Surveillance of Unruptured Intracranial Saccular Aneurysms Using Noncontrast 3D-Black-Blood MRI: Comparison of 3D-TOF and Contrast-Enhanced MRA with 3D-DSA.

BACKGROUND AND PURPOSE: Patients with unruptured intracranial aneurysms routinely undergo surveillance imaging to monitor growth. Angiography is the criterion standard for aneurysm diagnosis, but it is invasive. This study aimed to evaluate the accuracy and reproducibility of a 3D noncontrast black-blood MR imaging technique for unruptured intracranial aneurysm measurement in comparison with 3D-TOF and contrast-enhanced MRA, using 3D rotational angiography as a reference standard. MATERIALS AND METHODS: Sixty-four patients (57.3 ± 10.9 years of age, 41 women) with 68 saccular unruptured intracranial aneurysms were recruited. Patients underwent 3T MR imaging with 3D-TOF-MRA, 3D black-blood MR imaging, and contrast-enhanced MRA, and they underwent 3D rotational angiography within 2 weeks. The neck, width, and height of the unruptured intracranial aneurysms were measured by 2 radiologists independently on 3D rotational angiography and 3 MR imaging sequences. The accuracy and reproducibility were evaluated by Bland-Altman plots, the coefficient of variance, and the intraclass correlation coefficient. RESULTS: 3D black-blood MR imaging demonstrates the best agreement with DSA, with the smallest limits of agreement and measurement error (coefficients of variance range, 5.87%-7.04%). 3D-TOF-MRA had the largest limits of agreement and measurement error (coefficients of variance range, 12.73%-15.78%). The average coefficient of variance was 6.26% for 3D black-blood MR imaging, 7.03% for contrast-enhanced MRA, and 15.54% for TOF-MRA. No bias was found among 3 MR imaging sequences compared with 3D rotational angiography. All 3 MR imaging sequences had excellent interreader agreement (intraclass correlation coefficient, >0.95). 3D black-blood MR imaging performed the best for patients with intraluminal thrombus (n = 10). CONCLUSIONS: 3D black-blood MR imaging achieves better accuracy for aneurysm size measurements compared with 3D-TOF, using 3D rotational angiography as a criterion standard. This noncontrast technique is promising for surveillance of unruptured intracranial aneurysms.

Clinical Significance of Intraplaque Hemorrhage in Low- and High-Grade Basilar Artery Stenosis on High-Resolution MRI.

BACKGROUND AND PURPOSE: Intraplaque hemorrhage within intracranial atherosclerotic plaques identified by high-resolution MR imaging has been studied as a potential marker of stroke risk. However, previous studies only examined intracranial arteries with high-grade stenosis (degree of stenosis, >50%). This study aimed to ascertain the clinical relevance of intraplaque hemorrhage in patients with low- and high-grade stenotic basilar artery plaques. MATERIALS AND METHODS: Patients with basilar artery stenosis (n = 126; mean age, 62 ± 10 years; 66 symptomatic and 60 asymptomatic) underwent high-resolution MR imaging. The relationship between imaging findings (intraplaque hemorrhage, contrast enhancement, degree of stenosis, minimal lumen area, and plaque burden) and symptoms was analyzed. RESULTS: Intraplaque hemorrhage was identified in 22 patients (17.5%), including 21 (31.8%) symptomatic patients and 1 (1.7%) asymptomatic patient. Multivariate analysis showed that intraplaque hemorrhage was the strongest independent marker of symptomatic status (odds ratio, 27.5; 95% CI, 3.4-221.5; P = .002). Contrast enhancement was also independently associated with symptomatic status (odds ratio, 9.9; 95% CI, 1.5-23.6; P = .016). Stenosis, minimal lumen area, and plaque burden were not correlated with symptoms (P > .05). Intraplaque hemorrhage was present in both low- and high-grade stenotic basilar arteries (11.3% versus 16.3%, P = .63). Diagnostic performance values of intraplaque hemorrhage for patients with acute/subacute symptomatic stroke were the following: specificity, 98.3%; sensitivity, 31.8%; positive predictive value, 95.5%; and negative predictive value, 56.7%. CONCLUSIONS: Intraplaque hemorrhage is present in both low- and high-grade stenotic basilar artery plaques and is independently associated with symptomatic stroke status. Intraplaque hemorrhage may identify high-risk plaque and provide new insight into the management of patient with stroke without significant stenosis.

Identification and Quantitative Assessment of Different Components of Intracranial Atherosclerotic Plaque by Ex Vivo 3T High-Resolution Multicontrast MRI.

BACKGROUND AND PURPOSE: High-resolution 3T MR imaging can visualize intracranial atherosclerotic plaque. However, histologic validation is still lacking. This study aimed to evaluate the ability of 3T MR imaging to identify and quantitatively assess intracranial atherosclerotic plaque components ex vivo with histologic validation. MATERIALS AND METHODS: Fifty-three intracranial arterial specimens with atherosclerotic plaques from 20 cadavers were imaged by 3T MR imaging with T1, T2, and proton-density-weighted FSE and STIR sequences. The signal characteristics and areas of fibrous cap, lipid core, calcification, fibrous tissue, and healthy vessel wall were recorded on MR images and compared with histology. Fibrous cap thickness and maximum wall thickness were also quantified. The percentage of areas of the main plaque components, the ratio of fibrous cap thickness to maximum wall thickness, and plaque burden were calculated and compared. RESULTS: The signal intensity of the lipid core was significantly lower than that of the fibrous cap on T2-weighted, proton-density, and STIR sequences (P < .01) and was comparable on T1-weighted sequences (P = 1.00). Optimal contrast between the lipid core and fibrous cap was found on T2-weighted images. Plaque component mean percentages were comparable between MR imaging and histology: fibrous component (81.86% ± 10.59% versus 81.87% ± 11.59%, P = .999), lipid core (19.51% ± 10.76% versus 19.86% ± 11.56%, P = .863), and fibrous cap (31.10% ± 11.28% versus 30.83% ± 8.51%, P = .463). However, MR imaging overestimated mean calcification (9.68% ± 5.21% versus 8.83% ± 5.67%, P = .030) and plaque burden (65.18% ± 9.01% versus 52.71% ± 14.58%, P < .001). CONCLUSIONS: Ex vivo 3T MR imaging can accurately identify and quantitatively assess intracranial atherosclerotic plaque components, providing a direct reference for in vivo intracranial plaque imaging.

Chorea in the older adult: a full blooded answer.

Chorea is a severe, distressing, movement disorder characterised by excessive, purposeless movements of the limbs, head and orofacial muscles in a generalised and irregularly-timed fashion. In young patients, neurodegenerative (Huntington's disease) and metabolic (Wilson's disease) aetiologies are most common. In the older population, the differential widens to include genetic, structural, metabolic and pharmacological causes. We present a case of an older man who developed progressive choreoathetosis secondary to polycythaemia vera which resolved with serial venesections. The treatment of his underlying condition is discussed.

Rare case of a radiographically occult sacral lesion detected on MRI presenting with intractable back pain.

We report the imaging findings and histopathology of a rare case of sacral hibernoma in a female presenting with right buttock pain while sitting. The lesion was occult on radiographs and CT scan. A small, rounded right S2 lesion was hypointense on T 1 weighted images and hyperintense on short tau inversion-recovery images. It demonstrated homogeneous contrast enhancement. The lesion was biopsied, and histopathology revealed an intraosseous hibernoma composed of brown fat cells. Intraosseous hibernomas are rare and demonstrate non-specific imaging findings requiring biopsy for diagnosis, although most hibernomas are incidental and asymptomatic. Initial treatment with microwave ablation and cementoplasty improved the patient's symptoms temporarily but cementoplasty caused radicular symptoms, and eventually, cement removal, bone curettage, grafting and sacral nerve root decompression were required for symptom remission.

Neuroimaging of rapidly progressive dementias, part 1: neurodegenerative etiologies.

Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, prompt identification and assessment of acute and subacute forms of dementia are critical to effective treatment. Numerous other entities within this category of presenile rapid-onset dementias are untreatable such as the prion-related diseases. Neuroimaging aids in the diagnosis and evaluation of many of these rapidly progressive dementias, which include myriad conditions ranging from variations of more common neurodegenerative dementias, such as Alzheimer disease, dementia with Lewy bodies, and frontotemporal dementia; infectious-related dementias such as acquired immune deficiency syndrome dementia; autoimmune and malignancy-related conditions; to toxic and metabolic forms of encephalopathy. This first of a 2-part review will specifically address the ability of MR imaging and ancillary neuroimaging strategies to support the diagnostic evaluation of rapidly progressive dementias due to neurodegenerative causes.

Genetics of Alzheimer disease.

Alzheimer disease prevails as a major cause of disability in the elderly population and ranks as the most common form of dementia that affects 1 of 8 individuals older than 65 years of age. Most AD cases are late in onset and are probably influenced by both genetic and environmental factors. Apart from age, the risk factors include family history; brain injury, both traumatic and vascular; and metabolic diseases, such as diabetes, hypercholesterolemia, and obesity. Based on twin studies, inheritance plays a role in approximately 80% of cases (familial and sporadic).

Neuroimaging of rapidly progressive dementias, part 2: prion, inflammatory, neoplastic, and other etiologies.

Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, accurate identification and assessment of acute and subacute forms of dementia are critical to effective treatment; neuroimaging aids greatly in narrowing the diagnosis of these conditions. This second installment of a 2-part review of rapidly progressive dementias examines the use of imaging in an assortment of other etiologies in the differential diagnosis, from prion disease and neoplastic-related conditions to rare metabolic and other conditions such as Wernicke encephalopathy. In these clinical conditions, MR imaging has the potential to narrow this broad differential diagnosis and, at times, can definitively aid in the diagnosis of certain conditions on the basis of typical imaging patterns.

MR imaging of papilledema and visual pathways: effects of increased intracranial pressure and pathophysiologic mechanisms.

Papilledema, defined as swelling of the optic disc, frequently occurs in the setting of increased ICP and in a variety of medical conditions, including pseudotumor cerebri, sinus thrombosis, intracerebral hemorrhage, frontal lobe neoplasms, and Chiari malformation. Noninvasive imaging of the ON is possible by using MR imaging, with a variety of findings occurring in the setting of papilledema, including flattening of the posterior sclera, protrusion of the optic disc, widening of the ONS, and tortuosity of the ON. Early recognition of papilledema and elevated ICP is of paramount importance for ensuring restoration of vision. Newer advanced MR imaging techniques such as fMRI and DTI may prove useful in the future to assess the potential effects of papilledema on retinal and visual pathway integrity.

GABA-based evaluation of neurologic conditions: MR spectroscopy.

SUMMARY: GABA serves as a major neurotransmitter of the brain and functions mainly to inhibit neural excitatory activity. Disruption of the GABAergic processes appears to occur in various neurologic and psychiatric conditions, including epilepsy, mood disorders, motor disorders such as focal dystonia and stiff-person syndrome, sleep disorders, neuroplasticity, and drug and alcohol dependence. These concentration differences may be ascertained by using MR spectroscopy to provide information on the concentration of different metabolites. This review briefly discusses advances in MR spectroscopy methods and explores the application of this technique to detect changes in GABA due to disease processes and medication-induced effects.

MR angiography and imaging for the evaluation of middle cerebral artery atherosclerotic disease.

Intracranial atherosclerotic disease may constitute the most common cause of ischemic stroke worldwide; yet, in the developed world, imaging research has largely focused on extracranial atherosclerosis. Many studies in populations of Asian, African, and Hispanic descent demonstrate the preponderance of intracranial stenosis compared with carotid stenosis. This review examines the clinical presentations of MCA atherosclerosis and stenosis and the use of noninvasive MR imaging in the assessment of intracranial vasculature. MRA is a well-validated technique that offers great advantage over traditional angiography. Advances in high-resolution MR imaging of MCA stenosis have the potential to yield excellent visualization of plaque. Future developments in high-resolution MR imaging to depict intracranial atherosclerosis are explored in this review; these advances will guide endovascular therapy and the comparison of novel interventions.

Pseudotumor cerebri: brief review of clinical syndrome and imaging findings.

PTC is a clinical entity of uncertain etiology characterized by intracranial hypertension. The syndrome classically manifests with headaches and visual changes in women with obesity. Traditionally, imaging ruled out secondary causes of elevated CSF pressure but now may reveal findings frequently seen in patients with PTC, including the following: flattening of the globe, an empty sella, an enlarged ONS, protrusion and enhancement of the optic nerve head, and increased tortuosity of the optic nerve. Novel imaging methods, including MR venography, have additionally identified sinovenous stenosis as a potential indicator of PTC.

Examination of indigenous microbiota and survival of Escherichia coli 0157 and Salmonella in a paper milling environment.

AIMS: A public beach was frequently cited for health advisories because of high Escherichia coli levels, the source suspected to be a paper mill located upstream. This investigation sought to confirm whether or not the paper mill was the pollution source, and to characterize the risk to recreational bathers imposed by the source. METHODS AND RESULTS: Quantification of E. coli in river water collected at incremental distances showed that paper mill effluent caused elevated E. coli levels in beach samples. Samples collected throughout the mill were variably positive for heterotrophic bacteria, total coliforms and E. coli, but negative for pathogenic E. coli O157 and Salmonella. Escherichia coli O157 or Salmonella spiked into mill samples (4.2 log(10) or 5.6 log(10) CFU per 100 ml, respectively) fell below detection levels within 14-24 h in raw (unaltered) samples, while in heat-sterilized replicates, the counts remained at initial levels or increased over 36 h. CONCLUSIONS: Pathogenic E. coli O157 and Salmonella were not isolated from paper mill samples. The absence of native bacteria allowed the survival of pathogens, while their presence accelerated pathogen decline. SIGNIFICANCE AND IMPACT OF THE STUDY: The co-existence of paper mill and swimming beach may be reasonable for now in spite of the limitations of an E. coli-based assay for beach water.

Development of a plating medium for selection of Helicobacter pylori from water samples.

The goal of this study was to develop a simple plating medium to allow large-scale screening of water samples for the presence of Helicobacter pylori. Five conventional plating media (brain heart infusion, brucella agar, Columbia blood agar base, campylobacter agar kit Skirrow, and HPSPA medium), each containing a commercial antibiotic supplement, were initially evaluated. Eight strains selected as common waterborne organisms (Acinetobacter, Aeromonas, Bacillus, Escherichia coli, Enterobacter, Enterococcus, Helicobacter pylori, and Pseudomonas strains) were individually plated onto each of these media. Three organisms (Acinetobacter, E. coli, and H. pylori) were able to grow on all five media. This growth was unacceptable since Helicobacter grows very slowly and competing organisms must be inhibited for up to 7 days. Therefore, a more selective medium (HP agar) containing a novel mixture of growth supplements plus amphotericin B and polymyxin B was developed. This medium also included a phenol red color indicator for urease production. Aliquots of nonsterile well water that contained native flora (Flavobacterium, Serratia, Citrobacter, Pasteurella, Ochrobactrum, Rahnella, and unidentified molds) and were further adulterated with the eight strains listed above (10(6) CFU of each strain per 100 ml) were spiked with H. pylori and were plated. In spite of the heavy mixed microbial load, only H. pylori colonies grew during 7 days of incubation at 37 degrees C. The color indicator system allowed presumptive identification of H. pylori colonies sooner (12 to 20 h) than the conventional media tested allowed. The HP formulation developed in this study provides a medium with superior selectivity for H. pylori from mixed microbial populations in water and reduces the time required to complete the assay.

Evaluation of lactic acid bacterium fermentation products and food-grade chemicals to control Listeria monocytogenes in blue crab (Callinectes sapidus) meat.

Fresh blue crab (Callinectes sapidus) meat was obtained from retail markets in Florida and sampled for viable Listeria monocytogenes. The pathogen was found in crabmeat in three of four different lots tested by enrichment and at levels of 75 CFU/g in one of the same four lots by direct plating. Next, crabmeat was steam sterilized, inoculated with a three-strain mixture of L. monocytogenes (ca. 5.5 log10 CFU/g), washed with various lactic acid bacterium fermentation products (2,000 to 20,000 arbitrary units [AU]/ml of wash) or food-grade chemicals (0.25 to 4 M), and stored at 4 degrees C. Counts of the pathogen remained relatively constant in control samples during storage for 6 days, whereas in crabmeat washed with Perlac 1911 or MicroGard (10,000 to 20,000 AU), numbers initially decreased (0.5 to 1.0 log10 unit/g) but recovered to original levels within 6 days. Numbers of L. monocytogenes cells decreased 1.5 to 2.7 log10 units/g of crabmeat within 0.04 day when washed with 10,000 to 20,000 AU of Alta 2341, enterocin 1083, or Nisin per ml. Thereafter, counts increased 0.5 to 1.6 log10 units within 6 days. After washing with food-grade chemicals, modest reductions (0.4 to 0.8 log10 unit/g) were observed with sodium acetate (4 M), sodium diacetate (0.5 or 1 M), sodium lactate (1 M), or sodium nitrite (1.5 M). However, Listeria counts in crabmeat washed with 2 M sodium diacetate decreased 2.6 log10 units/g within 6 days. In addition, trisodium phosphate reduced L. monocytogenes counts from 1.7 (0.25 M) to > 4.6 (1 M) log10 units/g within 6 days.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of diacetate with nitrite, lactate, or pediocin on the viability of Listeria monocytogenes in turkey slurries.

The antilisterial effects of sodium diacetate (0.1, 0.3 and 0.5%) alone or in combination with sodium nitrite (30 ppm), sodium lactate (2.5%) or pediocin (5000 arbitrary units/ml) were evaluated in slurries (25% meat in sterile deionized H2O) prepared from vacuum-packaged, ready-to-eat turkey breast meat and challenged with Listeria monocytogenes. In the absence of food additives, counts of L. monocytogenes increased from 4.5 log10 cfu/ml to ca. 8 log10 cfu/ml within 1 day at 25 degrees C and within 14 days at 4 degrees C. Similarly, the pathogen grew to ca. 8 log10 cfu/ml within 1 d at 25 degrees C and within 28 days at 4 degrees C in slurries containing nitrite or lactate. In the presence of pediocin, after an initial decrease of 0.9 log10 cfu/ml, numbers of the pathogen reached ca. 8 log10 cfu/ml within 5 days at 25 degrees C and within 28 days at 4 degrees C. However, 0.3 and 0.5% diacetate in turkey slurries were listericidal at 4 and 25 degree C, respectively. In the presence of nitrite with diacetate, there was no appreciable difference in growth of L. monocytogenes compared with diacetate alone. Antilisterial activity was potentiated in treatments containing lactate with 0.3% diacetate at 25 degrees C and lactate with 0.1% diacetate at 4 degrees C, compared to similar treatments containing diacetate or lactate alone. A listericidal effect (ca. 7 log10 cfu/ml difference compared to slurries without additives) was observed in treatments containing pediocin with 0.5% diacetate at 25 degrees C and pediocin with 0.3% diacetate at 4 degrees C. The pH of slurries containing 0.3 or 0.5% diacetate was 5.5 and 5.2, respectively, whereas nitrite (pH 6.2), lactate (pH 6.3) or pediocin (pH 6.2) in slurries had a negligible effect on pH compared to the control (pH 6.2). The increased antilisterial activity in slurries with diacetate in combination with other additives was due to synergistic effects and not just pH. Thus, sodium diacetate alone can be used to delay growth of L. monocytogenes in turkey, and an additional level of safety can be achieved using diacetate in combination with sodium lactate or pediocin.

Antilisterial activity of pediocin AcH in model food systems in the presence of an emulsifier or encapsulated within liposomes.

The listericidal activity of pediocin AcH was evaluated in slurries (5, 10, or 25% in dH2O) of nonfat dry milk, butterfat, beef muscle tissue, or beef tallow. Slurries were inoculated with Listeria monocytogenes (2-strain mixture; 2.5 x 10(6) cfu/ml) and then with pediocin AcH (30,000 arbitrary units (AU) per ml of slurry). Although pediocin activity was reduced in slurries, sufficient pediocin remained to decrease the listeriae population. For all slurries tested, the greatest decrease in counts of Listeria (1.2-1.8 log10 cfu decrease) and decrease in pediocin activity (12-54% recovery of original activity) occurred within 1.5 min of addition of pediocin to slurries. Thereafter, counts of Listeria did not change appreciably, but pediocin activity continued to decrease in most treatments for up to 60 min. In general, greater activity was recovered from: (i) slurries of lower (5%) compared to higher (25%) concentrations of food; and (ii) dairy- compared to meat-based slurries. Next, pediocin AcH was encapsulated within phosphatidyl-choline-based liposomes before addition to slurries (10%), or was used unencapsulated in slurries (10%) containing the emulsifier Tween 80. Greater pediocin activity (29-62% increase; average over all concentrations) was recovered from slurries containing encapsulated compared to free pediocin AcH. Likewise, greater pediocin activity was recovered from slurries containing an emulsifier (4-90% increase; average over all concentrations) compared to otherwise similar slurries without Tween 80. The additional recovery of pediocin activity afforded by liposomes or Tween 80 underscores the potential for direct application of biopreservatives to provide another hurdle for L. monocytogenes in foods.