one session plus the third scan one week later, and from 15 patients (mean age 47.5 ± 9.1 years, 6-60 months after the onset of stroke, NIHSS scores between 9 and 20) who were scanned thrice on separate days within one month. Diffusion-tensor imaging was performed at 3T with 25 diffusion directions. Corticospinal tracts were reconstructed using fiber assignment by continuous tracking without and with motion/eddy-current corrections. Intra- and inter-rater as well as intra- and inter-session variations of the DTT derived indices (fiber number, apparent diffusion coefficient (ADC), and fractional anisotropy (FA)) were assessed. RESULTS: Intra-session and inter-session coefficients of variations (CVs) are small for FA (1.13-2.09%) and ADC (0.45-1.64%), but much larger for fiber number (8.05-22.4%). Inter-session CVs in the stroke side of patients (22.4%) are higher than those in the normal sides (18.0%) and in the normal subjects (14.7%). Motion/eddy-current correction improved inter-session reproducibility only for the fiber number of the infarcted corticospinal tract (CV reduced from 22.4% to 14.1%). CONCLUSION: The fiber number derived from corticospinal DTT shows substantially lower precision than ADC and FA, with infarcted tracts showing lower reproducibility than the healthy tissues.

Capability of identifying red nuclei in different pulse sequences of regular 1.5-tesla magnetic resonance images.

OBJECTIVE: To investigate the optimal pulse sequences of commonly used 1.5-tesla MRI for identifying the red nucleus (RN) to aid targeting of the subthalamic nucleus (STN). METHODS: Forty-six healthy adults were enrolled for this prospective study. All subjects underwent MR studies of 5 sequences: diffusion-weighted imaging (DWI), T(1)-weighted fluid-attenuated inversion recovery (T1IR), fast spin echo T(2)-weighted imaging (FSE-T2WI), T(2)-weighted fluid-attenuated inversion recovery (T2FLAIR) and T(2)*-weighted gradient-echo (T2*-GRE) sequences. The clearness of the RN contour was analyzed. RESULTS: Overall, the RN was identified in 98% subjects without gender and age differences. The RN was demarcated on a 5-mm slice relatively better in T2FLAIR (93.5%), followed by FSE-T2WI (78.3%), T2*-GRE (65.2%) and DWI (43.5%) sequences, but was completely invisible on the T1IR image. Generally, the signal intensity in all MR sequences decreased mildly on 2-mm slices with a similar identifying power. The detecting power on 5-mm slices was in favor of T2FLAIR with 94% sensitivity, 10% specificity, and 1.89 odds ratio compared to FSE-T2WI. In addition, the scanning time of T2FLAIR was longer in comparison to the FSE-T2WI study. CONCLUSION: T2FLAIR is an alternative to FSE-T2WI that can readily demarcate the RN to help target the STN.

A comparison of the classic and a modified laryngeal mask airway (OPLAC™) in adult patients.

BACKGROUND: A modified disposable laryngeal mask airway (LMA) (Oro-Pharyngo-Laryngeal Airway Cap, OPLAC™) was developed in our department. In this study, we compared the performance of the LMA Classic™ with that of the OPLAC. METHODS: This was a randomized, single-blinded, crossover study involving 60 paralyzed, anesthetized adult patients. Both devices were inserted into each patient in different sequences after anesthesia had been induced. In 30 patients, the LMA was inserted first and in 30 patients, the OPLAC was inserted first. The success rate, insertion time, fiberoptic view, peak airway pressure, sealing pressure, incidence of gastric insufflations, trace of blood on the device, and incidence of postoperative sore throat were evaluated. RESULTS: The success rate of placement on the first attempt was high for both devices. The insertion time was significantly shorter and better engagement was noted on fiberoptic view with the OPLAC than with the LMA. The sealing pressure was significantly higher and the incidence of gastric insufflations was significantly lower with the OPLAC. The overall incidence of sore throat was 13.33%. CONCLUSIONS: Both devices have comparable airflow resistance and are easy to insert. The OPLAC requires less insertion time, has less variation on insertion time, fits better into the laryngopharynx, is less likely to cause gastric insufflations, and has a higher sealing pressure.

Endoscopic evacuation of hypertensive putaminal hemorrhage guided by the 3D reconstructed CT scan: a preliminary report.

OBJECTIVE: The minimally invasive procedure is the trend in nowadays neurosurgical techniques. We designed a new targeting method using three-dimensional (3D) reconstructed CT images combining neuroendoscope for hypertensive putaminal hemorrhage (HPH). METHODS: Eleven consecutive unconscious patients with a significant volume of HPH were treated with neuroendoscope via a selected frontal or temporal trephination. All the CT images were operated and reconstructed by an independent neuroradiologist for measuring the selected frontal or temporal entry point, depth of penetrating path, and surgical trajectory on the basis of the plane formed by bilateral orbitomeatal lines. The nasion and the external auditory meatus were the reference points for the selected frontal and temporal trephinations respectively. All the surgical trajectories were designed as perpendicular to the underground for minimizing the possibility of human errors after aseptic surgical draping. The intra-operatively sonography was routinely used after trephination for confirmation of the planned surgical path and early detection of possible enlarged hematoma. RESULTS: Ten of the 11 patients regained consciousness postoperatively without complications. All the patients had an accurate trajectory of penetrating path and the average hematoma evacuation rate was 82% (83% for frontal approach and 81% for temporal approach). CONCLUSION: Use of the 3D reconstructed CT imaging technique combining neuroendoscope may add as a minimally invasive, economic, and timesaving way for targeting HPH. It also serves as a reliable and useful alternative for hospitals without stereotactic or navigating modalities. However, further prospective studies were needed to clarify its efficacy and safety compared to conventional surgeries.

Recurrent pain after percutaneous vertebroplasty.

OBJECTIVE: The purposes of this review are to summarize the causes of recurrent pain after percutaneous vertebroplasty and to discuss the incidence, clinical symptoms, risk factors, image findings, treatment and prognosis, and prevention of such pain. CONCLUSION: Percutaneous vertebroplasty is widely used to treat patients with symptomatic osteoporotic compression fractures. Although the procedure relieves the pain of the compression fracture, recurrent back pain after percutaneous vertebroplasty is common.

Transarterial embolization for control of bleeding in patients with head and neck cancer.

OBJECTIVE: This study evaluated the efficacy of transarterial embolization for the treatment of tumor bleeding in neck tumors following radiation or chemotherapy. STUDY DESIGN: We performed a case series with chart review of 25 patients with clinically suspected tumor bleeding that occurred in the period between August 2003 and April 2007. SETTING: All patients were admitted to and accepted treatment at China Medical University Hospital, Taiwan, R.O.C. SUBJECTS AND METHODS: Twenty-five male patients (aged 32 to 88 years) with pathologically verified malignant carcinomas of the neck received radiotherapy (n = 6), radiotherapy and chemotherapy (n = 7), or initial surgery and palliative radiotherapy or chemotherapy (n = 12). Carotid artery angiography was performed to detect tumor bleeding, and affected vessels were embolized using either Gelfoam sponge (or cubes), coils, microcoils, or a combination of these methods. RESULTS: By angiography, patients showed tumor vessels with tumor stain (n = 13), extravasation of the contrast agent (n = 7), stenotic vessels (n = 5), pseudoaneurysm (n = 4), and arteriovenous shunt (n = 1). Transarterial embolization was performed with catheter insertion through the branches of the external carotid artery (n = 18), the external carotid artery (n = 5), or the internal carotid artery (n = 1). All patients showed dramatic clinical improvement following embolization. Patients with tongue cancer had the longest average post-transarterial embolization hospital stay (21 days) and the highest incidence of aspiration pneumonia (3/9). After two months of follow-up, five patients had experienced rebleeding. CONCLUSION: Specific vessel injuries following radiation or chemotherapy require different kinds of endovascular treatment. Patients with tongue cancer should be carefully monitored for aspiration pneumonia.

Transcatheter arterial embolization in the treatment of maxillofacial trauma induced life-threatening hemorrhages.

BACKGROUND: Life-threatening hemorrhages with hemodynamic instability are uncommon in patients with sustained maxillofacial trauma, but when they occur, require immediate surgical intervention if conservative treatment fails. This study assessed the effects of transcatheter arterial embolization (TAE) in the treatment of maxillofacial trauma-induced life-threatening hemorrhages. METHODS: From January 2004 to January 2007, eight ambulatory patients admitted for maxillofacial injuries with life-threatening hemorrhaging and hemodynamic instability (systolic blood pressure < or = 90 mm Hg) caused primarily by intractable oronasal bleeding who subsequently underwent TAE were included in this study. RESULTS: Maxillofacial trauma was caused by motorcycle traffic injuries (6 cases), motor vehicle injury (1 case), and fall injury (1 case). All patients exhibited documented Le Fort III fractures. The average Glasgow Coma Scale score was 4.7. TAE was successfully performed and hemorrhaging arrested in all patients. Three deaths occurred (38%) from severe traumatic brain injury. The other five patients (62%) survived without development of systemic or neurologic complications post-TAE. CONCLUSIONS: Conservative treatment consisting of packing of the nares, compression, and blood transfusion should always precede TAE as the primary protocol. When conservative treatment fails, as shown either by the need for continued blood product replacement exceeding 1,500 mL and a systolic blood pressure < or = 90 mm Hg, TAE intervention should immediately be considered as an alternative recourse before other surgical interventions.

The human promyelocytic leukemia protein is a tumor suppressor for murine skin carcinogenesis.

Expression of the PMLRARalpha fusion dominant-negative oncogene in the epidermis of transgenic mice resulted in spontaneous skin tumors attributed to changes in both the PML and RAR pathways [Hansen et al., Cancer Res 2003; 63:5257-5265]. To determine the contribution of PML to skin tumor susceptibility, transgenic mice were generated on an FVB/N background, that overexpressed the human PML protein in epidermis and hair follicles under the control of the bovine keratin 5 promoter. PML was highly expressed in the epidermis and hair follicles of these mice and was also increased in cultured keratinocytes where it was confined to nuclear bodies. While an overt skin phenotype was not detected in young transgenic mice, expression of keratin 10 (K10) was increased in epidermis and hair follicles and cultured keratinocytes. As mice aged, they exhibited extensive alopecia that was accentuated on the C57BL/6J background. Following skin tumor induction with 7, 12-dimethylbenz[a]anthracene (DMBA) as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter, papilloma multiplicity and size were decreased in the transgenic mice by 35%, and the conversion of papillomas to carcinomas was delayed. Cultured transgenic keratinocytes underwent premature senescence and upregulated transcripts for p16 and Rb but not p19 and p53. Together, these changes suggest that PML participates in regulating the growth and differentiation of keratinocytes that likely influence its activity as a suppressor for tumor development.

Burr hole drainage for complicated spontaneous intracranial hypotension syndrome.

Spontaneous intracranial hypotension is a potentially severe condition that is caused by continuous cerebrospinal fluid leakage. Clinically, most patients have a benign course and the condition remits after conservative management. We report two consecutive patients who presented with acute expansion of subdural collection and disturbed consciousness. Both patients recovered completely after undergoing burr hole drainage.

Three-dimensional reconstructed CT scanning for targeting hypertensive putaminal hemorrhage.

We developed an accurate frontal targeting method for hypertensive putaminal hemorrhage (HPH) using three-dimensional (3D) reconstructed CT scanning. Five consecutive unconscious patients with a significant volume of HPH were treated neuroendoscopically via frontal trephination. CT images were examined and reconstructed by an independent neuroradiologist for measuring the selected frontal entry point, depth of penetrating path, and surgical trajectory on the basis of the plane formed by the bilateral orbitomental lines delineated on the reconstructed 3D CT images. All patients regained consciousness post-operatively without complications. All had an accurate trajectory of penetrating path and the average percentage hematoma evacuation was 84%. Use of the 3D reconstructed CT imaging technique combined with neuroendoscopy may prove valuable as a minimally invasive and time-saving method of targeting HPH. Using this method, no further CT scanning is needed for subsequent surgical planning.

High resolution computed tomography analysis of the temporal bone.

Detailed radiological assessment by high resolution computed tomography (HRCT) of temporal bone is demanded before any temporal bone or skull base surgery. The aim of this study was to measure the relations between the anatomical landmarks of the temporal bone and to assist the otolaryngologist in establishing accurate preoperative evaluation. We enrolled 43 patients who underwent temporal bone HRCT between February 2004 and May 2004. Contiguous axial and coronal images at 1.0 mm thickness were obtained. Some landmarks such as the superior and inferior lips of the internal acoustic canal (IAC), the malleoincus joint, and the posterior semicircular canal were labeled in the coronal and axial views. Then we measured the distance between them. Average IAC diameter in the coronal and axial views was 5.33 mm and 6.92 mm. Average IAC length in the coronal and axial views was 12.29 mm and 11.09 mm. The thickness of the retrolabyrinthine bone was 3.78 mm. The incidence of thinning bone overlying the superior semicircular canal was 2.3%. Our data could be applied to normal distribution because there were no statistical differences between the measurements of normal ears and diseased ears. Several specific measurements can be applied to the preoperative evaluation of vestibular schwannoma including the retrosigmoid approach, the translabyrinthine approach and the middle fossa approach.