Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Q: Context: Complications after immediate breast reconstruction pose a significant challenge to the reconstructive surgeon. Known risk factors include smoking, obesity, age, and adjuvant oncologic therapies. Less is known about the association between axillary lymph node dissection (ALND) and the development of postoperative complications.', 'We conducted a retrospective study of all patients who underwent immediate breast reconstruction after mastectomy at our institution over a 10-year period. Our outcome was an occurrence of a major complication within 90 days postoperatively. For each patient, we recorded data on demographics, smoking status, pertinent medical history, reconstruction type, adjuvant chemotherapy and radiation, tumor pathology, and whether an ALND was performed. Odds ratios (OR) were calculated to estimate the risk of a complication if an ALND was performed.', 'One hundred eighty-four women, with 270 surgically treated breasts, were identified as having mastectomy with immediate reconstruction between 2002 and 2012. Mean age was 49.4 years (range, 25-84 years). There were 71 mastectomies with ALND performed, with 22 complications, and 199 mastectomies without ALND, with 20 complications (31% complication rate vs 10%, respectively; OR, 3.84; P < 0.001). When adjusted for reconstruction type, smoking history, obesity, age, presence of invasive disease, chemotherapy, and radiation therapy, the OR for complications was 3.49 (P < 0.01). The most common complication was infection in both groups.
Answer: Mastectomy with ALND is associated with a 3-fold increase in risk of major complications in women undergoing immediate breast reconstruction, even after adjustment for known risk factors and confounders. Further studies are warranted to elucidate how ALND leads to these complications and what measures can reduce their occurrence.

A: Does axillary Lymph Node Dissection be a Risk Factor for Major Complications After Immediate Breast Reconstruction?
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Q: Context: 99mTc-HMPAO is a well-established isotope useful in the detection of regional cerebral blood flow. Diabetes gives rise to arterial atherosclerotic changes that can lead to significant end organ dysfunction, prominently affecting perfusion to the heart, kidneys, eyes and brain. In the current study, we investigated the role of 99mTc-HMPAO cerebral perfusion scans in detecting early vascular changes in the diabetic brain.', 'Cerebral perfusion studies were performed on both control and streptozotocin-(STZ) induced diabetic male Wistar rats. Rat brain imaging using a gamma camera was performed for each group 0.5, 2, 4, and 24 hours post 99mTc-HMPAO injection. Data processing for each cerebral perfusion scan was performed by drawing a region of interest (ROI) circumferentially around the brain (B). Background (BKG) due to signal from the soft tissue of each rat was subtracted. Brain 99mTc-HMPAO uptake minus background counts (net brain counts; NBC) were then compared between the two groups.', 'The NBC (mean +/- SD) for the STZ group were statistically significantly higher (p = 0.0004) than those of the control group at each of the time points studied.
Answer: 99mTc-HMPAO brain scan may be useful in the detection of early atherosclerotic changes in the diabetic rat brain.

A: Does perfusion scanning using 99mTc-HMPAO detect early cerebrovascular changes in the diabetic rat?
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Q: Context: Mild cognitive impairment (MCI) is recognized as a predementia state, but its definition is inconsistent and only 20%-30% develop dementia after 2 years. Biomarkers may help identify individuals at greatest risk of progressive decline. The authors examine a novel neuroimaging technique, diffusion tensor imaging (DTI) as a potential biomarker of MCI.', 'Cross-sectional prospective study.', 'Subjects were recruited randomly using the electoral roll from two electorates in East Sydney, Australia.', 'A community-dwelling sample (N = 249) and age 70-90 years.', 'Screening to exclude dementia, comprehensive neuropsychiatric assessment, cognitive test battery, structural magnetic resonance imaging and DTI to obtain measures of fractional anisotropy (FA) and mean diffusivity (MD). MCI was diagnosed by standard criteria.', 'After controlling for age, sex, and years of education, the amnestic MCI (aMCI) group demonstrated microstructural pathology in the parahippocampal white matter, frontal white matter, splenium of corpus callosum, and posterior cingulate region. The nonamnestic MCI (naMCI) group demonstrated microstructural pathology in the frontal white matter, internal capsule, occipital white matter, and the posterior cingulate region. A binary logistic regression model showed that DTI of the left posterior cingulate was significant in identifying persons with aMCI to an accuracy of 85.1%. Receiver operating characteristics curve analysis yielded a sensitivity of 80% and specificity of 60.3% in distinguishing aMCI from naMCI and the normal comparison group.
Answer: DTI of the posterior cingulate region discriminates MCI from cognitively normal individuals with accuracy and has the potential to be used as a biomarker of MCI, in particular aMCI.

A:
Is diffusion tensor imaging of the posterior cingulate a useful biomarker of mild cognitive impairment?
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