Investigating the superhydrophobic behavior for underwater surfaces using impedance-based methods.

We have investigated the impedance behavior of immersed superhydrophobic (SH) polymethylene surfaces by tailoring the surface tension of the contacting liquid phase to gradually transition the surface from the Cassie to the Wenzel state. Control over the surface tension is accomplished by varying the ethanol content of the aqueous phase. To establish the mechanism of the transition, we imaged the interface of the film and identified three distinct events of this process: a nucleation event at low concentrations of ethanol in which small areas beneath the liquid phase transition into the Wenzel state, a propagation event characterized by the enlargement of the Wenzel domains and the lateral displacement of air, and a final event at higher concentrations of ethanol in which the thin air layer at the interface morphs into isolated pockets of air. Using this visualization of the transition, we characterized the Cassie and the Wenzel states by measuring the impedance at a frequency of 1 kHz for an initially SH film that changes its wetting behavior upon addition of ethanol. Establishment of the Cassie and Wenzel state conditions was based on concepts of electrochemical impedance spectroscopy (EIS) and quantitatively validated using both the Helmholtz theory and the analytical description of the electrochemical system in terms of the circuit model of a metal surface covered by a polymer film. Finally, we apply this strategy to determine the possibility for SH polymethylene (PM) films to reversibly transition between the Cassie and the Wenzel states. Results show that after rinsing and drying at ambient conditions for 24 h, the film recovers the SH state, suggesting the applicability of these SH films in outdoor environments with occasional periodic submersion in water.

Novel use of hepatobiliary scintigraphy for the diagnosis of interleukin-2 cholangiopathy.

We report a case of interleukin-2 (IL-2) induced cholangiopathy diagnosed with the aid of hepatobiliary scintigraphy. Patient was a 32 years old, male with history of metastatic melanoma. Computed tomography (CT) upon admission demonstrated worsening of patient's metastatic lung disease with a normal appearance of the gallbladder. The patient was started on high dose IL-2 treatment for regression of his disease. Four days after IL-2 treatment was begun, the patient developed severe right upper quadrant pain and elevated liver function tests. A right upper quadrant ultrasound and surgical consultation were requested. Sonographic findings demonstrated diffuse gallbladder wall thickening, mural edema, a positive sonographic Murphy's sign, but no gallstones. The preliminary working diagnosis was acalculous cholecystitis versus IL-2 induced cholangiopathy. To clarify between these two entities, a hepatobiliary scan was obtained that demonstrated filling of the gallbladder with prompt biliary-to-bowel transit and normal liver function. In this case, the clinical presentation and history of recent IL-2 treatment were suggestive of IL-2 cholangiopathy, though the patient's co-morbidities and in-patient status raised concern for acalculous cholecystitis. Given the marked differences in treatment, hepatobiliary imaging was requested and found to be normal, making acalculous cholecystitis very unlikely. In conclusion, we believe this is the first case in which hepatobiliary scintigraphy was used to aid in the diagnosis of IL-2 induced cholangiopathy.

Prognostic effect of pathologic fracture in localized osteosarcoma: a cohort/case controlled study at a single institute.

BACKGROUND: The negative prognostic role of pathologic fracture in osteosarcoma is not determined, as previous case-control and retrospective cohort studies have produced contradictory results. METHODS: We conducted both cohort (n = 384) and case-control (n = 111) studies on 37 pathologically fractured localized osteosarcoma of extremity. RESULTS: In cohort study, patients with a fracture showed a tendency of poorer survival, but the difference did not reach the level of significance (5-year metastasis-free survival rates; 48% for cases vs. 61% for controls; P = 0.06). A case-control study on 37 fractured and 74 control recruited from 347 patients matched for tumor size and location showed no survival difference between the cases and controls (P = 0.12). CONCLUSIONS: Reported negative prognostic effect of a pathologic fracture is likely to be due to confounding by tumor size and location. The present study suggests that the presence of a pathologic fracture has no prognostic relevance.

Comparison of planar scintigraphy alone and with SPECT for the initial evaluation of femoral neck stress fracture.

OBJECTIVE: The objective of our study was to compare the accuracy of planar scintigraphy alone versus planar scintigraphy with SPECT for the initial evaluation of femoral neck stress fractures in a young military population. MATERIALS AND METHODS: We retrospectively identified 38 patients who had undergone planar scintigraphy and 33 patients who had undergone planar scintigraphy and SPECT before MRI of the hips over a 6-month period for evaluation of suspected femoral neck fracture. Data were analyzed regarding the sensitivity and specificity of bone scanning alone and with SPECT for detecting femoral neck stress fracture and grading fractures as low grade (grades I and II) or high grade (grades III and IV). RESULTS: Twelve fractures were identified in the group who underwent planar scintigraphy alone and 13 in the group who underwent planar scintigraphy with SPECT. The sensitivities of planar scintigraphy alone and with SPECT were 50% and 92.3%, respectively (p = 0.03). The accuracy of each technique for the detection of high-grade fractures was 12.5% and 70%, respectively (p = 0.025). CONCLUSION: Planar scintigraphy with SPECT had a higher sensitivity and accuracy in assessing the grade of femoral neck stress fractures than planar scintigraphy alone. The results of this study suggest that SPECT should be performed with planar bone scintigraphy for the evaluation of patients with suspected femoral neck stress fractures.

The "hot nose" sign on brain death nuclear scintigraphy: where does the flow really go?

Nuclear scintigraphy has been used in patients with brain death since the 1970s. Many studies report a "hot nose" sign as predictive of brain death and lack of cerebral flow. Current nuclear medicine textbooks state that increased flow to the nose occurs secondary to occlusion of the internal carotid artery with flow rerouted to the nose via the external carotid artery. This explanation has been provided for decades assuming that the blood flow is actually increased to the nose. We performed a study to determine whether flow is really seen in the nose when a hot nose sign is present.

Instruction of hospitalized patients by respiratory therapists on metered-dose inhaler use leads to decrease in patient errors.

BACKGROUND: Hospitalized patients have been shown to make several errors in using metered-dose inhalers (MDIs), which can lead to poor medication delivery. METHODS: This study was designed to look at the potential benefit of a respiratory therapist (RT) giving instruction on the use of MDIs to hospitalized patients with obstructive lung disease. A baseline group of 58 patients was observed by a physician while performing 2 actuations of their MDI and the number of errors they committed, based on the National Institutes of Health's recommended 8 steps for proper MDI use, was recorded. After a program of MDI instruction (which included encouragement to use a spacer) by an RT was performed, a second group of hospitalized patients was again observed by a physician to determine if their error rate was reduced. RESULTS: The baseline error rate was 6.72 (out of 15 possible) errors per patient, and improved to 2.43 errors per patient after RT-provided instruction (p < 0.001). This improvement was still significant after controlling for an increased use of spacers in the post-instruction group of patients (27.6% and 91.7% spacer use before and after education). CONCLUSIONS: Instruction of hospitalized patients with obstructive lung disease by an RT improves their correct use of MDIs and increases their use of spacers while in the hospital.

Using electrophysiology to demonstrate that cueing affects long-term memory storage over the short term.

As researchers who study working memory, we often assume that participants keep a representation of an object in working memory when we present a cue that indicates that the object will be tested in a couple of seconds. This intuitively accounts for how well people can remember a cued object, relative to their memory for that same object presented without a cue. However, it is possible that this superior memory does not purely reflect storage of the cued object in working memory. We tested the hypothesis that cues presented during a stream of objects, followed by a short retention interval and immediate memory test, can change how information is handled by long-term memory. We tested this hypothesis by using a family of frontal event-related potentials believed to reflect long-term memory storage. We found that these frontal indices of long-term memory were sensitive to the task relevance of objects signaled by auditory cues, even when the objects repeated frequently, such that proactive interference was high. Our findings indicate the problematic nature of assuming process purity in the study of working memory, and demonstrate that frequent stimulus repetitions fail to isolate the role of working memory mechanisms.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies.

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.

Unexpected uptake of gadoxetic acid in a hepatic metastasis from T-cell lymphoma.

We report a case of unexpected heterogeneous uptake of gadoxetic acid into a hepatic metastasis in a patient with T-cell lymphoblastic lymphoma that also lacked hypermetabolic characteristics on positron emission (PET)/computed tomography (CT) with [(18)F]fluorodeoxyglucose (FDG). Therefore, in cases of heterogeneous uptake of gadoxetic acid, infiltrative lesions must be considered.

Limitations of dual time point PET in the assessment of lung nodules with low FDG avidity.

FDG PET has long shown efficacy in the evaluation of indeterminate pulmonary nodules. More recently, the use of dual time point imaging has been looked at as a means for improving sensitivity and accuracy. While initial reports were very promising, more recent results looking specifically at pulmonary lesions with low levels of FDG avidity demonstrated limitations. These lesions (initial maximum standard uptake value of less than 2.5) are of particular interest due to the fact that well-differentiated adenocarcinomas, broncheoaveolar carcinoma and carcinoid may have low FDG avidity on standard PET imaging, leading to false-negative exams. Our study retrospectively reviewed the accuracy of dual time point (DTP) FDG PET imaging to determine if it aided in the identification of malignant pulmonary nodules when initial time point imaging showed a maximum SUV of less than 2.5. 113 patients had undergone a total of 130 DTP PET/CT with 152 lesions assessed. 67 lesions were subsequently definitively diagnosed as benign or malignant based upon biopsy or imaging follow-up. Utilizing a maximum SUV increase of 10%, which optimizes our sensitivity and specificity; our results demonstrate a sensitivity of 63% and a specificity of 59%, similar to other investigators evaluating lesions with low FDG avidity. Increasing or decreasing this threshold did not improve our results, nor did the addition of lesions with maximum SUV's of 2.5 or greater on initial imaging. Specifically in nodules with low FDG avidity (max SUV<2.5), the sensitivity was 61%, specificity 58%, and accuracy was 60%. Our findings suggest that DTP FDG PET may not be of benefit in the assessment of pulmonary nodules with maximum SUV of less than 2.5 on initial imaging.

Normal organ standard uptake values in carbon-11 acetate PET imaging.

OBJECTIVE: The goal of this study was to determine normal standard uptake values of carbon-11 (11C) acetate in healthy organs. By accurately determining the range of physiologic activity, abnormal focal or diffuse 11C-acetate activity can be more accurately assessed and thus improve the sensitivity and specificity of this emerging diagnostic PET agent. METHODS: We reviewed all 55 patients (mean age+/-SD 64.8+/-10.8, age range 35-88 years) who underwent 11C-acetate PET/computed tomography at our institution from 2005 to 2007. Regions of interest were drawn in organs that were devoid of clinical or imaging evidence of disease. The maximum standard uptake value for each region was calculated and analyzed for mean, standard deviation, and 95% confidence intervals. RESULTS: The results are presented as average maximum standard uptake value+/-1 SD with the pancreas, liver, spleen and salivary glands showing the greatest 11C-acetate avidity. A review of the literature shows our results to be similar to those published earlier. CONCLUSION: Accurate knowledge of normal biodistribution and standardized uptake values will provide the foundation for assessing focal or diffuse organ disease while using this PET agent.

Acetabular impingement on planar and SPECT bone scintigraphy.

A 37-year-old male presented with 4 months of atraumatic left hip pain. Onset of symptoms began during basic military training and pain was exacerbated by physical activity. Plain film radiographs of the hip were reported as normal. Because of the concern for a potential stress fracture, the patient was referred to nuclear medicine for bone scintigraphy. Planar and SPECT imaging revealed the presence of abnormal scintigraphic activity involving both hips (left greater than right) in a distribution atypical for stress injury and more consistent with bilateral femoral acetabular impingement (FAI). Subsequent MR examination was confirmed the diagnosis. This case illustrates a novel method for evaluating the physiologic process of FAI.