Multislice CT for assessing in-stent dimensions after left main coronary artery stenting: a comparison with three dimensional intravascular ultrasound

Objective: To evaluate the agreement between multislice CT (MSCT) and intravascular ultrasound (IVUS) to assess the in-stent lumen diameters and lumen areas of left main coronary artery (LMCA) stents. Design: Prospective, observational single centre study. Setting: A single tertiary referral centre. Patients: Consecutive patients with LMCA stenting excluding patients with atrial fibrillation and chronic renal failure. Interventions: MSCT and IVUS imaging at 912 months follow-up were performed for all patients. Main outcome measures: Agreement between MSCT and IVUS minimum luminal area (MLA) and minimum luminal diameter (MLD). A receiver operating characteristic (ROC) curve was plotted to find the MSCT cut-off point to diagnose binary restenosis equivalent to 6 mm2 by IVUS. Results: 52 patients were analysed. PassingBablok regression analysis obtained a β coefficient of 0.786 (0.586 to 1.071) for MLA and 1.250 (0.936 to 1.667) for MLD, ruling out proportional bias. The α coefficient was −3.588 (−8.686 to −0.178) for MLA and −1.713 (−3.583 to −0.257) for MLD, indicating an underestimation trend of MSCT. The ROC curve identified an MLA ≤4.7 mm2 as the best threshold to assess in-stent restenosis by MSCT. Conclusions: Agreement between MSCT and IVUS to assess in-stent MLA and MLD for LMCA stenting is good. An MLA of 4.7 mm2 by MSCT is the best threshold to assess binary restenosis. MSCT imaging can be considered in selected patients to assess LMCA in-stent restenosis

Volume-targeted and whole-heart coronary magnetic resonance angiography using an intravascular contrast agent.

PURPOSE: To compare volume-targeted and whole-heart coronary magnetic resonance angiography (MRA) after the administration of an intravascular contrast agent. MATERIALS AND METHODS: Six healthy adult subjects underwent a navigator-gated and -corrected (NAV) free breathing volume-targeted cardiac-triggered inversion recovery (IR) 3D steady-state free precession (SSFP) coronary MRA sequence (t-CMRA) (spatial resolution = 1 x 1 x 3 mm(3)) and high spatial resolution IR 3D SSFP whole-heart coronary MRA (WH-CMRA) (spatial resolution = 1 x 1 x 2 mm(3)) after the administration of an intravascular contrast agent B-22956. Subjective and objective image quality parameters including maximal visible vessel length, vessel sharpness, and visibility of coronary side branches were evaluated for both t-CMRA and WH-CMRA. RESULTS: No significant differences (P = NS) in image quality were observed between contrast-enhanced t-CMRA and WH-CMRA. However, using an intravascular contrast agent, significantly longer vessel segments were measured on WH-CMRA vs. t-CMRA (right coronary artery [RCA] 13.5 +/- 0.7 cm vs. 12.5 +/- 0.2 cm; P < 0.05; and left circumflex coronary artery [LCX] 11.9 +/- 2.2 cm vs. 6.9 +/- 2.4 cm; P < 0.05). Significantly more side branches (13.3 +/- 1.2 vs. 8.7 +/- 1.2; P < 0.05) were visible for the left anterior descending coronary artery (LAD) on WH-CMRA vs. t-CMRA. Scanning time and navigator efficiency were similar for both techniques (t-CMRA: 6.05 min; 49% vs. WH-CMRA: 5.51 min; 54%, both P = NS). CONCLUSION: Both WH-CMRA and t-CMRA using SSFP are useful techniques for coronary MRA after the injection of an intravascular blood-pool agent. However, the vessel conspicuity for high spatial resolution WH-CMRA is not inferior to t-CMRA, while visible vessel length and the number of visible smaller-diameter vessels and side-branches are improved.

Improved three-dimensional free-breathing coronary magnetic resonance angiography using gadocoletic acid (B-22956) for intravascular contrast enhancement.

PURPOSE: To evaluate gadocoletic acid (B-22956), a gadolinium-based paramagnetic blood pool agent, for contrast-enhanced coronary magnetic resonance angiography (MRA) in a Phase I clinical trial, and to compare the findings with those obtained using a standard noncontrast T2 preparation sequence. MATERIALS AND METHODS: The left coronary system was imaged in 12 healthy volunteers before B-22956 application and 5 (N = 11) and 45 (N = 7) minutes after application of 0.075 mmol/kg of body weight (BW) of B-22956. Additionally, imaging of the right coronary system was performed 23 minutes after B-22956 application (N = 6). A three-dimensional gradient echo sequence with T2 preparation (precontrast) or inversion recovery (IR) pulse (postcontrast) with real-time navigator correction was used. Assessment of the left and right coronary systems was performed qualitatively (a 4-point visual score for image quality) and quantitatively in terms of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, visible vessel length, maximal luminal diameter, and the number of visible side branches. RESULTS: Significant (P < 0.01) increases in SNR (+42%) and CNR (+86%) were noted five minutes after B-22956 application, compared to precontrast T2 preparation values. A significant increase in CNR (+40%, P < 0.05) was also noted 45 minutes postcontrast. Vessels (left anterior descending artery (LAD), left coronary circumflex (LCx), and right coronary artery (RCA)) were also significantly (P < 0.05) sharper on postcontrast images. Significant increases in vessel length were noted for the LAD (P < 0.05) and LCx and RCA (both P < 0.01), while significantly more side branches were noted for the LAD and RCA (both P < 0.05) when compared to precontrast T2 preparation values. CONCLUSION: The use of the intravascular contrast agent B-22956 substantially improves both objective and subjective parameters of image quality on high-resolution three-dimensional coronary MRA. The increase in SNR, CNR, and vessel sharpness minimizes current limitations of coronary artery visualization with high-resolution coronary MRA.

Relation between plaque type, plaque thickness, blood shear stress, and plaque stress in coronary arteries assessed by X-ray Angiography and Intravascular Ultrasound

Purpose: Atheromatic plaque progression is affected, among others phenomena, by biomechanical, biochemical, and physiological factors. In this paper, the authors introduce a novel framework able to provide both morphological (vessel radius, plaque thickness, and type) and biomechanical (wall shear stress and Von Mises stress) indices of coronary arteries. Methods: First, the approach reconstructs the three-dimensional morphology of the vessel from intravascular ultrasound(IVUS) and Angiographic sequences, requiring minimal user interaction. Then, a computational pipeline allows to automatically assess fluid-dynamic and mechanical indices. Ten coronary arteries are analyzed illustrating the capabilities of the tool and confirming previous technical and clinical observations. Results: The relations between the arterial indices obtained by IVUS measurement and simulations have been quantitatively analyzed along the whole surface of the artery, extending the analysis of the coronary arteries shown in previous state of the art studies. Additionally, for the first time in the literature, the framework allows the computation of the membrane stresses using a simplified mechanical model of the arterial wall. Conclusions: Circumferentially (within a given frame), statistical analysis shows an inverse relation between the wall shear stress and the plaque thickness. At the global level (comparing a frame within the entire vessel), it is observed that heavy plaque accumulations are in general calcified and are located in the areas of the vessel having high wall shear stress. Finally, in their experiments the inverse proportionality between fluid and structural stresses is observed.

Multislice CT for assessing in-stent dimensions after left main coronary artery stenting: a comparison with three dimensional intravascular ultrasound

Objective: To evaluate the agreement between multislice CT (MSCT) and intravascular ultrasound (IVUS) to assess the in-stent lumen diameters and lumen areas of left main coronary artery (LMCA) stents. Design: Prospective, observational single centre study. Setting: A single tertiary referral centre. Patients: Consecutive patients with LMCA stenting excluding patients with atrial fibrillation and chronic renal failure. Interventions: MSCT and IVUS imaging at 9-12 months follow-up were performed for all patients. Main outcome measures: Agreement between MSCT and IVUS minimum luminal area (MLA) and minimum luminal diameter (MLD). A receiver operating characteristic (ROC) curve was plotted to find the MSCT cut-off point to diagnose binary restenosis equivalent to 6 mm2 by IVUS. Results: 52 patients were analysed. Passing-Bablok regression analysis obtained a β coefficient of 0.786 (0.586 to 1.071) for MLA and 1.250 (0.936 to 1.667) for MLD, ruling out proportional bias. The α coefficient was −3.588 (−8.686 to −0.178) for MLA and −1.713 (−3.583 to −0.257) for MLD, indicating an underestimation trend of MSCT. The ROC curve identified an MLA ≤4.7 mm2 as the best threshold to assess in-stent restenosis by MSCT. Conclusions: Agreement between MSCT and IVUS to assess in-stent MLA and MLD for LMCA stenting is good. An MLA of 4.7 mm2 by MSCT is the best threshold to assess binary restenosis. MSCT imaging can be considered in selected patients to assess LMCA in-stent restenosis

Relation between plaque type, plaque thickness, blood shear stress, and plaque stress in coronary arteries assessed by X-ray Angiography and Intravascular Ultrasound

Purpose: Atheromatic plaque progression is affected, among others phenomena, by biomechanical, biochemical, and physiological factors. In this paper, the authors introduce a novel framework able to provide both morphological (vessel radius, plaque thickness, and type) and biomechanical (wall shear stress and Von Mises stress) indices of coronary arteries. Methods: First, the approach reconstructs the three-dimensional morphology of the vessel from intravascular ultrasound(IVUS) and Angiographic sequences, requiring minimal user interaction. Then, a computational pipeline allows to automatically assess fluid-dynamic and mechanical indices. Ten coronary arteries are analyzed illustrating the capabilities of the tool and confirming previous technical and clinical observations. Results: The relations between the arterial indices obtained by IVUS measurement and simulations have been quantitatively analyzed along the whole surface of the artery, extending the analysis of the coronary arteries shown in previous state of the art studies. Additionally, for the first time in the literature, the framework allows the computation of the membrane stresses using a simplified mechanical model of the arterial wall. Conclusions: Circumferentially (within a given frame), statistical analysis shows an inverse relation between the wall shear stress and the plaque thickness. At the global level (comparing a frame within the entire vessel), it is observed that heavy plaque accumulations are in general calcified and are located in the areas of the vessel having high wall shear stress. Finally, in their experiments the inverse proportionality between fluid and structural stresses is observed.

A ecografia no diagnóstico das lesões músculo-tendinosas do ombro

Este estudo propôs-se a revisar os aspectos relevantes da anatomia, técnica de exame e achados de imagens, com o objetivo de auxiliar o radiologista no diagnóstico diferencial frente às afecções músculo-tendinosas do ombro. Foram realizadas 34 ultra-sonografias da região do ombro, no período de janeiro a dezembro de 2001. A avaliação foi realizada com transdutores de alta freqüência (7,5-10 MHz). O exame foi normal em 23% dos pacientes (oito casos). Dos 26 casos alterados, observaram-se oito com ruptura total (30%), cinco com ruptura parcial (19%), dez com tendinopatia (38%), um com tendinopatia calcificada (3%), um com tenossinovite bicipital (3%) e um com tendinopatia associada a artrite gotosa (3%). A falta de experiência e de conhecimento das principais alterações que acometem o ombro é um dos principais pontos limitantes do diagnóstico ultra-sonográfico das lesões do ombro. Portanto, o estudo dessas alterações deve ser realizado amplamente.

Radial dose function of a 90Sr 90Y seed in water and A150: Comment on Calibration and characterization of beta-particle sources for intravascular brachytherapy

Intravascular brachytherapy with beta sources has become a useful technique to prevent restenosis after cardiovascular intervention. In particular, the Beta-Cath high-dose-rate system, manufactured by Novoste Corporation, is a commercially available 90Sr 90Y source for intravascular brachytherapy that is achieving widespread use. Its dosimetric characterization has attracted considerable attention in recent years. Unfortunately, the short ranges of the emitted beta particles and the associated large dose gradients make experimental measurements particularly difficult. This circumstance has motivated the appearance of a number of papers addressing the characterization of this source by means of Monte Carlo simulation techniques.

Quantificação volumétrica da hiperplasia neointimal em artérias ilíacas após implante de suporte intravascular metálico

OBJETIVO: Quantificar a hiperplasia neointimal em artérias ilíacas após stent, correlacionando fatores clínicos, arteriais e materiais dos stents. MATERIAIS E MÉTODOS: De junho de 2003 a agosto de 2005, 60 pacientes realizaram angioplastia transluminal percutânea e stent. Desses, 30 foram reestudados com ultrassonografia intravascular. Os dados foram analisados no laboratório de análise quantitativa. RESULTA-DOS: Dezesseis pacientes eram do sexo masculino (53,3%) e 14 (46,7%), do sexo feminino. A média de idade foi de 60,3 anos. Apresentaram hipertensão arterial 22 pacientes (73,3%), tabagismo, 18 (62,1%), hiperlipidemia, 20 (66,7%), e diabetes, 9 (30%). Foram implantados 20 stents de nitinol (66,7%) e 10 de aço inoxidável (33,3%). Quatro pacientes eram TASC A (13,3%), 15 eram TASC B (50%) e 11, TASC C (36,7%). O volume da hiperplasia variou de 49,02 mm³ a 112,87 mm³ (média de 80,33 mm³). O percentual de obstrução intra-stent variou de 18% a 47% (média de 27,4%). Os resultados clínicos obtidos com stent se mantiveram até o reestudo. CONCLUSÃO: A hiperplasia neointimal sempre ocorre após a angioplastia transluminal percutânea e stent, porém os percentuais de obstrução não foram superiores a 50% em nenhum caso. Não houve diferença estatisticamente significante dos percentuais de obstrução intra-stent quanto aos materiais dos stents, aos fatores clínicos e aos fatores arteriais.

Avaliação de índices dopplerfluxométricos da veia cava inferior e do ducto venoso em fetos submetidos à transfusão intravascular

OBJETIVO: avaliar os efeitos da transfusão intravascular nos índices dopplerfluxométricos do ducto venoso e da veia cava inferior (SV/CA) e relacionar essas alterações com o nível de hemoglobina pré-transfusão intravascular. MÉTODOS: trata-se de estudo transversal prospectivo. Foram realizadas 62 transfusões intravasculares em 27 fetos de gestações complicadas por isoimunização materno-fetal. Os 62 casos foram divididos em dois grupos: (A) fetos com níveis de hemoglobina pré-transfusão £10 g/dL, (B) fetos com níveis de hemoglobina pré-transfusão >10 g/dL. Os índices SV/CA e CA/SV foram medidos usando Doppler colorido 6 horas antes e 12 horas após a transfusão. Compararam-se os valores dos índices antes e após as transfusões em todos os 62 casos, e após a transfusão em cada grupo. O teste de Wilcoxon foi usado para comparação. Os resultados foram considerados estatisticamente significativos quando p<0,05. RESULTADOS: quando estudamos todo o grupo (62 casos), não encontramos diferença significativa no índice CA/SV antes e após a transfusão (p=0,775). No entanto, o índice SV/CA apresentou aumento significativo após a transfusão (p=0,004). Nos fetos com níveis de hemoglobina pré-transfusão £10 g/dL não foi observada diferença significativa nos valores de ambos os índices SV/CA e CA/SV, com p=0,061 e p=0,345, respectivamente. Após a transfusão intravascular houve aumento significativo do índice CA/SV em fetos com níveis de hemoglobina pré-transfusão >10 g/dL (p=0,049), mas o índice SV/CA não se alterou nesse grupo (p=0,086). CONCLUSÕES: o estudo por dopplervelocimetria venosa pode ser útil para a compreensão dos ajustes hemodinâmicos fetais após a transfusão intravascular. O aumento no índice SV/CA sem alteração no índice CA/SV após a transfusão em fetos anêmicos pode ser mecanismo compensatório importante em resposta ao aumento do volume intravascular. O aumento do índice CA/SV em fetos com hemoglobina pré-transfusão <10 g/dL sugere um estado de hipervolemia fetal.

Avaliação dos parâmetros de imagens de massas anexiais pélvicas em tele-ecografia

OBJETIVO: Avaliar os parâmetros ultrassonográficos relacionados às características morfológicas de massas anexiais pélvicas por meio da obtenção de imagens bidimensionais por um observador presencial, encaminhadas eletronicamente (via tele-ecografia) nos modos estático e dinâmico a observadores não presenciais (à distância) para análises comparativas inter e intraobservadores a fim da validação de uma segunda opinião. MÉTODOS: No período de março a agosto de 2010 foram selecionadas 50 pacientes que apresentavam visualização de massa anexial pélvica no exame ecográfico. Elas foram submetidas ao exame ultrassonográfico por vias abdominal e endovaginal. As imagens foram capturadas nos modos estático e dinâmico, encaminhadas eletronicamente para avaliação de dois examinadores não presenciais e avaliadas de acordo com parâmetros morfológicos ultrassonográficos previamente determinados. RESULTADOS: Os avaliadores não presenciais nas modalidades estática e dinâmica obtiveram concordância quase perfeita para todos os parâmetros morfológicos com valores de Kappa entre 0,6 e 0,8. Não houve diferença entre as modalidades empregadas, exceto para o parâmetro morfológico projeção papilar na modalidade estática, em que a concordância foi quase perfeita (0,8) enquanto na modalidade dinâmica foi substancial (0,6). CONCLUSÕES: Os parâmetros ultrassonográficos das características de massas anexiais pélvicas encaminhadas por tele-ecografia são passíveis de serem validadas para emissão de uma segunda opinião. Não houve diferenças significativas quanto à metodologia empregada na emissão das imagens tele-ecográficas (estática ou dinâmica) na caracterização da composição das massas anexiais pélvicas.

Avaliação da artéria subclávia direita na ecografia do primeiro trimestre

OBJETIVO: Avaliar a artéria subclávia direita durante a ecografia do primeiro trimestre, descrever a técnica para a sua avaliação e, em caso de identificação de artéria subclávia direita aberrante (ARSA), determinar sua associação com alterações cromossómicas e/ou malformações cardíacas e sua orientação. MÉTODOS: Estudo prospectivo que consistiu na avaliação da artéria subclávia direita no primeiro trimestre (comprimento crânio caudal entre 45 e 84 milímetros), em todas as gestações únicas, consecutivas, por um único examinador, ecógrafo Voluson E8 (GE Healthcare, Zipf, Áustria) com sonda transabdominal RAB 4-8-D, 2 a 8 MHz, por um período não superior a 2 minutos, numa população geral de baixo risco. Com a ajuda do power/color Doppler, a artéria subclávia direita foi classificada como normal ou aberrante. Foi utilizada análise de regressão estatística (IBM SPSS Statistics for Windows, versão 20.0) para estudar o grau de associação entre a falha na avaliação/classificação da artéria subclávia direita e o comprimento crânio-caudal fetal e o índice de massa corporal materno. RESULTADOS: A mediana da idade materna foi de 30 anos (variando entre 17 e 43 anos) e a mediana do tempo de gestação no momento da avaliação da artéria subclávia direita foi de 12 semanas de gestação (variando entre 11 e 13 semanas de gestação). A avaliação da artéria subclávia direita foi possível em 138/176 (78,4%) dos casos. ARSA foi diagnosticada em um único caso (0,7%). Esse feto com ARSA também apresentou um foco hiperecogênico no ventrículo cardíaco esquerdo. Foi realizada ecocardiografia fetal às 16 semanas de gestação, que confirmou o diagnóstico de ARSA e foco hiperecogênico. A amniocentese revelou cariótipo normal, 46, XX. CONCLUSÃO: É possível fazer o diagnóstico de ARSA na ecografia do primeiro trimestre. O nosso único caso de ARSA apresentou um cariótipo normal sem malformações cardíacas associadas.

Oxidation of the albumin thiol to sulfenic acid and its implications in the intravascular compartment

Human serum albumin (HSA) is the most abundant protein in the intravascular compartment. It possesses a single thiol, Cys34, which constitutes ~80% of the total thiols in plasma. This thiol is able to scavenge plasma oxidants. A central intermediate in this potential antioxidant activity of human serum albumin is sulfenic acid (HSA-SOH). Work from our laboratories has demonstrated the formation of a relatively stable sulfenic acid in albumin through complementary spectrophotometric and mass spectrometric approaches. Recently, we have been able to obtain quantitative data that allowed us to measure the rate constants of sulfenic acid reactions with molecules of analytical and biological interest. Kinetic considerations led us to conclude that the most likely fate for sulfenic acid formed in the plasma environment is the reaction with low molecular weight thiols to form mixed disulfides, a reversible modification that is actually observed in ~25% of circulating albumin. Another possible fate for sulfenic acid is further oxidation to sulfinic and sulfonic acids. These irreversible modifications are also detected in the circulation. Oxidized forms of albumin are increased in different pathophysiological conditions and sulfenic acid lies in a mechanistic junction, relating oxidizing species to final thiol oxidation products.

Exogenous normal lymph alleviates microcirculation disturbances and abnormal hemorheological properties in rats with disseminated intravascular coagulation

Disturbances of the microcirculation and abnormal hemorheological properties are important factors that play an important role in disseminated intravascular coagulation (DIC) and result in organ dysfunction or failure. In the present study, we established an animal model of DIC using intravenous Dextran 500 in rats, and used exogenous normal lymph corresponding to 1/15 of whole blood volume for injection through the left jugular vein. We found that normal lymph could improve the blood pressure and survival time of rats with DIC. The results regarding the mesenteric microcirculation showed that the abnormality of the diameter of mesenteric microvessels and micro-blood flow speed in the DIC+lymph group was significantly less than in the DIC+saline group. Whole blood viscosity, relative viscosity, plasma viscosity, hematocrit (Hct), erythrocyte sedimentation rate (ESR), and electrophoresis time of erythrocytes were significantly increased in the DIC+saline group compared to the control group. The electrophoretic length and migration of erythrocytes from the DIC+saline and DIC+lymph groups were significantly slower than the control group. Blood relative viscosity, Hct, ESR, and electrophoretic time of erythrocytes were significantly increased in the DIC+lymph group compared to the control group. Whole blood viscosity, relative viscosity and reduced viscosity were significantly lower in the DIC+lymph group than in the DIC+saline group, and erythrocyte deformability index was also significantly higher than in the DIC+saline and control groups. These results suggest that exogenous normal lymph could markedly improve the acute microcirculation disturbance and the abnormal hemorheological properties in rats with DIC induced by Dextran 500.