Interpretation of radiological images: towards a framework of knowledge and skills

The knowledge and skills that are required for radiological image interpretation are not well documented, even though medical imaging is gaining importance. This study aims to develop a comprehensive framework of knowledge and skills, required for two-dimensional and multiplanar image interpretation in radiology. A mixed-method study approach was applied. First, a literature search was performed to identify knowledge and skills that are important for image interpretation. Three databases, PubMed, PsycINFO and Embase, were searched for studies using synonyms of image interpretation skills or visual expertise combined with synonyms of radiology. Empirical or review studies concerning knowledge and skills for medical image interpretation were included and relevant knowledge and skill items were extracted. Second, a preliminary framework was built and discussed with nine selective experts in individual semi-structured interviews. The expert team consisted of four radiologists, one radiology resident, two education scientists, one cognitive psychologist and one neuropsychologist. The framework was optimised based on the experts comments. Finally, the framework was applied to empirical data, derived from verbal protocols of ten clerks interpreting two-dimensional and multiplanar radiological images. In consensus meetings adjustments were made to resolve discrepancies of the framework with the verbal protocol data. We designed a framework with three main components of image interpretation: perception, analysis and synthesis. The literature study provided four knowledge and twelve skill items. As a result of the expert interviews, one skill item was added and formulations of existing items were adjusted. The think-aloud experiment showed that all knowledge items and three of the skill items were applied within all three main components of the image interpretation process. The remaining framework items were apparent only within one of the main components. After combining two knowledge items, we finally identified three knowledge items and thirteen skills, essential for image interpretation by trainees. The framework can serve as a guideline for education and assessment of two- and three-dimensional image interpretation. Further validation of the framework in larger study groups with different levels of expertise is needed.     

Subjective health in spinal cord injury after outpatient healthcare follow-up

OBJECTIVE: To compare self-reported health, independence, and depression in two samples of people with spinal cord injury (SCI), one which receives regular, comprehensive outpatient health care follow-up and one that does not. DESIGN: Exploratory study of self-reported secondary conditions in 235 individuals with SCI who received health care follow-up using post hoc quasi-experimental comparisons with a group of 136 people with SCI who had no health care follow-up. SETTING: Outpatients at a Veterans Affairs Health Care System SCI Center. MAIN OUTCOME MEASURES: The Check Your Health Instrument surveyed three self-report measures: overall health, independence, and depression. The Secondary Conditions Screening Instrument (SCSI) addressed 40 secondary conditions that may have been experienced in the prior year. RESULTS: Study participants who receive ongoing SCI health care reported higher subjective health, independence, and absence of depression scores compared to those that did not receive regular SCI health care follow-up. Results on the SCSI showed similar secondary conditions in the two groups, but higher frequency and severity in the no follow-up group. CONCLUSION: SCI outpatient health care follow-up is associated with higher subjective health, independence, and absence of depression.     

Role of Ca2+-Activated Cl− Current in Ventricular Action Potentials of Sheep During Adrenoceptor Stimulation

Adrenoceptor stimulation enhances repolarising and depolarising membrane currents to different extents in cardiac myocytes. We investigated the opposing effects of the repolarising Ca(2+)-activated Cl(-) current (I(Cl(Ca))) and depolarising L-type Ca(2+) current (I(Ca,L)) on the action potential configuration of sheep ventricular myocytes stimulated with noradrenaline. Whole-cell current-clamp recordings revealed that noradrenaline accelerated and prolonged phase-1 repolarisation. We define the minimal potential at the end of phase-1 repolarisation as "notch level". Noradrenaline (1 microM) caused the notch level to fall from 14 +/- 2.6 to 7.8 +/- 2.8 mV (n = 24), but left action potential duration, resting membrane potential or action potential amplitude unaffected. Whole-cell voltage-clamp recordings showed that 1 microM noradrenaline increased both I(Ca,L) and I(Cl(Ca)), but it had no significant effect on the principal K(+) currents. Blockage of I(Cl(Ca)) by 0.5 mM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) in both the absence and the presence of noradrenaline abolished phase-1 repolarisation. In the presence of noradrenaline, DIDS caused elevation of the plateau phase amplitude and an increase in the action potential duration. In conclusion, elevation of the plateau phase amplitude and action potential prolongation associated with an increased I(Ca,L) upon adrenoceptor stimulation is prevented by an increased I(Cl(Ca)) in sheep ventricular myocytes. Experimental Physiology (2001) 86.2, 151-159.     

High-conductance anion channels in embryonic chick osteogenic cells.

Patch-clamp measurements done on excised membrane patches obtained from 1-5 day cultured embryonic chick osteoblasts, osteocytes, and periosteal fibroblasts revealed the existence of a high-conductance anion channel: 371 +/- 63 pS when measured under symmetrical 158 mM Cl- conditions. The channel frequently displayed subconductance levels. The ion selectivity of the channel expressed as the (an)ion to chloride permeability ratio was as follows: Cl- (1.0) greater than methylsulfate- (0.71) greater than gluconate- (0.25) greater than glutamate- (0.17) greater than Na+ = K+ (0.10). In addition, the channel had a significant permeability for inorganic phosphate ions. The channel was found in about 1% of the cell-attached patches, which indicates that the channel is under the control of as yet unknown intracellular factors. Once activated by patch excision, the channel was voltage dependent and active at potentials close to 0 mV. At potentials outside the range of +/- 10 mV channel activity decreased. This process proceeded faster at increasing membrane potentials of either polarity. Returning to potentials close to 0 mV caused reopening of the channels within seconds if the preceding voltage step led to complete closure of the channels. Channel activity did not depend noticeably on intracellular and extracellular CA2+ ions. The channel is not unique to (chick) osteogenic cells but has been demonstrated in excised patches obtained from excitable and other nonexcitable cells. Although its presence in a wide variety of cell types suggests that the channel plays a general role in as yet unknown cell physiologic processes, the channel may also have specific functions in osteogenic cells, for example providing a pathway for phosphate ions during mineralization.     

Effects of muscarinic receptor stimulation on Ca2+ transient, cAMP production and pacemaker frequency of rabbit sinoatrial node cells

We investigated the contribution of the intracellular calcium (Ca _i ²⁺ ) transient to acetylcholine (ACh)-mediated reduction of pacemaker frequency and cAMP content in rabbit sinoatrial nodal (SAN) cells. Action potentials (whole cell perforated patch clamp) and Ca _i ²⁺ transients (Indo-1 fluorescence) were recorded from single isolated rabbit SAN cells, whereas intracellular cAMP content was measured in SAN cell suspensions using a cAMP assay (LANCE^®). Our data show that the Ca _i ²⁺ transient, like the hyperpolarization-activated “funny current” (I _f) and the ACh-sensitive potassium current (I _K,ACh), is an important determinant of ACh-mediated pacemaker slowing. When I _f and I _K,ACh were both inhibited, by cesium (2 mM) and tertiapin (100 nM), respectively, 1 μM ACh was still able to reduce pacemaker frequency by 72%. In these I _f and I _K,ACh-inhibited SAN cells, good correlations were found between the ACh-mediated change in interbeat interval and the ACh-mediated change in Ca _i ²⁺ transient decay (r ² = 0.98) and slow diastolic Ca _i ²⁺ rise (r ² = 0.73). Inhibition of the Ca _i ²⁺ transient by ryanodine (3 μM) or BAPTA-AM (5 μM) facilitated ACh-mediated pacemaker slowing. Furthermore, ACh depressed the Ca _i ²⁺ transient and reduced the sarcoplasmic reticulum (SR) Ca²⁺ content, all in a concentration-dependent fashion. At 1 μM ACh, the spontaneous activity and Ca _i ²⁺ transient were abolished, but completely recovered when cAMP production was stimulated by forskolin (10 μM) and I _K,ACh was inhibited by tertiapin (100 nM). Also, inhibition of the Ca _i ²⁺ transient by ryanodine (3 μM) or BAPTA-AM (25 μM) exaggerated the ACh-mediated inhibition of cAMP content, indicating that Ca _i ²⁺ affects cAMP production in SAN cells. In conclusion, muscarinic receptor stimulation inhibits the Ca _i ²⁺ transient via a cAMP-dependent signaling pathway. Inhibition of the Ca _i ²⁺ transient contributes to pacemaker slowing and inhibits Ca _i ²⁺ -stimulated cAMP production. Thus, we provide functional evidence for the contribution of the Ca _i ²⁺ transient to ACh-induced inhibition of pacemaker activity and cAMP content in rabbit SAN cells.     

Changing stage of readiness for physical activity in Medicaid beneficiaries with physical impairments

People with disabilities are more sedentary than the general population, putting them at risk for secondary conditions like diabetes. This study investigated the effectiveness of motivational interviewing (MI) for changing stage of readiness for physical activity, taking into account baseline stage of readiness and participation barriers. Study participants (n = 139 non-institutionalized, disabled Medicaid beneficiaries) were randomly assigned to either the treatment condition (MI) or a control condition (newsletter). Individuals receiving MI were more likely to move into the preparation stage of readiness (OR = 3.13). Regardless of treatment condition, individuals in the contemplation stage at baseline were more likely to move into preparation (OR = 5.53) and action stage (OR = 8.89). With regard to participation barriers, each unit increase in participants' ratings predicted a 4% to 5% reduction in likelihood of moving into either the preparation or action stage of readiness.     

The undervalued potential of positional therapy in position-dependent snoring and obstructive sleep apnea—a review of the literature

Purpose

Research during the past 10–20 years shows that positional therapy (PT) has a significant influence on the apnea–hypopnea index. These studies are predominantly performed as case series on a comparably small number of patients. Still, results have not found their way into the daily diagnostic and treatment routine. An average of 56?% of patients with obstructive sleep apnea (OSA) have position-dependent OSA (POSA), commonly defined as a difference of 50?% or more in apnea index between supine and non-supine positions. A great deal could be gained in treating patients with POSA with PT. The aim of this paper was to perform a thorough review of the literature on positional sleep apnea and its therapy.

Methods

A broad search strategy was run electronically in the MEDLINE and EMBASE databases using synonyms for position and sleep apnea.

Results

Sixteen studies were found which examined the effect of PT on OSA. In this literature review, we discuss the various techniques, results, and compliance rates.

Conclusion

Long-term compliance for PT remains an issue, and although remarkable results have been shown using innovative treatment concepts for PT, there is room for both technical improvement of the devices and for further research.     

Evaluation of a new simple treatment for positional sleep apnoea patients

Obstructive sleep apnoea syndrome is a common clinical problem. Positional sleep apnoea syndrome, defined as having a supine apnoea-hypopnoea index of twice or more compared to the apnoea-hypopnoea index in the other positions, occurs in 56% of obstructive sleep apnoea patients. A limited number of studies focus on decreasing the severity of sleep apnoea by influencing sleep position. In these studies an object was strapped to the back (tennis balls, squash balls, special vests), preventing patients from sleeping in the supine position. Frequently, this was not successful due to arousals while turning from one lateral position to the other, thereby disturbing sleep architecture and sleep quality. We developed a new neck-worn device which influences sleep position by offering a vibration when in supine position, without significantly reducing total sleep time. Thirty patients with positional sleep apnoea were included in this study. No side effects were reported. The mean apnoea-hypopnoea index dropped from 27.7 ± 2.4 to 12.8 ± 2.2. Seven patients developed an overall apnoea-hypopnoea index below 5 when using the device in ON modus. We expect that positional therapy with such a device can be applied as a single treatment in many patients with mild to moderate position-dependent obstructive sleep apnoea, while in patients with a more severe obstructive sleep apnoea such a device could be used in combination with other treatment modalities.     

Ca2+‐activated Cl− current reduces transmural electrical heterogeneity within the rabbit left ventricle

Objective: Various cationic membrane channels contribute to the heterogeneity of action potential configuration between the transmural layers of the left ventricle. The role of anionic membrane channels is less intensively studied. We investigated the role of the Ca²⁺‐activated Cl^? current, I_Cl(Ca), in transmural electrical heterogeneity. Methods and Results: We determined the density of I_Cl(Ca) and its physiological role in subepicardial and subendocardial ventricular myocytes of rabbit using the patch‐clamp technique. I_Cl(Ca) was measured as the 4,4′diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS) sensitive current. The current–voltage relationships and the densities of I_Cl(Ca) were similar in subepicardial and subendocardial myocytes. However, the functional role of I_Cl(Ca) exhibited striking differences. In subendocardial myocytes, blockade of I_Cl(Ca) by DIDS increased action potential duration (APD) significantly at all measured stimulus frequencies (3.33–0.2 Hz). In subepicardial myocytes, I_Cl(Ca) blockade increased APD only at 3.33 Hz, but not at the lower stimulus frequencies. At 1 Hz, I_Cl(Ca) blockade in subepicardial myocytes only caused an APD increase when the transient outward K⁺ current, I_to1, was blocked. Conclusions: The densities and gating properties of I_Cl(Ca) are similar in subepicardial and subendocardial myocytes. I_Cl(Ca) contributes to APD shortening in subendocardial, but not in subepicardial myocytes except at 3.33 Hz. These differences in functional expression of I_Cl(Ca) reduce the electrical heterogeneity in rabbit left ventricle.