Susanne Sloth Osther

Characterization of complex renal cysts: A critical evaluation of the Bosniak classification

Abstract Objective. Complex renal cysts represent a major clinical problem, since it is often difficult to exclude malignancy. The Bosniak classification system, based on computed tomography (CT), is widely used to categorize cystic renal lesions. The aim of this study was to evaluate critically available data on the Bosniak classification. Material and methods. All publications from an Entrez Pubmed search were reviewed, focusing on clinical applicability and the use of imaging modalities other than CT to categorize complex renal cysts. Results. Fifteen retrospective studies were found. Most series were small, with only six studies comprising more than 30 patients. When the results of these six studies were pooled the percentage of malignancy was: category I, 0%; category II, 15.6%; category IIF, 0%; category III, 65.3%; and category IV, 91.7%. Category IIF was included in only three studies. Both magnetic resonance imaging and contrast-enhanced ultrasonography (US) seemed to have reasonable agreement with CT, although both modalities had a tendency to upgrade lesions. Conclusions. The main problem with the Bosniak classification is in separating category II and III lesions, which is of major importance, since decisions on intervention are based on this separation. The use of category IIF seems promising to detect those category II lesions that eventually will develop into malignancy and reduce overtreatment of lesions originally classified as category III. The scientific basis of this “new” classification strategy is, however, still missing. Data on other imaging modalities are too limited for conclusions to be drawn.

Bosniak classification system: a prospective comparison of CT, contrast-enhanced US, and MR for categorizing complex renal cystic masses

Background The Bosniak classification was originally based on computed tomographic (CT) findings. Magnetic resonance (MR) and contrast-enhanced ultrasonography (CEUS) imaging may demonstrate findings that are not depicted at CT, and there may not always be a clear correlation between the findings at MR and CEUS imaging and those at CT. Purpose To compare diagnostic accuracy of MR, CEUS, and CT when categorizing complex renal cystic masses according to the Bosniak classification. Material and Methods From February 2011 to June 2012, 46 complex renal cysts were prospectively evaluated by three readers. Each mass was categorized according to the Bosniak classification and CT was chosen as gold standard. Kappa was calculated for diagnostic accuracy and data was compared with pathological results. Results CT images found 27 BII, six BIIF, seven BIII, and six BIV. Forty-three cysts could be characterized by CEUS, 79% were in agreement with CT (κ = 0.86). Five BII lesions were upgraded to BIIF and four lesions were categorized lower with CEUS. Forty-one lesions were examined with MR; 78% were in agreement with CT (κ = 0.91). Three BII lesions were upgraded to BIIF and six lesions were categorized one category lower. Pathologic correlation in six lesions revealed four malignant and two benign lesions. Conclusion CEUS and MR both up- and downgraded renal cysts compared to CT, and until these non-radiation modalities have been refined and adjusted, CT should remain the gold standard of the Bosniak classification.

How should patients with cystine stone disease be evaluated and treated in the twenty-first century?

Cystinuria continues to be one of the most challenging stone diseases. During the latest decades our knowledge of the molecular basis of cystinuria has expanded. Today 160 different mutations in the SLC3A1 gene and 116 in the SLC7A9 gene are listed. The full implications of type A, B or AB status are not yet fully understood but may have implications for prognosis, management and treatment. Despite better understanding of the molecular basis of cystinuria the principles of recurrence prevention have remained essentially the same through decades. No curative treatment of cystinuria exists, and patients will have a life long risk of stone formation, repeated surgery, impaired renal function and quality of life. Therapy to reduce stone formation is directed towards lowering urine cystine concentration and increasing cystine solubility. Different molecules that could play a role in promoting nucleation and have a modulating effect on cystine solubility may represent new targets for cystinuria research. Investigation of newer thiol-containing drugs with fewer adverse effects is also warranted. Determining cystine capacity may be an effective tool to monitor the individual patient’s response. Compliance in cystinuric patients concerning both dietary and pharmacological intervention is poor. Frequent clinical follow-up visits in dedicated centres seem to improve compliance. Cystinuric patients should be managed in dedicated centres offering the complete range of minimal invasive treatment modalities, enabling a personalized treatment approach in order to reduce risk and morbidity of multiple procedures.

Pathophysiological aspects of ureterorenoscopic management of upper urinary tract calculi.

Purpose of review Indications for ureterorenoscopy are expanding without hard scientific evidence to support its efficacy. Therefore, it is extremely important to focus on potential harmful effects of the procedure itself. This review explores how physiology of the upper urinary tract reacts to ureterorenoscopy, potentially translating into harmful effects, and how such pathophysiological processes may be minimized. Recent findings Complications to ureterorenoscopy and postoperative pain seem to be related to intrarenal pressure and/or access. Mean intrarenal pressures in the range of 60–100 mmHg during ureterorenoscopy without access sheaths have been measured, thus by far exceeding the threshold for intrarenal backflow, potentially resulting in septic complications. Intrarenal pressure may be reduced by use of ureteral access sheaths, which, however, may cause ureteral damage due to the limited size of the ureter and strain-induced ureteral contractions (peristalsis). Different receptor types modulate this peristaltic activity. &bgr;-receptor agonists have been investigated in animal and human trials for the purpose of relaxing the ureter. In randomized, placebo-controlled trials in pigs and humans, usage of the &bgr;-receptor agonist isoproterenol in the irrigation fluid has shown a potential for reducing both intrarenal pressure and ureteral tone during ureterorenoscopy. Summary Upper urinary tract physiology has unique features that may be pushed into pathophysiological processes by the unique elements of ureterorenoscopy: access and irrigation. Pharmacological ureteral relaxation during ureterorenoscopy deserves further attention with regard to reducing complications and postoperative pain.

Bosniak classification system: inter-observer and intra-observer agreement among experienced uroradiologists

Background The Bosniak classification is a diagnostic tool for the differentiation of cystic changes in the kidney. The process of categorizing renal cysts may be challenging, involving a series of decisions that may affect the final diagnosis and clinical outcome such as surgical management. Purpose To investigate the inter- and intra-observer agreement among experienced uroradiologists when categorizing complex renal cysts according to the Bosniak classification. Material and Methods The original categories of 100 cystic renal masses were chosen as “Gold Standard” (GS), established in consensus by two experienced uroradiologists. Three experienced uroradiological readers were blinded from the previous CT reports. Weighted κ was calculated to assess agreement, defined as: fair, 0.21–0.40; moderate, 0.41–0.60; good, 0.61–0.80; and very good, 0.81–1.00. Results For readers the distribution of correctly classified lesions were as follows: BI, 95–100%; BII, 59–93%; BIIF, 54–92%; BIII, 58–95%; and B IV, 77–100% for the first review. Weighted κ for inter-observer/intra-observer variation was for Reader A: 0.85/0.99, Reader B: 0.97/0.99, and Reader C: 0.98/0.99, (P ≤ 0.001). Conclusion According to the calculated weighted κ all readers performed “very good” for both inter-observer and intra-observer variation. Most variation was seen in cysts catagorized as Bosniak II, IIF, and III. These results show that radiologists who evaluate complex renal cysts routinely may apply the Bosniak classification reproducibly.

Retrograde ureteroscopic holmium laser endopyelotomy in a selected population of patients with ureteropelvic junction obstruction

Objective. Significant controversy remains concerning the best way to treat ureteropelvic junction obstruction (UPJO). This study evaluates subjective and objective outcomes of retrograde holmium laser endopyelotomy in a selected population with UPJO. Material and methods. Forty-seven patients with UPJO were referred to retrograde endopyelotomy between April 2004 and March 2007. Patients with a very large pelvis, a high insertion of the ureter, a renal split function below 20% or a long (>2 cm) stenosed ureteropelvic segment, and patients younger than 18 years were not selected for endopyelotomy, but subjected to laparoscopic pyeloplasty. Renal function was estimated on renal diuretic scan before and after surgery with a mean renographic follow-up of 35 weeks. Subjective results were based on questionnaires which were returned from 44 patients with primary (n=37) or secondary (n=7) obstruction (mean follow-up 110 weeks). Success criteria were defined as symptom relief and improved or preserved renal function. Results. Twenty-nine patients (66%) experienced complete symptom resolution and 10 patients (23%) had significant symptom improvement (i.e. no need for pain-killing medication). Five patients (11%) had unchanged symptoms. No difference in postoperative renal function was observed between these three groups of patients. The differences between preoperative and postoperative renal function were non-significant in each group. No major complications were observed. Five patients (11%) were referred to retreatment owing to unchanged symptoms. Conclusion. Retrograde ureteroscopic endopyelotomy is a safe and effective treatment option in patients with primary and secondary UPJO when selected properly.

Internal Structure of Kidney Calculi as a Predictor for Shockwave Lithotripsy Success

INTRODUCTION The internal structure of renal calculi can be determined on CT using bone windows and may be classified as homogeneous or inhomogeneous with void regions. In vitro studies have shown homogeneous stones to be less responsive to extracorporeal shockwave lithotripsy (SWL). The objective was to evaluate whether the internal morphology of calculi defined by CT bone window influences SWL outcome in vivo. MATERIALS AND METHODS One hundred eleven patients with solitary renal calculi treated with SWL were included. Treatment data were registered prospectively and follow-up data were collected retrospectively. All patients had noncontrast computed tomography (NCCT) performed before SWL and at 3-month follow-up. The stones were categorized as homogeneous or inhomogeneous. At follow-up, the patients stone status was registered. Stone-free status was defined as no evidence of calculi on NCCT. Treatment was considered successful if the patient was either stone free or had clinically insignificant residual fragments. RESULTS Using simple logistic regression, the odds for being stone free 3 months post-SWL were significantly reduced in the patients with inhomogeneous stones compared with patients with homogeneous stones (odds ratio 0.43 [95% confidence interval 0.20, 0.92; p < 0.05]). However, when adjusting for stone size by multiple logistic regression, including stone size (area) as a covariate, this difference became insignificant. CONCLUSION The internal structure of kidney stones did not predict the outcome of SWL in vivo.

Somatosensory and trophic findings in the referred pain area in patients with kidney stone disease

Abstract Background and purpose Visceral and somatic afferents activate the same neuronal structures in the central nervous system. Assessing somatosensory function and trophic changes in the referred pain area may therefore indirectly increase information on mechanisms involved in painful visceral diseases. The aim of this study was to evaluate the sensory and trophic changes in the flank corresponding to the referred pain area in patients with kidney stone disease. Methods A total of 24 patients with unilateral pain-causing kidney stone disease were studied before and after endoscopic percutaneous kidney stone surgery. Trophic changes and sensitivity on the affected and on the contra-lateral side in the pain free period were investigated. For this purpose we used standardized experimental sensory testing including pressure stimulation and electrical (single and repeated) skin stimulation. Five repeated stimuli were used to investigate temporal summation (increased responses to repeated stimuli). To investigate trophic changes ultrasound as well as CT-scan was used, since the latter is considered more precise for exact tissue layer measurements. Results The pain tolerance thresholds to pressure and pain thresholds to electrical stimulation were not significantly different on the two sides (all P>0.1). After surgery no significant alterations in sensitivity were detected, but there was a tendency to higher pain thresholds to electrical stimuli on the affected side (single stimuli P=0.06; repeated stimuli P=0.09). No trophic changes were observed (all P>0.3), and there were no relations between the pain thresholds or trophic findings and the number of colics (all P >0.08). Conclusion In patients with unilateral pain-causing kidney stone disease the pain to experimental pressure and electrical stimuli were comparable on the affected and contra-lateral side. For the first time a CT-scan was used to evaluate tissue thickness in the referred pain area. No trophic changes were seen in the muscle or subcutaneous tissue at the affected side, and there were no correlations between the pain thresholds or trophic findings and the patients history of number of colics. After the operation no significant alterations in sensitivity were detected. Implications This study could not confirm previous studies showing referred hyperalgesia in the skin and trophic changes in the referred pain area to painful visceral disease. Differences in the pain intensity/duration between different diseases and hence the corresponding central neuronal changes may explain the negative findings in the present study.

The challenges of cystinuria in the twenty-first century: a mini review

The challenges of cystinuria in the twenty-first century – a mini review Louise F. Øbro1, Katja V. Pedersen2, Søren K. Lildal1, Susanne S. Osther1, Helene U. Jung1, Kim H. Andreassen1 and Palle J. S. Osther1 1Department of Urology, Urological Research Center, Lillebaelt Hospital, University of Southern Denmark, Fredericia, Denmark 2Department of Clinical Genetics, Lillebaelt Hospital, University of Southern Denmark, Vejle, Denmark

Imaging in Percutaneous Nephrolithotomy

With regard to patient selection for PNL, planning of percutaneous access, intraoperative guidance and postoperative evaluation of potential complications and stone-free status, imaging plays a crucial role. In this chapter the role of current imaging modalities is discussed, and focus is made on how appropriate imaging studies may lead to safe and efficacious percutaneous renal surgery. The role of the various preoperative, intraoperative and postoperative imaging tools is discussed. Furthermore, possible future scenarios with regard to imaging in PNL are briefly touched.