Radiofrequency ablation of large renal angiomyolipoma: median-term follow-up

PURPOSE

To study the feasibility of percutaneous radiofrequency ablation (RFA) of large angiomyolipomas (AMLs) using saline-cooled electrodes.

MATERIALS AND METHODS

Institutional Review Board approval for the study was received. Four patients (all female, age range 33-67 years) with large AMLs (maximal axis 6.1-32.4 cm) not suitable for embolotherapy or surgery consented to a trial of RFA. Procedures were performed under computerized tomographic guidance using 14G saline-infused electrodes. Two ablations (diameter 4-7 cm) were undertaken in each patient. Variables studied were technical success, treatment safety, alteration of tumor consistency, tumor size, effect on renal function, and medium-term freedom from haemorrhage.

RESULTS

All four patients underwent successful RFA without any intraprocedural complications. There has been no haemorrhage, or new renal specific symptom, during a minimum 48-month period, and normal renal function has been normal. On follow-up radiological imaging, the tumors have become fattier with involution of the soft-tissue elements (soft tissue-to-total tumor ratio decreased mean [range] of 0.26 [0.14-0.48] to 0.17 [0.04-0.34] U; p = 0.04 [paired Student t test]). Further evidence of treatment effect was the development of a capsule around the ablation zone, but there was no change in overall tumor volume (mean [range] 1,120 [118-2,845] to 1150 [90-3,013] ml; p = 1 [paired Student t test]).

CONCLUSION

RFA of large AMLs is technically feasible using saline-infused electrodes. The soft-tissue elements decreased in volume; the tumors become fattier; and there has been no renal haemorrhage during a 48-month period.

Investigation of erectile dysfunction

Erectile dysfunction (ED) represents a common and debilitating condition with a wide range of organic and non-organic causes. Physical aetiologies can be divided into disorders affecting arterial inflow, the venous occlusion mechanism or the penile structure itself. Various imaging modalities can be utilised to investigate the physical causes of ED, but penile Doppler sonography (PDS) is the most informative technique, indicated in those patients with ED who do not respond to oral pharmacological agents (e.g. phosphodiesterase type 5 inhibitors). This review will examine the anatomical and physiological basis of penile erection, the method for performing PDS and features of specific causes of ED, and will also consider the alternative imaging modalities available.

Priapism: pathophysiology and the role of the radiologist

Priapism is defined as a penile erection that persists for 4 h or longer and is unrelated to sexual activity. Its identification is important as lack of timely treatment (particularly of the low flow/ischaemic subgroup) can result in persisting erectile dysfunction as a consequence of irreversible corporal fibrosis. This review describes the physiology and anatomy of the normal erection, the aetiology and pathophysiology of the different types of priapism, and the role of the radiologist in the management of the condition. The treatment of iatrogenic priapism following intracavernosal injection of pharmacostimulant is discussed.

Applications of transrectal ultrasound in prostate cancer

Transrectal ultrasound (TRUS) was first developed in the 1970s. TRUS-guided biopsy, under local anaesthetic and prophylactic antibiotics, is now the most widely accepted method to diagnose prostate cancer. However, the sensitivity and specificity of greyscale TRUS in the detection of prostate cancer is low. Prostate cancer most commonly appears as a hypoechoic focal lesion in the peripheral zone on TRUS but the appearances are variable with considerable overlap with benign lesions. Because of the low accuracy of greyscale TRUS, TRUS-guided biopsies have become established in the acquisition of systematic biopsies from standard locations. The number of systematic biopsies has increased over the years, with 10-12 cores currently accepted as the minimum standard. This article describes the technique of TRUS and biopsy and its complications. Novel modalities including contrast-enhanced modes and elastography as well as fusion techniques for increasing the sensitivity of TRUS-guided prostate-targeted biopsies are discussed along with their role in the diagnosis and management of prostate cancer.

Transparent conducting films from NbSe3 nanowires

We have developed methods to disperse and partially size separate NbSe(3) nanowires in aqueous surfactant solutions. These dispersions can easily be formed into thin films. Optical and electrical studies show these films to display sheet resistances and transmittances ranging from (460 Ω/□, 22%) to (12 kΩ/□, 79%) depending on thickness. For thicker films, we measured the transparent conducting figure of merit to be σ(DC, B)/σ(Op) = 0.32, similar to graphene networks. Thickness measurements gave individual values of σ(Op) = 17,800 S m(-1) and σ(DC, B) = 5700 S m(-1). Films thinner than ∼ 70 nm displayed reduced DC conductivity due to percolative effects.

Diagnostic accuracy and value of magnetic resonance imaging (MRI) in planning exenterative pelvic surgery for advanced colorectal pelvic cancer

370

Background: Exenterative pelvic surgery is challenging and has been used in colorectal surgery to manage patients with advanced colorectal pelvic cancer. Resection of the tumor needs to be performed en-bloc and if feasible, without exposing the tumor, since this can compromise resection margins. This can only be performed through careful pre-operative staging. This study aimed to assess the diagnostic accuracy of MRI in detecting colorectal tumor invasion into seven intrapelvic compartments and its value in planning exenterative pelvic surgery.

Methods: Sixty four consecutive patients underwent preoperative MRI planning for exenterative surgery, for locally advanced (n= 23) and recurrent (n= 41) pelvic colorectal cancer. Two radiologists reported tumor invasion for each of the seven anatomic surgical resection compartments and were blinded to histopathology and intraoperative reference standards. Sensitivity, specificity and predictive values were calculated for each compartments. Kaplan-Meier methodology was used to calculate survival rates. Interobserver agreement was assessed using Cohen's Kappa coefficient (k).

Results: The sensitivity of MRI was ≥93.3% in all except for the lateral compartment where it was 89.3%. Its specificity for the posterior (82.2%), anterior below (86.4%) the peritoneal reflection compartments was lower compared to the rest of the compartments. MRI diagnosis of lateral (OR= 11.41, p= 0.033), anterior compartment above the peritoneal reflection (OR= 3.14, p= 0.005) and multicompartmental involvement (OR= 1.99, p<0.001) was associated with higher risk of incomplete resection which was subsequently found to be significant factor in predicting overall and disease free survival (p<0.05). The agreement between the two radiologists was found to be either good or very good for all the compartments (k>0.72).

Conclusions: MRI is highly accurate in predicting tumor invasion within the intrapelvic compartments and it should be the pre-operative staging modality of choice when considering exenterative surgery for patients with locally advanced colorectal pelvic cancer.

[Table: see text]

The added value of diffusion-weighted magnetic resonance imaging (DW-MRI) in the local staging of advanced colorectal pelvic cancer

378

Background: Surgeons rely on imaging to plan exenterative pelvic surgery for locally advanced primary and recurrent rectal cancer. Accurate local staging is vital in this process, as it provides information about the extent of the disease, facilitating the planning of the operation required to achieve complete resection. DW-MR imaging is a functional radiological modality that can provide indirect informationabout the water proton mobility within biologic tissue, without the need of a contrast agent. The aim of the present study was to assess the diagnostic accuracy and added value of diffusion DW-MRI in detecting colorectal tumor invasion into seven intrapelvic compartments for planning exenterative pelvic surgery.

Methods: Thirty three consecutive patients were preoperatively staged using DW-MRI to undergo exenterative surgery for locally advanced primary (n=12) and recurrent (n=21) colorectal pelvic cancer. Two radiologists reported tumor invasion for each of the seven anatomic surgical resection compartments and were blinded to histopathology and intraoperative reference standards. Accuracy, sensitivity, specificity and predictive values were calculated for the seven intrapelvic compartments. Interobserver agreement was assessed using Cohen's Kappa (k) coefficient for each compartment.

Results: The sensitivity of DW-MRI when used alone was low for all the compartments except the central (92%). Its specificity was very high for all the compartment (≥89.5%). Combining DW-MRI with conventional MRI increased the sensitivity for the lateral compartment by 8.3% to 100% and the specificity for the anterior compartment below the peritoneal reflection by 9.1% to 90.9%. The overall incremental value for the lateral compartment was 3%. The interobserver agreement was either good or very good (k≥0.669; p<0001) for all the compartments.

Conclusions: DW-MRI can improve the diagnostic accuracy of conventional MRI when staging patients with advanced colorectal pelvic cancer. Diffusion images are cheap and easy to obtain. Therefore DW-MRI should always be used in combination with conventional MRI when considering patients for exenterative pelvic surgery.

No significant financial relationships to disclose.

Magnetoresistance anisotropy of a one-dimensional superconducting niobium strip

We investigated confinement effects on the resistive anisotropy of a superconducting niobium strip with a rectangular cross section. When its transverse dimensions are comparable to the superconducting coherence length, the angle dependent magnetoresistances at a fixed temperature can be scaled as R(theta,H) = R(H/Hctheta) where Hctheta =Hc0(cos2theta + gamma(-2)sin2theta)(-1/2) is the angular dependent critical field, gamma is the width to thickness ratio, and Hc0 is the critical field in the thickness direction at theta=0 degrees . The results can be understood in terms of the anisotropic diamagnetic energy for a given field in a one-dimensional superconductor.

Systematic review of CT and MR perfusion imaging for assessment of acute cerebrovascular disease

BACKGROUND AND PURPOSE

Perfusion imaging sequences are an important part of imaging studies designed to provide information to guide therapy for treatment of cerebrovascular disease. The purpose of this study was to perform a meta-analysis of the medical literature on perfusion imaging to determine its role in clinical decision making for patients with acute cerebral ischemia.

MATERIALS AND METHODS

We searched MEDLINE by using a strategy that combined terms related to perfusion imaging with terms related to acute cerebral ischemia and brain tumors. We identified 658 perfusion imaging articles and classified them according to the clinical usefulness criteria of Thornbury and Fryback. We found 59 articles with promise of indicating usefulness in clinical decision making. We devised and implemented a clinical decision making scoring scale more appropriate to the topic of acute cerebral ischemia.

RESULTS

Several articles provided important insights into the physiologic processes underlying acute cerebral ischemia by correlation of initial perfusion imaging deficits with clinical outcome or ultimate size of the infarct. However, most articles showed relatively low relevance to influencing decisions in implementing treatment.

CONCLUSION

Most perfusion imaging articles are oriented toward important topics such as optimization of imaging parameters, determination of ischemia penumbra, and prediction of outcome. However, information as to the role of perfusion imaging in clinical decision making is lacking. Studies are needed to demonstrate that use of perfusion imaging changes outcome of patients with acute cerebral ischemia.

Hormonal factors concerned with liver regeneration

Hepatic regeneration in partially hepatectomized, eviscerated rats, and survival in mice infected with lethal doses of murine hepatitis virus, are both strikingly promoted by combined administration of insulin and glucagon. These two hormones, although potent promotors, fail as initiators of hepatocyte proliferation in animals with intact liver, which suggests a requirement for additional factors, probably derived from non-portal-splanchnic organs. We now find that continous intraperitoneal infusion of epidermal growth factor (EGF) initiates DNA synthesis, as determined by incorporation of [3H] thymidine, in livers of adult rats in vivo. The rise in DNA labelling, which is small with EGF alone, is augmented by addition to the infusion of either glucagon or insulin. This is in agreement with reports on adult hepatocytes in culture. Whether EGF has a physiological role in regulating liver growth under normal conditions in vivo remains to be determined.

A non-invasive method for detecting the metabolic stress response in rodents: characterization and disruption of the circadian corticosterone rhythm

Plasma corticosterone (CORT) measures are a common procedure to detect stress responses in rodents. However, the procedure is invasive and can influence CORT levels, making it less than ideal for monitoring CORT circadian rhythms. In the current paper, we examined the applicability of a non-invasive fecal CORT metabolite measure to assess the circadian rhythm. We compared fecal CORT metabolite levels to circulating CORT levels, and analyzed change in the fecal circadian rhythm following an acute stressor (i.e. blood sampling by tail veil catheter). Fecal and blood samples were collected from male adolescent rats and analyzed for CORT metabolites and circulating CORT respectively. Fecal samples were collected hourly for 24 h before and after blood draw. On average, peak fecal CORT metabolite values occurred 7-9 h after the plasma CORT peak and time-matched fecal CORT values were well correlated with plasma CORT. As a result of the rapid blood draw, fecal production and CORT levels were altered the next day. These results indicate fecal CORT metabolite measures can be used to assess conditions that disrupt the circadian CORT rhythm, and provide a method to measure long-term changes in CORT production. This can benefit research that requires long-term glucocorticoid assessment (e.g. stress mechanisms underlying health).