Three-Dimensional Multi-Frequency Shear Wave Absolute Vibro-Elastography (3D S-WAVE) With a Matrix Array Transducer: Implementation and Preliminary In Vivo Study of the Liver.

Magnetic resonance elastography (MRE) is commonly regarded as the imaging-based gold-standard for liver fibrosis staging, comparable to biopsy. While ultrasound-based elastography methods for liver fibrosis staging have been developed, they are confined to a 1D or a 2D region of interest and to a limited depth. 3D Shear Wave Absolute Vibro-Elastography (S-WAVE) is a steady-state, external excitation, volumetric elastography technique that is similar to MRE, but has the additional advantage of multi-frequency excitation. We present a novel ultrasound matrix array implementation of S-WAVE that takes advantage of 3D imaging. We use a matrix array transducer to sample axial multi-frequency steady-state tissue motion over a volume, using a Color Power Angiography sequence. Tissue motion with the frequency components {40,50,60} and {45,55,65} Hz are acquired over a (90° lateral) × (40° elevational) × (16 cm depth) sector with an acquisition time of 12 seconds. We compute the elasticity map in 3D using local spatial frequency estimation. We characterize this new approach in tissue phantoms against measurements obtained with transient elastography and MRE. Six healthy volunteers and eight patients with chronic liver disease were imaged. Their MRE and S-WAVE volumes were aligned using T1 to B-mode registration for direct comparison in common regions of interest. S-WAVE and MRE results are correlated with R2 = 0.92, while MRE and TE results are correlated with R2 = 0.71. Our findings show that S-WAVE with matrix array has the potential to deliver a similar assessment of liver fibrosis as MRE in a more accessible, inexpensive way, to a broader set of patients.

Seroprevalences of hepatitis B virus and hepatitis C virus among participants of an Asian health fair in the Lower Mainland, British Columbia.

BACKGROUND: The seroprevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) are 0.4% and 0.8%, respectively, in Canada, but varying rates have been reported in different populations. OBJECTIVES: To determine the seroprevalences of HBV and HCV among attendees of an Asian health fair in the Lower Mainland, British Columbia, as well as to correlate questionnaire answers regarding vaccination status to serological profiles. METHODS: Attendees at an Asian health fair were invited to participate in the present study on a voluntary basis. They provided answers to a questionnaire including ethnicity and vaccination status. Blood was then drawn for HBV and HCV serology. Active HBV was defined as HBV surface antigen (HBsAg) positive while HCV seroprevalence was defined as HCV antibody reactive. Previous exposure to HBV was defined as HBV core antibody (anti-HBc) positive and HBsAg negative. Nonimmunity was defined as anti-HBc negative and HBV surface antibody negative. Only those with correct demographic information matched to serological results were included in the study. RESULTS: There were 192 consenting attendees of the fair, of whom 112 were included in the study. Of the participants, 91% were Chinese. Active HBV infection was found in three participants (2.7% [95% CI 0.6% to 7.6%]) and HCV infection was found in two participants (1.8% [95% CI 0.2% to 6.3%]). More than 40% of participants had been previously exposed to HBV (42% [95% CI 33% to 51%]). Almost 20% demonstrated nonimmunity to HBV (19% [95% CI 12% to 27%]). There was significant discordance when questionnaire answers regarding vaccination status were compared with serological profiles. CONCLUSION: The seroprevalences of HBV and HCV in this cohort were 2.7% and 1.8%, respectively - higher than nationally reported rates. Our results highlight that the lack of knowledge of HBV infection and vaccination status remains a significant clinical issue in the Asian community of British Columbia.

HISTORIQUE: La séroprévalence des virus de l'hépatite B (VHB) et de l'hépatite C (VHC) s'élève à 0,4 % et à 0,8 %, respectivement, au Canada, mais les taux sont variables dans diverses populations. OBJECTIFS: Déterminer la séroprévalence du VHB et du VHC chez les participants à une foire asiatique sur la santé du Lower Mainland, en Colombie-Britannique, et lier les réponses au questionnaire sur le statut vaccinal avec les profils sérologiques. MÉTHODOLOGIE: Les participants à une foire asiatique sur la santé ont été invités à participer volontairement à l'étude. Ils ont répondu à un questionnaire contenant des questions sur l'ethnie et le statut vaccinal. Du sang a ensuite été prélevé en vue d'une sérologie du VHB et du VHC. Le VHB actif était défini comme un résultat positif à l'antigène de surface du VHB (AgHBs), tandis que la séroprévalence du VHC était définie comme une réaction aux anticorps anti-VHC. Une exposition passée au VHB était définie comme un résultat positif à l'antigène capsidique du VHB (anti-HBc) et négatif à l'AgHBs. La non-immunité était définie comme des résultats négatifs à l'anti-HBc et à l'anticorps de surface du VHB. Seulement ceux dont l'information démographique exacte correspondait aux résultats sérologiques ont participé à l'étude. RÉSULTATS: Au total, 192 participants consentants ont participé à la foire, dont 112 à l'étude. Des participants, 91 % étaient Chinois. Trois étaient atteints d'une infection active par le VHB (2,7 % [95 % IC 0,6 % à 7,6 %]) et deux, d'une infection par le VHC (1,8 % [95 % IC 0,2 % à 6,3 %]). Plus de 40 % des participants avaient déjà été exposés au VHB (42 % [95 % IC 33 % à 51 %]). Près de 20 % ont démontré une non-immunité au VHB (19 % [95 % IC 12 % à 27 %]). On constatait une importante discordance entre les réponses au questionnaire sur le statut vaccinal et les profils sérologiques. CONCLUSION: La séroprévalence du VHB et le VHC de cette cohorte s'élevait à 2,7 % et à 1,8 %, respectivement, soit des résultats plus élevés que les taux nationaux. Ces résultats font ressortir que l'absence de connaissances sur l'infection par le VHB et le statut vaccinal demeure un problème clinique significatif dans la communauté asiatique de la Colombie-Britannique.

Efficacy of maintenance subcutaneous hepatitis B immune globulin (HBIG) post-transplant for prophylaxis against hepatitis B recurrence.

BACKGROUND: Patients who receive liver transplantation for chronic hepatitis B infection require long-term combination therapy with hepatitis B immunoglobulin (HBIG) and oral antiviral medication to prophylax against graft re-infection. This study examines the efficacy and patient preference of subcutaneous (SC) administration of HBIG in maintaining anti HBs titres > 100 IU/L. MATERIALS AND METHODS: 12 patients who were stable while receiving our standard IM HBIG protocol received an alternate formulation by SC injection, consisting of 10 mL (3120 IU) HBIG as 4 x 2.5 mL SC injections. SC injection were repeated as soon as titres reached 100-150 IU/mL during the 3 month study period. A questionnaire was administered upon study entry and exit to subjectively assess patient preference. RESULTS: Anti- HBs Cmax after first injection was 441.6 IU/L +/- 81.5, and Tmax was 7.1 +/- 3.2 days. SC injections were required every 56 days, which compared well to the frequency of required IM injections prior to study enrollment of 45 days. The patients mean ratings of pain on a 0-10 scale were 5 for the IM route and 1.6 for the SC route. All patients preferred the SC injections to the IM. CONCLUSION: SC administration of HBIG can effectively maintain anti HBs levels above the requisite 100 IU/L while substantially decreasing patient discomfort and improving patient satisfaction, and therefore becomes a very attractive alternative to IM HBIG injections. Further studies and wider use of SC HBIG based on this study may alter the standard practice of transplantation centers