Unilateral pulmonary oedema after minimally invasive and robotically assisted mitral valve surgery.

OBJECTIVES: Unilateral pulmonary oedema (UPO) is a severe complication of minimally invasive cardiac surgery. UPO rates and UPO-related mortality vary considerably between different studies. Due to lack of consistent diagnostic criteria for UPO, the aim of this study was to create a reproducible radiological classification for UPO. Also, risk factors for UPO after robotic and minimally invasive mitral valve operations were evaluated. METHODS: Two hundred and thirty-one patients who underwent elective minimally invasive mitral valve surgery between January 2009 and March 2017 were evaluated. Chest radiographs of the first postoperative morning were categorized into 3 UPO grades based on the severity of radiological signs of pulmonary oedema described in this study. The radiographs were analysed by 2 independent radiologists and interobserver agreement was evaluated. The clinical significance of the classification was evaluated by comparing postoperative PaO2/FiO2 values and total ventilation times between the different UPO grades. Also, multivariable logistic regression analysis was employed to identify risk factors for UPO. RESULTS: Interobserver agreement was substantial (Kappa = 0.780). Median total ventilation times were significantly longer with increasing severity of UPO, 15 (interquartile range 12-18) h for no UPO, 18 (interquartile range 15-24) h for grade I UPO and 25 (interquartile range 21-31) h for grade II UPO. Pulmonary hypertension [adjusted odds ratios (AOR) 2.51, 95% confidence intervals (CI) 1.43-4.40; P = 0.001], moderate or severe heart failure (AOR 2.88, 95% CI 1.27-6.53; P = 0.011), body mass index (AOR 1.14, 95% CI 1.02-1.28; P = 0.017) and cardiopulmonary bypass time (AOR 1.02, 95% CI 1.01-1.03; P < 0.001) were identified as independent risk factors for UPO and robotic approach (AOR 0.27, 95% CI 0.12-0.62; P = 0.002) as protective against UPO. CONCLUSIONS: Due to the variability of the diagnostic criteria for UPO in previous studies, a radiological classification for UPO is required to reliably assess the rates and risk factors for UPO. The radiological classification described in this study demonstrated high interobserver agreement and correlated with total ventilation times and postoperative PaO2/FiO2 values.

Metabolite phantom correction of the nonuniform volume-selection profiles in MR spectroscopic imaging: application to temporal lobe epilepsy.

BACKGROUND AND PURPOSE: In MR spectroscopic imaging (MRSI), the volume-selection profiles of metabolites differ from each other. These differences cause variations in metabolite intensities, which are particularly prominent when the hippocampi are evaluated. We hypothesize that the errors arising from these effects cause notable artifact when temporal lobe epilepsy (TLE) is lateralized with MRSI. METHODS: We examined a metabolite phantom, control subjects, and patients with TLE by using MRSI. We calculated the error arising from the different volume-selection profiles of metabolites in vitro and evaluated this correction in the examination of the control subjects and in the lateralization of epilepsy in the patients. RESULTS: Without a correction, a considerable error in the metabolite content existed, even deep inside the spectroscopic volume of interest. The result was false asymmetry (P < .008) in the hippocampi of control subjects. Among the 11 patients, TLE was correctly lateralized in three only after the correction was made, and in one, TLE was incorrectly lateralized. CONCLUSION: The volume-selection profiles of N-acetylaspartate, choline, and creatine differ enough to cause a significant error, even in the metabolite ratios, when patients with TLE are examined with MRSI. We propose a simple phantom method to correct for this error without a need to modify the pulse sequence.