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81.
82.
Romhild M. Hoogeveen Chris J. G. Bakker Max A. Viergever 《Journal of magnetic resonance imaging : JMRI》1997,7(2):321-330
A problem of current MRA techniques is the inability to accurately depict the vascular anatomy, particularly in areas of disturbed flow. Various reasons, such as intravoxel phase dispersion, saturation, temporal variations, and maximum intensity projection (MIP) nonlinearity, cause a wrong delineation of vessel boundaries. A phase contrast (PC)-based postprocessing operation, the phase derivative (PhD), is introduced to detect phase fluctuations indicating flow. Two-dimensional and three-dimensional angiographic reconstruction algorithms are presented. Mathematical formulas are derived to predict the effect of sampling to flow profiles and the effect on the PhD of these profiles. Numerical, phantom, and preliminary in vivo experiments demonstrate that PhD images do not suffer from phase wraps and allow a velocity dynamic range extension only limited by a differential phase change. It is also shown that PhD MIPs produce higher signal-to-noise ratios than conventional PC angiograms and give a better impression of the anatomy of (stenotic) vessels and of their diameters for both laminar and disturbed flow. 相似文献
83.
Thirteen cases are reported with normal levels of prostate-specific antigen and elevated prostatic acid phosphatase (PAP). Conditions that were associated with an elevated PAP were myeloproliferative syndromes (four cases), metastatic nonprostatic carcinoma (six cases), prostatic carcinoma (one case), tuberculosis with a concurrent lupus-like syndrome (one case), and osteomyelitis (one case). The inclusion of PAP in the initial investigation of cases with suspected prostatic disease results in a decreased specificity. 相似文献
84.
Norbert Boos Daniel Dreier Esther Hilfiker Volker Schade Roland Kreis Josef Hora Max Aebi Chris Boesch 《Journal of orthopaedic research》1997,15(1):141-149
The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T1 and T2 relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T1 and T2, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T1 and T2 relaxation times. Symptomatic disc herniations exhibited significantly (pT1 < 0.04 and pT2 < 0.003) shorter T1(ΔT1:–182.1 milliseconds, ?15%) and T2(ΔT2: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition. 相似文献
85.
Rosendo A Rodriguez MD PhD Garry Cornel FRCS Lloyd Semelhago MD William M Splinter MD Nihal A Weerasena FRCS 《The Annals of thoracic surgery》1997,64(6):1820-1822
A pediatric cardiac case of transient obstruction of the superior vena cava by the venous cannula before cardiopulmonary bypass is presented. With venous obstruction and increase in central venous pressure, reduced cerebral blood flow velocities and absence of diastolic Doppler flow were detected. This was followed by regional cerebral venous oxygen desaturation and global electroencephalographic slowing. Reposition of the venous cannula led to the recovery of these physiologic indicators and a noncomplicated clinical outcome. 相似文献
86.
87.
Pancreatitis after parathyroidectomy 总被引:1,自引:0,他引:1
N J London D M Lloyd H Pearson J P Neoptolemos P R Bell 《The British journal of surgery》1986,73(9):766-767
88.
89.
Philip F. Halloran Joan Urmson Vido Ramassar Anette Melk Lin-Fu Zhu Brendan P. Halloran R. Chris Bleackley 《American journal of transplantation》2004,4(5):705-712
Organ allograft rejection is strongly associated with the presence of alloreactive cytotoxic T cells but the role of cytotoxicity in the pathologic lesions is unclear. Previous studies showed that the principal lesions of kidney rejection - interstitial infiltration, tubulitis, and endothelial arteritis - are T-cell-dependent and antibody-independent. We studied the role of cytotoxic granule components perforin and granzymes A and B in the evolution of the T-cell-mediated lesions of mouse kidney transplant rejection. By real-time RT-PCR, allografts rejecting in wild-type hosts at days 5, 7, 21, and 42 showed massively elevated and persistent expression of perforin and granzymes A and B, but evolution of tubulitis and arteritis did not correlate with increasing granzyme or perforin expression. Allografts transplanted into hosts with disrupted genes for perforin or granzymes A and B showed no change in tubulitis, arteritis, or MHC induction. Thus the development of the histologic lesions diagnostic of T-cell-mediated kidney transplant rejection are associated with but not mediated by perforin or granzyme A or B. Together with previous graft survival studies, these results indicate that the granule-associated cytotoxic mechanisms of T cells are not the effectors of T-cell-mediated allograft rejection. 相似文献
90.