By L. Cyrus. Belmont University.
Noncontrast CT is currently the modality of choice for detection of acute intracerebral hemorrhage order panmycin 250 mg overnight delivery. Acute hemorrhage appears hyperdense for several days due to the high protein concentration of hemoglobin and retraction of clot order panmycin 500 mg otc, but becomes progressively isodense and then hypodense over a period of weeks to months from breakdown and clearing of the hematoma by macrophages. Rarely acute hemorrhage can be isodense in severely anemic patients with a hematocrit of less than 20% or 10g/dL (10,11). Although it has been well accepted that CT can identify intra- parenchymal hemorrhage with very high sensitivity, surprisingly few studies have been conducted to support this (12,13). In 1974, shortly after the introduction of the EMI scanner, Paxton and Ambrose (14) diagnosed 66 patients with intracerebral hemorrhages with this novel modality; the study was observational, lacking autopsy conﬁrmation, and thus accuracy was not determined (insufﬁcient evidence). Subsequently, in an autopsy series of 79 patients, EMI did not detect four out of 17 patients with hem- orrhages—all were brainstem hemorrhages (limited evidence) (15). There is little doubt that the sensitivity of current third-generation CT scanners for the detection of intracerebral hemorrhage is far superior to the ﬁrst- generation scanners; however, it is of interest that the precise sensitivity and speciﬁcity of this well-accepted modality is unknown, and the level of evidence supporting its use is limited (level III). Four studies evaluating third-generation CT scanners in patients with nontraumatic subarachnoid hemorrhage identiﬁed by CT or cerebrospinal ﬂuid (CSF) have been reported (16–19). The overall sensitivity of CT was 91% to 92%, but was dependent on the time interval between symptom onset and scan time. Sensitivity was 100% (80/80) for patients imaged within 12 hours, 93% (134/144) within 24 hours, and 84% (31/37) after 24 hours (level III) (18,19). These numbers were conﬁrmed by two other studies that demonstrated a sensitivity of 98% (117/119) for scans obtained within 12 hours, 95% (1313/1378) within 24 hours, 91% (1247/1378) between 24 and 48 hours, and 74% after 48 hours (1017/1378) (moderate evidence) (16,17). These studies relied on a diagnosis made by CT, or by blood detected in CSF in the absence of CT ﬁndings. Therefore, although CT is commonly regarded as the modality of choice for imaging intracranial hemorrhage, the precise sensitivity and speciﬁcity is unknown and is dependent on time after onset, concentration of hemo- globin, and size and location of the hemorrhage (limited evidence). Magnetic Resonance Imaging Like CT, the appearance and detectability of hemorrhage on magnetic res- onance imaging (MRI) depends on the age of blood and the location of the hemorrhage (intraparenchymal or subarachnoid). In addition, the strength of the magnetic ﬁeld, and type of MR sequence inﬂuences its sensitivity (20). As the hematoma ages, oxyhemoglobin in blood breaks down sequen- tially into several paramagnetic products: ﬁrst deoxyhemoglobin, then methemoglobin, and ﬁnally hemosiderin.
Equations for calculating the results in the previous examples are listed in Appendix 1 discount panmycin 500 mg with visa. Qualitative literature summary The keystone of the evidence-based imaging (EBI) approach is to critically assess the research data that are provided and to determine if the infor- mation is appropriate for use in answering the EBI question buy panmycin 500 mg overnight delivery. Unfortunately, the published studies are often limited by bias, small sample size, and methodological inadequacy. Further, the information provided in pub- lished reports may be insufﬁcient to allow estimation of the quality of the research. Two recent initiatives, the CONSORT (1) and STARD (2), aim to improve the reporting of clinical trials and studies of diagnostic accuracy, respectively. This chapter summarizes the common sources of error and bias in the imaging literature. Random error occurs due to chance variation, causing a sample to be different from the underlying population. Systematic error, or bias, is an incorrect study result due to nonrandom distortion of the data. Using the bull’s-eye analogy, the larger the sample size, the less the random error and the larger the chance of hitting the center of the target. In systematic error, regardless of the sample size, the bias would not allow the researcher to hit the center of the target. A second way to think about random and sys- tematic error is in terms of precision and accuracy (3). The larger the sample size, the more precision in the results and the more likely that two samples from truly different populations will be differentiated from each other. Using the bull’s-eye analogy, the larger the sample size, the less the random error and the larger the chance of hitting the center of the target (Fig.
Because not all couples have difficulties with all parts of early marital adjustment cheap panmycin 250mg line, il- lustrations are taken from a variety of cases buy panmycin 250 mg on-line. Next, reference is made to some issues typically found in therapy with mainstream White American couples and couples from other ethnic, racial, and religious backgrounds. The majority of extant research literature deals with differences between White Americans and African American or Hispanic couples. Napier has succinctly stated, "Mar- riage involves learning to be both separate and together, learning to allo- cate power, learning to play and to work together, and [for some] perhaps the greatest challenge of all, learning to rear another generation" (2000, p. Lewin expressed it decades ago as follows: Manifold needs are generally expected to be satisfied in and through mar- riage... Which of these needs are dominant, which are fully satisfied, and which are not at all satisfied, depend upon the personality of the marriage partners, and upon the setting in which the particular marriage group lives. A distinction made by Kan- tor and Lehr (1975) is helpful in understanding some of the essential differ- ences between the dependency relationship we are involved in with our parents during our formative years and the intimacy in a healthy, adult rela- tionship with a spouse. They distinguish between intimacy and nurturance, defining intimacy as a condition of mutual emotional and often intense closeness among peers. Nurturance, instead of being a two-directional emo- tional exchange, "implies a primarily unidirectional flow of affect" (Kantor & Lehr, 1975, p. As with other parts of marriage, workable, appropriate intimacy is not easily attainted. Persons may have different "social distances": Willingness to marry is considered a symptom of desire for the least social distance. Indeed, marriage means the willingness to share activities and situations that otherwise are kept strictly private. Married life includes permanent physical proximity brought to a climax in the sex relationship. Marriage is the lone voluntary family relationship (Napier, 1988; Nichols, 1988, 1996, 2000).