Much attention has been given to machine learning and its perceived impact in radiology, particularly in light of recent success with image classification in international competitions. However, ...machine learning is likely to impact radiology outside of image interpretation long before a fully functional "machine radiologist" is implemented in practice. Here, we describe an overview of machine learning, its application to radiology and other domains, and many cases of use that do not involve image interpretation. We hope that better understanding of these potential applications will help radiology practices prepare for the future and realize performance improvement and efficiency gains.
Abstract Background Brain imaging studies of early Alzheimer's disease (AD) have shown decreased metabolism predominantly in the posterior cingulate cortex (PCC), medial temporal lobe, and inferior ...parietal lobe. This study investigated functional connectivity between these regions, as well as connectivity between these regions and the whole brain. Methods Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) studies were performed in subjects with early AD, mild cognitive impairment (MCI), and normal controls. Results The data indicate both decreased fiber connections and disrupted connectivity between the hippocampus and PCC in early AD. The MCI group showed reduced fiber numbers derived from PCC and hippocampus to the whole brain. Conclusions The fMRI and DTI results confirmed decreased connectivity from both the PCC and hippocampus to the whole brain in MCI and AD and reduction in connectivity between these two regions, which plausibly represents an early imaging biomarker for AD.
Pegvisomant is a new growth hormone receptor antagonist that improves symptoms and normalises insulin-like growth factor-1 (IGF-1) in a high proportion of patients with acromegaly treated for up to ...12 weeks. We assessed the effects of pegvisomant in 160 patients with acromegaly treated for an average of 425 days.
Treatment efficacy was assessed by measuring changes in tumour volume by magnetic resonance imaging, and serum growth hormone and IGF-1 concentrations in 152 patients who received pegvisomant by daily subcutaneous injection for up to 18 months. The safety analysis included 160 patients some of whom received weekly injections and are excluded from the efficacy analysis.
Mean serum IGF-1 concentrations fell by at least 50%: 467 μg/L (SE 24), 526 μg/L (29), and 523 μg/L (40) in patients treated for 6, 12 and 18 months, respectively (p<0·001), whereas growth hormone increased by 12·5 μg/L (2·1), 12·5 μg/L (3·0), and 14·2 μg/L (5·7) (p<0·001). Of the patients treated for 12 months or more, 87 of 90 (97%) achieved a normal serum IGF-1 concentration. In patients withdrawn from pegvisomant (n=45), serum growth hormone concentrations were 8·0 μg/L (2·5) at baseline, rose to 15·2 μg/L (2·4) on drug, and fell back within 30 days of withdrawal to 8·3 μg/L (2·7). Antibodies to growth hormone were detected in 27 (16·9%) of patients, but no tachyphylaxis was seen. Serum insulin and glucose concentrations were significantly decreased (p<0·05). Two patients experienced progressive growth of their pituitary tumours, and two other patients had increased alanine and asparate aminotransferase concentrations requiring withdrawal from treatment. Mean pituitary tumour volume in 131 patients followed for a mean of 11·46 months (0·70) decreased by 0·033 cm
3(0·057; p=0·353).
Pegvisomant is an effective medical treatment for acromegaly.
We examined pituitary tumor volumes in patients treated with pegvisomant for 18 months or longer, and in whom the tumors were monitored for at least 3 years. We present details on 9 of 304 patients ...in clinical trials with pegvisomant who experienced tumor growth within the first year of treatment.
Magnetic resonance images prior to start of pegvisomant and at last follow-up were examined in 43 patients (14% of participating patients). Twenty-nine had received prior radiation therapy (18% of irradiated patients) and all but five received somatostatin analogs between periods of pegvisomant treatment.
At follow-up, the median tumor volume was 0.6 cc (range 0.0-19.7 cc), in comparison with 1.6 cc (0.0-19.7 cc) at baseline (P<0.001). Twenty-five patients, of which 23 received radiation therapy, had tumor volume reduction. Seventeen patients had no significant change. One patient, who had not received radiation therapy, had an increase in tumor volume from 1.61 to 1.93 cc. Of the nine patients with tumor growth, six had progressive growth before initiating pegvisomant. Two patients with stable tumors while on octreotide experienced enlargement after octreotide discontinuation but remained stable on long-term pegvisomant therapy.
The present data indicate that pegvisomant does not promote tumor growth and suggest that the nine observed cases of tumor progression, which occurred within 8 months after commencing pegvisomant, are likely rebound expansions after discontinuation of somatostatin analogs and/or the natural history of aggressively growing pituitary tumors. Continued long-term surveillance of tumor volume, particularly in non-irradiated patients, is recommended.
The main purpose of this study was to correlate a newly developed, simple, but comprehensive screening test for dementia called the Self Test (ST) with the Mini-mental State Examination (MMSE), and ...establish the reliability and validity of the ST.
The ST was administered to 42 consecutive new referrals to the memory clinic at the Cole Neuroscience Center, University of Tennessee Medical Center (UTMC), Knoxville, TN, U.S.A. and 41 age-matched control subjects at regular intervals over a 12-month period.
The total ST scores correlated well with cognitive severity as measured by the MMSE (r = 0.71, p < 0.01). The area under the receiver-operating characteristic curve (AUROCC) in the group of patients with Alzheimer's disease (AD) with less than a high school education was 0.80, and 0.89 in those with at least a high school education. Reliability analysis showed a mean inter-item correlation of 0.31 for patients with AD, and 0.47 for normal participants. Cronbach's alpha was calculated to be 0.70 for the AD group. Test-retest reliability was determined using intraclass correlation coefficients (ICC = 0.93, p < 0.01).
The ST is an internally consistent, reliable and valid screening test for cognitive impairment in persons exhibiting early symptoms of dementia. In addition, the ST requires minimal nonprofessional supervision and may be administered by an untrained person.
The purpose of the study was to determine the utility of anteroposterior (AP) pelvic radiographs in stable trauma patients who will undergo or have undergone abdominopelvic CT as part of the initial ...trauma imaging evaluation. Radiology reports of all stable trauma patients who underwent both abdominopelvic CT and AP pelvic radiograph from 25 January through 30 April, 2003 were reviewed for findings of acute pelvic injuries. A total of 509 consecutive patients were included in this series. Of these, 449 patients (88.2%) had no acute pelvic injury revealed by abdominopelvic CT. CT showed 163 acute injuries in 60 patients. AP radiographs showed 132 acute injuries in 52 patients. No patients with a negative CT had an acute finding on the radiograph. There were eight false-negative pelvic radiographs (negative predictive value 98.25%). CT is highly accurate in excluding acute osseous pelvic injuries. In the stable trauma patient whose CT does not reveal an acute pelvic injury or who is scheduled to undergo an abdominopelvic CT as part of the initial imaging evaluation, the pelvic radiograph may be unnecessary.
Classically in neurology, aphasia and neglect were accepted as reliable markers of cortical lesions. The actual prognostic values of aphasia and neglect have yet to be formally tested. This analysis ...sought to determine the predictive accuracy of aphasia and/or neglect in acute stroke for cortical infarction. Data from the RANTTAS investigation of tirilazad mesylate in stroke patients were reanalyzed, comparing acute National Institutes of Health Stroke Scale (NIHSS) measures of aphasia and neglect to lesion location on day 7-10 CT scans. Correlations between the presence of aphasia and/or neglect and the presence of a cortical lesion were only in the moderate range, and positive predictive values were far from perfect, as would be expected. 'Subcortical' aphasia or neglect was more likely in large, subcortical lesions. Aphasia and neglect, as determined in the acute setting by the NIHSS, are only moderately associated with cortical infarct identified on follow-up CT scans. If selective neuroprotection is envisioned for acute stroke patients, more accurate markers of cortical infarction may be needed.
Background Brain imaging studies of early Alzheimer's disease (AD) have shown decreased metabolism predominantly in the posterior cingulate cortex (PCC), medial temporal lobe, and inferior parietal ...lobe. This study investigated functional connectivity between these regions, as well as connectivity between these regions and the whole brain. Methods Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) studies were performed in subjects with early AD, mild cognitive impairment (MCI), and normal controls. Results The data indicate both decreased fiber connections and disrupted connectivity between the hippocampus and PCC in early AD. The MCI group showed reduced fiber numbers derived from PCC and hippocampus to the whole brain. Conclusions The fMRI and DTI results confirmed decreased connectivity from both the PCC and hippocampus to the whole brain in MCI and AD and reduction in connectivity between these two regions, which plausibly represents an early imaging biomarker for AD. Copyright Elsevier B.V.
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