Xenon-enhanced computed tomography quantifies normal maxillary sinus ventilation

Critical review of diagnosis in rhinology and its therapeutical implications

Diagnosis in rhinology is currently based on the concept of inflammation (chronic rhinosinusitis [CRS]) or the clinical concept of chronic nasal dysfunction (CND). The complementarity between these two approaches can be discussed by a critical review of the literature structured by the analysis of the fundamental and diagnostic bases and the therapeutic implications linked to each. The concept of CRS is based on the anatomical continuity of the nasal and sinus respiratory mucosa and molecular biology data, seeking to analyze the mechanisms of chronic inflammation and to identify proteins and biomarkers involved in the different supposed endotypes of chronic inflammation of this mucosa. The concept of CND seeks to analyze medical, instrumental or surgical diagnostic and therapeutic strategies, taking account of both inflammatory and non-inflammatory causes impacting the anatomy or physiology of each of the three noses (olfactory, respiratory and sinus) that make up the mid-face sinonasal organ of evolution-development (Evo-Devo) theory. Thus, the concept of CRS offers an endotypic approach, based on biological characterization of mucosal inflammation, while the concept of CND offers a compartmentalized phenotypic and pathophysiological approach to sinonasal diseases. The joint contribution of these two concepts in characterizing nasal functional pathology could in future improve the medical service provided to patients.

Nasal polyposis (or chronic olfactory rhinitis)

The concept of chronic rhinosinusitis with or without polyps is founded on the structural and functional unicity of the pituitary mucosa and its united response to environmental aggression by allergens, viruses, bacteria, pollution, etc. The present review sets this concept against the evo-devo three-nose theory, in which nasal polyposis is distinguished as specific to the olfactory nose and in particular to the non-olfactory mucosa of the ethmoid, which is considered to be not a sinus but rather the skull-base bone harboring the olfactory mucosa. The evo-devo approach enables simple and precise positive diagnosis of nasal polyposis and its various clinical forms, improves differential diagnosis by distinguishing chronic diseases of the respiratory nose and those of the paranasal sinuses, hypothesizes an autoimmune origin specifically aimed at olfactory system auto-antigens, and supports the surgical concept of nasalization against that of functional sinus and ostiomeatal-complex surgery. The ventilation function of the sinuses seems minor compared to their production, storage and active release of nitric oxide (NO) serving to oxygenate arterial blood in the pulmonary alveoli. This respiratory function of the paranasal sinuses may indeed be their most important. NO trapped in the ethmoidal spaces also accounts for certain radiographic aspects associated with nasal polyposis.

Sinusology

This paper presents a brief history of the successive anatomical, physiological and pathophysiological concepts about the paranasal sinuses. Sinusology, the science of the paranasal sinuses, is founded on scientific work on the production of nitric oxide (NO) by the sinuses and on the evo-devo theory of their formation. The paranasal sinuses seem to develop after regression of the erythropoietic marrow in the maxillary, frontal and sphenoid bones and its replacement by cavities filled with gas, which escapes into the nasal fossae through the ostium. The sinus epithelium synthesizes NO continuously. The paranasal sinus cavities form a compartmentalized reservoir of NO, which is released discontinuously in boli after an opening of the ostium. Ostium opening can be induced by sound vibration, either internal (humming) or external (an acoustic vibration added to the in-breath). NO plays the role of an "aerocrine" messenger between the upper and lower respiratory tracts, reducing pulmonary vascular resistance and facilitating alveolar oxygen transfer into the bloodstream. Its physiological role in arterial blood oxygenation could be involved in speech and singing or be activated by physiological snoring during sleep. Rhinology, the science of the nose, in which the evo-devo concept distinguishes the respiratory and the olfactory nose, is now backed up by sinusology.

Correlation between hepatic blood flow and liver function in alcoholic liver cirrhosis

AIM: To elucidate the correlation between hepatic blood flow and liver function in alcoholic liver cirrhosis (AL-LC).

METHODS: The subjects included 35 patients with AL-LC (34 men, 1 woman; mean age, 58.9 ± 10.7 years; median age, 61 years; range: 37-76 years). All patients were enrolled in this study after obtaining written informed consent. Liver function was measured with tests measuring albumin (Alb), prothrombin time (PT), brain natriuretic peptide (BNP), branched amino acid and tyrosine ratio (BTR), branched chain amino acid (BCAA), tyrosine, ammonia (NH₃), cholinesterase (ChE), immunoreactive insulin (IRI), total bile acid (TBA), and the retention rate of indocyanine green 15 min after administration (ICG R15). Hepatic blood flow, hepatic arterial tissue blood flow (HATBF), portal venous tissue blood flow (PVTBF), and total hepatic tissue blood flow (THTBF) were simultaneously calculated using xenon computed tomography.

RESULTS: PVTBF, HATBF and THTBF were 30.2 ± 10.4, 20.0 ± 10.7, and 50.3 ± 14.9 mL/100 mL/min, respectively. Alb, PT, BNP, BTR, BCAA, tyrosine, NH₃, ChE, IRI, TBA, and ICG R15 were 3.50 ± 0.50 g/dL, 72.0% ± 11.5%, 63.2 ± 56.7 pg/mL, 4.06 ± 1.24, 437.5 ± 89.4 μmol/L, 117.7 ± 32.8 μmol/L, 59.4 ± 22.7 μg/dL, 161.0 ± 70.8 IU/L, 12.8 ± 5.0 μg/dL, 68.0 ± 51.8 μmol/L, and 28.6% ± 13.5%, respectively. PVTBF showed a significant negative correlation with ICG R15 (r = -0.468, P <0.01). No significant correlation was seen between ICG 15R, HATBF and THTBF. There was a significant correlation between PVTBF and Alb (r = 0.2499, P < 0.05), and NH₃ tended to have an inverse correlation with PVTBF (r = -0.2428, P = 0.0894). There were also many significant correlations between ICG R15 and liver function parameters, including Alb, NH3, PT, BNP, TBA, BCAA, and tyrosine (r = -0.2156, P < 0.05; r = 0.4318, P < 0.01; r = 0.4140, P < 0.01; r = 0.3610, P < 0.05; r = 0.5085, P < 0.001; r = 0.4496, P < 0.01; and r = 0.4740, P < 0.05, respectively).

CONCLUSION: Our investigation showed that there is a close correlation between liver function and hepatic blood flow.

Xenon computed tomography can evaluate the improvement of hepatic hemodynamics before and after endoscopic injection sclerotherapy

BACKGROUND

Xenon computed tomography (Xe-CT) provides quantitative information on tissue blood flow (TBF). In the present study, Xe-CT was performed in patients with esophagogastric varices (EGV) before and after endoscopic injection sclerotherapy (EIS) to evaluate hepatic blood flow (HBF), hepatic arterial TBF (HATBF) and portal venous TBF (PVTBF).

METHODS

Subjects comprised of 88 patients with EGV (49 men, 39 women, average age 65.8 ± 11.5 years, median age 68 years, 30-86 years) and liver cirrhosis related to either hepatitis C virus (C) (n = 33), hepatitis B virus (B) (n = 3), alcohol (AL) (n = 22), AL + C (n = 7), AL + B (n = 1), B + C + AL (n = 1), nonalcoholic steatohepatitis (NASH) (n = 4), autoimmune hepatitis (AIH) (n = 5), primary biliary cirrhosis (PBC) (n = 2), or cryptogenic (n = 10) were enrolled. All patients, who were enrolled in this study, were performed EIS for prophylaxis. Xe-CT and measurement of the retention rate of indocyanine green 15 min after administration (ICG R15) were performed before and after EIS. Total hepatic TBF (THTBF) and PVTBF/HATBF ratio (P/A) were also calculated.

RESULTS

PVTBF, HATBF, THTBF, P/A and ICG R15 before EIS were 28.3 ± 8.91, 22.5 ± 14.4 and 50.8 ± 17.6 ml/100 ml/min, 1.62 ± 0.71 and 28.8 ± 12.7 %, respectively and those after EIS were 31.9 ± 10.0, 19.3 ± 11.6, and 51.2 ± 17.0 ml/100 ml/min, 1.92 ± 0.84 and 23.6 ± 11.3 %, respectively. PVTBF and P/A after EIS were significantly higher than those before EIS (p = 0.00444, p = 0.0179, respectively), and HATBF and ICG R15 after EIS were significantly lower than those before EIS (p = 0.00129, p < 0.001, respectively).

CONCLUSIONS

Xenon computed tomography showed that PVTBF increased after EIS for EGV and HATBF decreased in response to an increase in PVTBF.

Prospective evaluation of aerosol delivery by a powered nasal nebulizer in the cadaver model

BACKGROUND

The objective of this study was to compare the distribution of aerosol delivered via a powered nasal nebulizer device in 5 fresh frozen-cadaver heads (10 total sides).

METHODS

Nasoneb® (Medinvent, St. Paul, MN) was used to deliver a total volume of 10 mL (9 mL saline and 1 mL of 10% fluorescein). Aerosol distribution was assessed in 3 trials: (1) unoperated nose; (2) post-functional endoscopic sinus surgery (FESS); and (3) post-FESS with endoscopic modified Lothrop procedure (EML). Two independent observers rated the distribution of the fluorescein-dyed saline in the anterior nasal cavity (ANC), olfactory cleft (OC), middle meatus (MM), sphenoethmoid recess (SER), nasopharynx (NP), along with maxillary sinus (MS), ethmoid cavity (EC), sphenoid sinus (SS), frontal sinus (FS), and frontal neo-ostium (F-NEO) in the operated specimens.

RESULTS

The nebulizer consistently delivered aerosolized saline to the ANC, MM/EC, and SER/SS across the 3 trials. A statistically significant increase in delivery was noted to the MM (p = 0.044) post-FESS. In addition, a statistically significant increase in delivery to the F-NEO was noted post-FESS with EML (p = 0.001). Multiplicity adjustment done for the FESS group showed statistically superior delivery to the EC vs OC (p = 0.031) and FS (p = 0.02) and to the SS vs FS (p = 0.031). Multiplicity adjustment after FESS with EML improved delivery to the FS, resulting in no statistical difference in aerosol delivery between F-NEO and EC or SS.

CONCLUSION

The nebulizer consistently delivered aerosolized saline to multiple nasal subsites, with improvement in delivery seen to the middle meatal region after FESS and F-NEO after FESS with EML. This may have important implications for the delivery of topical medications to the paranasal sinuses in the postoperative setting.

Evaluation of quantitative portal venous, hepatic arterial, and total hepatic tissue blood flow using xenon CT in alcoholic liver cirrhosis-comparison with liver cirrhosis related to hepatitis C virus and nonalcoholic steatohepatitis

BACKGROUND/AIMS

Xenon computed tomography (Xe-CT) is a noninvasive method of quantifying and visualizing tissue blood flow (TBF). For the liver, Xe-CT allows separate measurement of hepatic arterial and portal venous TBF. The present study evaluated the usefulness of Xe-CT as a noninvasive diagnostic procedure for measuring hepatic TBF in alcoholic liver cirrhosis (AL-LC), compared with liver cirrhosis related to nonalcoholic steatohepatitis (NASH), (NASH-LC), and hepatitis C virus (HCV), (C-LC).

METHODS

Xe-CT was performed on 22 patients with AL-LC, 7 patients with NASH-LC, and 24 patients with C-LC. Severity of LC was classified according to Child-Pugh classification. Correlations between hepatic TBF, Child-Pugh classification, and indocyanin green retention (ICG) rate after 15 minutes (ICG15R) were examined. Correlations of hepatic TBF in Child-Pugh class A to AL-LC, NASH-LC, and C-LC were also examined.

RESULTS

Portal venous TBF (PVTBF) displayed a significant negative correlation with Child-Pugh score and ICG15R (r = -0.432, p < 0.01, r = -0.442, p < 0.01, respectively). Moreover, ICG15R displayed a significant positive correlation with Child-Pugh score (r = 0.661, p < 0.001). Meanwhile, mean PVTBF and total hepatic TBF (THTBF) was significantly lower in AL-LC than in C-LC (p < 0.05). Mean PVTBF was significantly lower in Child-Pugh class A to AL-LC and NASH-LC than in that to C-LC (p < 0.05). Similarly, mean THTBF was significantly lower in Child-Pugh class A to NASH-LC than in that to C-LC (p < 0.05).

CONCLUSIONS

Measurement of hepatic TBF using Xe-CT is useful as a noninvasive, objective method of assessing the state of the liver in chronic liver disease.

Gas monitoring in human sinuses using tunable diode laser spectroscopy

We demonstrate a novel nonintrusive technique based on tunable diode laser absorption spectroscopy to investigate human sinuses in vivo. The technique relies on the fact that free gases have spectral imprints that are about 10.000 times sharper than spectral structures of the surrounding tissue. Two gases are detected; molecular oxygen at 760 nm and water vapor at 935 nm. Light is launched fiber optically into the tissue in close proximity to the particular maxillary sinus under study. When investigating the frontal sinuses, the fiber is positioned onto the caudal part of the frontal bone. Multiply scattered light in both cases is detected externally by a handheld probe. Molecular oxygen is detected in the maxillary sinuses on 11 volunteers, of which one had constantly recurring sinus problems. Significant oxygen absorption imprint differences can be observed between different volunteers and also left-right asymmetries. Water vapor can also be detected, and by normalizing the oxygen signal on the water vapor signal, the sinus oxygen concentration can be assessed. Gas exchange between the sinuses and the nasal cavity is also successfully demonstrated by flushing nitrogen through the nostril. Advantages over current ventilation assessment methods using ionizing radiation are pointed out.

3He MR imaging of porcine paranasal sinuses

RATIONALE AND OBJECTIVES

The aim of this study was to test the effectiveness of laser-hyperpolarized helium 3 (3He) as a contrast agent for magnetic resonance (MR) imaging of porcine paranasal sinuses.

MATERIALS AND METHODS

Imaging experiments were conducted on the heads of four 50-kg Yorkshire pigs after open sinus surgery was performed. Paranasal sinus MR images were obtained with laser-polarized 3He gas produced through the spin-exchange method. The gas was delivered into the sinuses through two 14-gauge plastic catheters inserted in the nostrils. The 3He MR images were then compared with spatially correlated proton MR images.

RESULTS

The porcine paranasal sinuses were adequately depicted by MR imaging with hyperpolarized 3He. The signal intensity of the paranasal sinuses on the 3He MR images was related to the size of the opening joining the sinuses to the nasal cavity and was clearly time dependent.

CONCLUSION

Hyperpolarized 3He MR imaging may be particularly useful for identifying the anatomic configuration of the paranasal sinuses, as well as for assessing sinus aeration. Further study of the time-dependence of 3He signal intensity may help increase understanding of gas exchange in the sinuses.