Improved visualization of hepatic tumors in magnetic resonance-guided thermoablation using T1-inversion-recovery imaging with variable inversion time

OBJECTIVES

In magnetic resonance (MR)-guided interventions, visualization of hepatic lesions may be difficult using standard unenhanced T1-weighted gradient-echo volume-interpolated breath-hold (VIBE) sequence due to low contrast. Inversion recovery (IR) imaging may have the potential to improve visualization without the necessity to apply contrast agent.

METHODS

Forty-four patients (mean age 64 years, female 33%) scheduled for MR-guided thermoablation due to liver malignancies (hepatocellular carcinoma or metastases) were prospectively included in this study between March 2020 and April 2022. Fifty-one liver lesions were intra-procedurally characterized before treatment. Unenhanced T1-VIBE was acquired as part of the standard imaging protocol. Additionally, T1-modified look-locker images were acquired with eight different inversion times (TI) between 148 and 1743 ms. Lesion-to-liver contrast (LLC) was compared between T1-VIBE and IR images for each TI. T1 relaxation times for liver lesions and liver parenchyma were calculated.

RESULTS

Mean LLC in T1-VIBE sequence was 0.3 ± 0.1. In IR images, LLC was highest at TI 228 ms (1.04 ± 1.1) and significantly higher compared to T1-VIBE (p < 0.001). In subgroup analysis, lesions of colorectal carcinoma showed the highest LLC at 228 ms (1.14 ± 1.4), and hepatocellular carcinoma showed the highest LLC at 548 ms (1.06 ± 1.16). T1-relaxation times in liver lesions were higher compared to the adjacent liver parenchyma (1184 ± 456 vs. 654 ± 96 ms, p < 0.001).

CONCLUSIONS

IR imaging is promising to provide improved visualization during unenhanced MR-guided liver interventions compared to standard T1-VIBE sequence when using specific TI. Low TI between 150 and 230 ms yields the highest contrast between liver parenchyma and malignant liver lesions.

CLINICAL RELEVANCE STATEMENT

Improved visualization of hepatic lesions during MR-guided percutaneous interventions using inversion recovery imaging without the necessity to apply contrast agent.

KEY POINTS

• Inversion recovery imaging is promising to provide improved visualization of liver lesions in unenhanced MRI. • Planning and guidance during MR-guided interventions in the liver can be performed with greater confidence without necessity to apply contrast agent. • Low TI between 150 and 230 ms yields the highest contrast between liver parenchyma and malignant liver lesions.

MRI-guided percutaneous thermoablation as first-line treatment of recurrent hepatic malignancies following hepatic resection: single center long-term experience

PURPOSE

Hepatic recurrence of liver malignancies is a leading problem in patients after liver resection with curative intention. Thermoablation is a promising treatment approach for patients after hepatic resection, especially in liver-limited conditions. This study aimed to investigate safety, survival, and local tumor control rates of MRI-guided percutaneous thermoablation of recurrent hepatic malignancies following hepatic resection.

MATERIAL AND METHODS

Data from patients with primary or secondary hepatic malignancies treated between 2004 and 2018 with MRI-guided percutaneous thermoablation of hepatic recurrence after prior hepatic resection were retrospectively analyzed. Disease-free survival and overall survival rates were calculated using the Kaplan-Meier method.

RESULTS

A total of 57 patients with hepatic recurrence (mean tumor size = 18.9 ± 9.1 mm) of colorectal cancer liver metastases (n = 27), hepatocellular carcinoma (n = 17), intrahepatic recurrence of cholangiocellular carcinoma (n = 9), or other primary malignant tumor entities (n = 4) were treated once or several times with MR-guided percutaneous radiofrequency (n = 52) or microwave ablation (n = 5) (range: 1-4 times). Disease progression occurred due to local recurrence at the ablation site in nine patients (15.8%), non-local hepatic recurrence in 33 patients (57.9%), and distant malignancy in 18 patients (31.6%). The median overall survival for the total cohort was 40 months and 49 months for the colorectal cancer group, with a 5-year overall survival rate of 40.7 and 42.5%, respectively. The median disease-free survival was 10 months for both the total cohort and the colorectal cancer group with a 5-year disease-free survival rate of 15.1 and 14.8%, respectively. The mean follow-up time was 39.6 ± 35.7 months.

CONCLUSION

MR-guided thermoablation is an effective and safe approach in the treatment of hepatic recurrences in liver-limited conditions and can achieve long-term survival.

Cardiac MRI findings to differentiate athlete's heart from hypertrophic (HCM), arrhythmogenic right ventricular (ARVC) and dilated (DCM) cardiomyopathy

To provide clinically relevant criteria for differentiation between the athlete’s heart and similar appearing hypertrophic (HCM), dilated (DCM), and arrhythmogenic right-ventricular cardiomyopathy (ARVC) in MRI. 40 top-level athletes were prospectively examined with cardiac MR (CMR) in two university centres and compared to retrospectively recruited patients diagnosed with HCM (n = 14), ARVC (n = 18), and DCM (n = 48). Analysed MR imaging parameters in the whole study cohort included morphology, functional parameters and late gadolinium enhancement (LGE). Mean left-ventricular enddiastolic volume index (LVEDVI) was high in athletes (105 ml/m²) but significantly lower compared to DCM (132 ml/m²; p = 0.001). Mean LV ejection fraction (EF) was 61% in athletes, below normal in 7 (18%) athletes vs. EF 29% in DCM, below normal in 46 (96%) patients (p < 0.0001). Mean RV-EF was 54% in athletes vs. 60% in HCM, 46% in ARVC, and 41% in DCM (p < 0.0001). Mean interventricular myocardial thickness was 10 mm in athletes vs. 12 mm in HCM (p = 0.0005), 9 mm in ARVC, and 9 mm in DCM. LGE was present in 1 (5%) athlete, 8 (57%) HCM, 10 (56%) ARVC, and 21 (44%) DCM patients (p < 0.0001). Healthy athletes’ hearts are characterized by both hypertrophy and dilation, low EF of both ventricles at rest, and increased interventricular septal thickness with a low prevalence of LGE. Differentiation of athlete’s heart from other non-ischemic cardiomyopathies in MRI can be challenging due to a significant overlap of characteristics also seen in HCM, ARVC, and DCM.

Large noncollinearity and spin reorientation in the novel Mn2RhSn Heusler magnet

Noncollinear magnets provide essential ingredients for the next generation memory technology. It is a new prospect for the Heusler materials, already well known due to the diverse range of other fundamental characteristics. Here, we present a combined experimental and theoretical study of novel noncollinear tetragonal Mn(2)RhSn Heusler material exhibiting unusually strong canting of its magnetic sublattices. It undergoes a spin-reorientation transition, induced by a temperature change and suppressed by an external magnetic field. Because of the presence of Dzyaloshinskii-Moriya exchange and magnetic anisotropy, Mn(2)RhSn is suggested to be a promising candidate for realizing the Skyrmion state in the Heusler family.

Laparoscopic nephroureterectomy in children: a prospective study on Ligasure versus Clip/Ligation

PURPOSE

The present study was performed to compare dissection of the renal hilar vessels in laparoscopic transabdominal nephrectomy in children using the Endo-Ligasure vessel sealing system versus clip/ligation.

PATIENTS AND METHODS

In a prospective and comparative study carried out from February 2003 to April 2004, 10 consecutive patients (group 1) underwent laparoscopic transabdominal nephroureterectomy using clips or intracorporeally performed ligations, respectively. From April 2004 to April 2005, 10 consecutive patients (group 2) underwent the same procedure using the Endo-Ligasure vessel sealing system. Indications for surgery were confirmed non-functioning kidneys secondary to benign unilateral renal disease and no prior surgery. The age and underlying disease distribution and the affected side were not significantly different between the two groups.

RESULTS

The operating time was significantly lower in the Endo-Ligasure group (group 1: median 167 vs. group 2: 108 min, p < 0.05). Bleeding of the renal artery occurred due to dislocation of a suture ligation, which was treated laparoscopically with an intracorporeal suture ligation. Blood loss was negligible in all patients. All procedures were completed laparoscopically and recovery was uneventful.

CONCLUSIONS

Endo-Ligasure is a beneficial tool in laparoscopic transabdominal nephrectomy. It is safe, effective, and reduces operating times compared to clip application and intracorporeal suturing.

Datenquellen in der Epidemiologie

The use of large databases has a high potential for future epidemiological research. Databases consisting of primary data as well as routine data that are mainly collected for administrative purposes will be of interest. This paper presents some large databases and some that are most relevant for epidemiological research, respectively, and shows how they might be exploited for research purposes. To make better use of large databases there are new requirements and challenges that we have to face regarding appropriate methods for their analysis. Some examples of such methods are given. An example of pharmaco-epidemiology illustrates linkage of several administrative databases and specific problems that have to be solved in this context. Finally, future challenges are discussed that have to be overcome on the way towards establishment, maintenance and analysis of large databases, especially regarding data protection, data quality and regular updates.

Anuria during pneumoperitoneum in infants and children: a prospective study

INTRODUCTION

Transient oliguria during laparoscopic surgery is a known phenomenon. Currently, no data on the impact of pneumoperitoneum on renal function in children are available.

PATIENTS AND METHODS

Thirty children with normal kidney function, who underwent laparoscopic surgery, were included in a prospective study. A transurethral catheter was placed to measure urine output during and 6 hours after operation. Renal blood flow (resistive index) was evaluated by Doppler ultrasound of a segmental renal artery before surgery, every 15 minutes during laparoscopy, and after 24 hours. Blood and urine samples were studied before and 24 hours after surgery. Hemodynamic parameters were monitored continuously during standardized anesthesia, including a standardized intravenous infusion regimen.

RESULTS

Urine output decreased within 45 minutes of pneumoperitoneum in all patients. Of 8 children younger than 1 year, 7 (88%) developed anuria vs 3 of 22 (14%) children aged 1 to 15 years (P < .001). Nine children 1 year and older (32%) developed oliguria. There was a significant recovering in the mean urine output until 5 to 6 hours after pneumoperitoneum in both age groups. No significant alterations of the renal blood flow (resistive index) and the serum and urine levels of cystatin C, creatinine, and urea nitrogen were evident until 24 hours postoperatively. The volume of infusion during pneumoperitoneum did not correlate with urine output.

CONCLUSION

Pneumoperitoneum leads to anuria in most children younger than 1 year and to oliguria in about one third of older children. This is a completely reversible phenomenon. Urine output should not be taken into consideration for calculating intravenous fluid administration during pneumoperitoneum in children.

Structure of the lipopolysaccharide core region of Hafnia alvei strains 1185 and 1204

Sugar and methylation analyses using gas chromatography/mass spectrometry and NMR spectroscopy proved that the core oligosaccharides of Hafnia alvei strains 1185 and 1204 have the following formula: carbohydrate sequence [see text] where Kdo = 3-deoxy-oct-2-ulosonic acid and P-PEtN = diphosphorylethanolamine. The structure shown above is a slight modification of the typical core region of H. alvei lipopolysaccharides. The difference refers to one sugar only: terminal galactose is present in the core of strains of 1185 and 1204, while terminal glucose in the typical core.

[Extracellular polysaccharides of coagulase-negative staphylococci and their role in pathogenicity]

Coagulase-negative staphylococci have been recognised as important pathogens in biomaterial-associated infections and a number of studies have been carried out to identify virulence factors for these microorganisms. Among them bacterial slime has been most extensively investigated, since it is considered to participate in the staphylococcal adherence and growth on polymer surfaces. It has been shown that on the surface of infected biomaterial bacteria are embedded in a heavy slime layer, that allows them to escape host defence and resist to the antimicrobial action of antibiotics. In this review article the reasons for the growing pathogenicity of coagulase-negative staphylococci are discussed. Also the methods for studying bacterial adherence and slime production are presented and the latest data on chemical composition of coagulase-negative extracellular polysaccharides are reported.

[Selective bradykinin B1 receptor block in ischemia/reperfusion of the rat pancreas]

The selective bradykinin B1-receptor-antagonist CP-0298 reduces ischemia/reperfusion induced enhanced leukocyte adherence in postcapillary venules of the pancreas, but has no influence on the microvascular perfusion failure. The postischemic enzyme release will effectively attenuated by the antagonist. Wether the activation of the B1-receptor under pathophysiological conditions exerts protective effects to maintain the integrity of the pancreas, has to be evaluated in further experiments.

Immunochemical characterization of lipopolysaccharide from glucose-nonfermenting gram-negative clinical bacterial isolate

A glucose-nonfermenting Gram-negative bacterial strain isolated from bronchofiberoscope used for examination of the patients suffering from pulmonary diseases was subjected to phenol-water extraction. Lipopolysaccharides (LPS) isolated from the water and the phenol phase differed in fatty acid composition. Both contained xylose, glucose, glucosamine and components typical for LPS, namely heptose, 3-deoxyoctulosonic acid (Kdo) and 3-hydroxymyristic acid. The presence of sphingosine in all LPS preparations classifies the strain to the genus Sphingomonas.

Immunochemical characterization of lipopolysaccharide from glucose-nonfermenting gram-negative clinical bacterial isolate

A glucose-nonfermenting Gram-negative bacterial strain isolated from bronchofiberoscope used for examination of the patients suffering from pulmonary diseases was subjected to phenol-water extraction. Lipopolysaccharides (LPS) isolated from the water and the phenol phase differed in fatty acid composition. Both contained xylose, glucose, glucosamine and components typical for LPS, namely heptose, 3-deoxyoctulosonic acid (Kdo) and 3-hydroxymyristic acid. The presence of sphingosine in all LPS preparations classifies the strain to the genus Sphingomonas.

Structural study and serological characterisation of the O-specific polysaccharide of Hafnia alvei PCM 1185, another Hafnia O-antigen that contains 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose

The O-specific polysaccharide of H. alvei strain PCM 1185 contains D-glucose, D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose, and 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucose (Qui3NAcyl) in the ratios 2:1:1:1 as well as O-acetyl groups. On the basis of sugar and methylation analyses of the polysaccharide before and after chemical modifications (O-deacetylation, carboxyl reduction, Smith degradation), as well as 1H and 13C NMR spectroscopy, including 1D sequential, selective spin-decoupling, 2D homonuclear and 13C,1H heteronuclear correlation spectroscopy (COSY), and 2D rotating-frame NOE spectroscopy, it was found that the polysaccharide has a pentasaccharide repeating unit with the following structure: [formula: see text] with O-acetyl groups present in nonstoichiometric amounts, mainly at position 2 of GlcA and position 6 of GlcNAc or lateral Glc. Serological study showed that H. alvei strain PCM 1185 can be placed in a new serotype D and that an O-acetyl group can be a part of its epitope.

[Structural and serologic characteristics of O-specific polysaccharides of Hafnia alvei PCM 1185 and 1199]

This work describes results of studies of O-specific oligosaccharide repeating units from lipopolysaccharides of two related Hafnia alvei serotypes. The linkage between O-antigen and the core region in PCM 1199 LPS has been also established. The O-acetyl residues present in the polysaccharides are involved in formation of epitopes.

Survival time models for analysing drug combination treatments

Several relative risk models for survival time data in drug combination therapy are derived and their properties are discussed. The main intention of this paper is to clarify the differences among the models in order to help to choose the appropriate one in a given situation. The models are motivated by discussing their relation to well-known physiological concepts. In an example of two-drug treatment the models are compared with each other. For this chemotherapy animal survival study, dose-risk surfaces are fitted and optimal drug combinations are estimated. Methods for checking the model assumptions are mentioned.

[The double mask]

While the consequences of occupational exposure to anesthetic gases and volatile agents on morbidity in operating room staff are controversial (survey in Swiss investigations show a distinct correlation with subjective complaints, e.g. tiredness and headache on the day of exposure (Table 1). In Sweden, rigorous control of occupational exposure to anesthetic gases has prompted development of various scavenging systems, among which the double mask (Fig. 1) is the latest and most advanced. During mask anesthesia, escaping anesthetic gases are evacuated at the point of leakage via a thin slot between a flexible silicone inner mask and a rigid plastic outer mask. A small plate in the mask produces turbulence in the otherwise laminar flow of anesthetic gases, thus reducing the speed of gas leakage. A silicone chamber is mounted on the mask and connected to a fan, requiring a flow of 35 m3/h for optimal function. This chamber does, however, also associate the system with two practical problems: the system with its evacuation tube is heavier to hold than conventional masks, and it is associated with increased dead-space that is only partly minimized by a modification of the Y-connector. While the handling is largely a matter of routine and the weight of the system is minimized when the evacuation tube is arranged to draw slightly upward, the increased dead space may reduce the practicality of the double mask in infants.