MR-based proton density fat fraction (PDFF) of the vertebral bone marrow differentiates between patients with and without osteoporotic vertebral fractures

The bone marrow proton density fat fraction (PDFF) assessed with MRI enables the differentiation between osteoporotic/osteopenic patients with and without vertebral fractures. Therefore, PDFF may be a potentially useful biomarker for bone fragility assessment.

INTRODUCTION

To evaluate whether magnetic resonance imaging (MRI)-based proton density fat fraction (PDFF) of vertebral bone marrow can differentiate between osteoporotic/osteopenic patients with and without vertebral fractures.

METHODS

Of the 52 study patients, 32 presented with vertebral fractures of the lumbar spine (66.4 ± 14.4 years, 62.5% women; acute low-energy osteoporotic/osteopenic vertebral fractures, N = 25; acute high-energy traumatic vertebral fractures, N = 7). These patients were frequency matched for age and sex to patients without vertebral fractures (N = 20, 69.3 ± 10.1 years, 70.0% women). Trabecular bone mineral density (BMD) values were derived from quantitative computed tomography. Chemical shift encoding-based water-fat MRI of the lumbar spine was performed, and PDFF maps were calculated. Associations between fracture status and PDFF were assessed using multivariable linear regression models.

RESULTS

Over all patients, mean PDFF and trabecular BMD correlated significantly (r =  - 0.51, P < 0.001). In the osteoporotic/osteopenic group, those patients with osteoporotic/osteopenic fractures had a significantly higher PDFF than those without osteoporotic fractures after adjusting for age, sex, weight, height, and trabecular BMD (adjusted mean difference [95% confidence interval], 20.8% [10.4%, 30.7%]; P < 0.001), although trabecular BMD values showed no significant difference between the subgroups (P = 0.63). For the differentiation of patients with and without vertebral fractures in the osteoporotic/osteopenic subgroup using mean PDFF, an area under the receiver operating characteristic (ROC) curve (AUC) of 0.88 (P = 0.006) was assessed. When evaluating all patients with vertebral fractures, those with high-energy traumatic fractures had a significantly lower PDFF than those with low-energy osteoporotic/osteopenic vertebral fractures (P < 0.001).

CONCLUSION

MR-based PDFF enables the differentiation between osteoporotic/osteopenic patients with and without vertebral fractures, suggesting the use of PDFF as a potential biomarker for bone fragility.

Hyperintense Vessels on FLAIR: Hemodynamic Correlates and Response to Thrombolysis

BACKGROUND AND PURPOSE

Hyperintense vessels on baseline FLAIR MR imaging of patients with ischemic stroke have been linked to leptomeningeal collateralization, yet the ability of these to maintain viable ischemic tissue remains unclear. We investigated whether hyperintense vessels on FLAIR are associated with the severity of hypoperfusion and response to thrombolysis in patients treated with intravenous tissue-plasminogen activator.

MATERIALS AND METHODS

Consecutive patients with ischemic stroke with an MR imaging before and within 24 hours of treatment, with proved vessel occlusion and available time-to-maximum maps were included (n = 62). The severity of hypoperfusion was characterized on the basis of the hypoperfusion intensity ratio (volume with severe/mild hypoperfusion [time-to-maximum ≥ 8 seconds / time-to-maximum ≥ 2 seconds]). The hypoperfusion intensity ratio was dichotomized at the median to differentiate moderate (hypoperfusion intensity ratio ≤ 0.447) and severe (hypoperfusion intensity ratio > 0.447) hypoperfusion. Good outcome was defined as a modified Rankin Scale score of ≤2.

RESULTS

Hyperintense vessels on FLAIR were identified in 54 patients (87%). Patients with extensive hyperintense vessels on FLAIR (>4 sections) had higher NIHSS scores, larger baseline lesion volumes, higher rates of perfusion-diffusion mismatch, and more severe hypoperfusion (hypoperfusion intensity ratio). In stepwise backward multivariate regression analysis for the dichotomized hypoperfusion intensity ratio (including stroke etiology, age, perfusion deficit, baseline lesion volume, smoking, and extent of hyperintense vessels on FLAIR), extensive hyperintense vessels on FLAIR were independently associated with severe hypoperfusion (OR, 6.8; 95% CI, 1.1-42.7; P = .04). The hypoperfusion intensity ratio was an independent predictor of a worse functional outcome at 3 months poststroke (OR, 0.2; 95% CI, 0.5-0.6; P < .01).

CONCLUSIONS

Hyperintense vessels on FLAIR are associated with larger perfusion deficits, larger infarct growth, and more severe hypoperfusion, suggesting that hyperintense vessels on FLAIR most likely indicate severe ischemia as a result of insufficient collateralization.

MRI-based intravenous thrombolysis in stroke patients with unknown time of symptom onset

BACKGROUND

Currently, stroke patients with unknown time of symptom onset (UTOS) are excluded from therapy with intravenous tissue Plasminogen Activator. We hypothesized that MRI-based intravenous thrombolysis is safe in UTOS.

METHODS

We analyzed radiological and clinical data as well as outcomes of stroke patients (including UTOS) who received intravenous thrombolytic therapy after MRI.

RESULTS

Compared to patients with known time of symptom onset (n=131), UTOS (n=17) were older (81, 71-88 vs. 75 years, 66-82, P=0.03), had a longer median time between last-seen-well and thrombolysis (12.3 h, IQR 11.5-15.2 h vs. 2.1 h, 1.8-2.8 h, P<0.01), had a longer median door-to-needle time (86 min, 49-112 vs. 60 min, 49-76, P=0.02), and a higher rate of arterial obstruction on MR-angiography (82.4% vs. 56.5%, P=0.04). No symptomatic intracerebral hemorrhage occurred in UTOS. After 3 months, there was no significant difference between groups concerning good functional outcome (modified Rankin Scale 0-2; 35.3% vs. 49.6%, P=0.26) or mortality (0% vs. 15.3%, P=0.08). In multivariate analyses including age, gender, baseline NIHSS, and atrial fibrillation UTOS did not have an independent effect on good functional outcome after 3 months (OR 1.16; 0.32-4.12, P=0.81).

CONCLUSIONS

Thrombolysis after MRI seems safe and effective in UTOS. This observation may encourage those who plan prospective placebo-controlled trials of thrombolytics in this subgroup of stroke patients.

[Cultivated epidermis as a skin replacement--improved technics using mesh silastic sheets]

The cover of cutaneous wounds with cultured epidermis can be significantly improved by prior backing of the epithelium with meshed silastic sheets, whereas other materials, such as vaseline gauze, foam rubber etc., are not as satisfactory. Meshed silastic is affixed to the epithelium surface just before the enzymatic detachment from the culture flask is completed. Thus it protects the delicate epithelial membrane from injury during transplantation and helps to control its polar orientation. In addition, the silastic mesh prevents the graft, which initially does not possess any horny layer, from drying up and allows adequate drainage of wound secretions. Cultured epidermal grafts prepared by this method take very well (more than 90%) attaching to the wound bed quite firmly within a week.

[Allergic granulomatosis (Churg-Strauss syndrome)]

Allergic granulomatosis is a rare life-threatening systemic disorder of unknown origin, which represents a variant of systemic necrotizing vasculitis affecting medium-sized arteries and venules. Histologically, allergic granulomatosis is characterized by vascular and extravascular necrotizing palisading granulomas with prominent eosinophilia (Churg-Strauss granulomas). The clinical criteria include atopy with severe allergic asthma, pronounced peripheral eosinophilia, and nodular infiltrates of the skin and internal organs (Churg-Strauss granulomas). The internal organs most commonly involved are the lungs, gastrointestinal tract and, less often, the peripheral nerves, heart, and kidneys. Associated symptoms include fever, arthralgias and skin rashes, such as erythema multiforme, necrotizing venolitis, fixed drug eruption, and urticaria. Allergic granulomatosis shares common features with Wegener's granulomatosis and polyarteritis nodosa and may be related to the latter condition; overlap syndromes are a well-known occurrence. Similar to the other manifestations of systemic necrotizing vasculitis, immune complexes have been detected in fresh lesions and are suspected of being the basic pathogenetic findings. The causative antigens are likely to be respiratory antigens. The prognosis of untreated allergic granulomatosis is poor (mortality of approximately 50% within the first year). Systemic corticosteroids and cyclophosphamide are effective; complete remissions following cyclophosphamide treatment have been reported.

[Acute implantation technique of the ellipsoid heart for clinical left ventricular assistance (author's transl)]

The results of the first clinical trials of left ventricular assist devices are not encouraging. The only indication at present is in patients with cardiac failure after cardiac operations. The acute type of ellipsoid heart described in this paper-displays a canulation technique where the inflow canula inserted in the left ventricular cavity via the left atrium and the outflow canula is directly connected to the aortic canula of the cardiopulmonary bypass. The haemodynamic response shows the efficacy of this system. The circulation can be maintained in severe cardiac failure, as well as in ventricular fibrillation and cardiac arrest. On the basis of data obtained in experiments on 7 female calves this system is considered worthy of clinical trial.