IMGING GUIDANCE IN PCNL. Mohammad Hossein Soltani MD Assistant professor of urology Fellowship of endourology

Transcription

1 IN THE NAME OF GOD

2 IMGING GUIDANCE IN PCNL Mohammad Hossein Soltani MD Assistant professor of urology Fellowship of endourology

3 Ultrasonographic guidance Real time diagnostic ultrasonography (US) has been widely accepted as the imaging guidance for a dilated renal collecting system. The overall success rate is 88 99%. The complication rate is 4 8% and depends on the indications. Ultrasound is radiation free, effective, and rapid, and is possible with a portable machine causing minimal complications in experienced hands. The important anatomical landmarks during sonographic examination are renal capsule, renal cortex (low level homogenous echoes), renal medulla (sonolucent structure), and hydronephrosis (hypoechoic cavity surrounded by a central echo complex).

4 The primary advantages of ultrasonographic guidance are as follows: Minimizes radiation exposure for patients and operating personnel Imaging of structures between skin and kidney; the depth of access needle and the anatomy around kidney can be evaluated by ultrasound. This technique can prevent adjacent and visceral organ injury No need of contrast media, especially for patients with azotemia Avoids intrarenal vascular injury (color Doppler ultrasound) Overcomes the problem of unsuccessful retrograde ureteral catheterization that is required for contrast media injection in fluoroscopic guidance Safe for patients, especially pregnant and pediatric patients The procedure can be performed in supine position.

5 The disadvantages of ultrasonographic guidance are: Sonographic identification of the needle needs operator skill but successful puncture of the collecting system can be confirmed by the appearance of urine following removal of the needle obturator Technical difficulty in percutaneous access of non or mild hydronephrosis; this can be overcome by administration of diuretic which transiently dilates the calyces Inability to clearly visualize and manipulate a guide wire following renal access.

6 Basiri et al. presented the technique of totally US guided PCNL in 30 patients under flank position. This technique provided satisfactory outcomes without any major complications. (2008) Soltani et al presented the technique of totally US guided PCNL in 10 pediatric patients less than 10 years old under prone position (2015)

7 Chin Med J. 2014;127(24): Complication and safety of ultrasound guided percutaneous nephrolithotomy in 8,025 cases in China. From September 2004 to August 2013, cases, males (54.8%) and females (45.2%), whose age ranged from 6 months to 85 years old, with upper urinary tract stones, underwent PCNL. RESULTS: All procedures were successful., and 2 patients lost the diseased kidney due to refractory bleeding in the early stage of the PCNL. Ninety four (1.2%) patients received blood transfusions and 20 (0.25%) patients needed highly selective renal artery embolization. Fifteen (0.19%) patients had a pleural injury (68%) cases were completed by a single tract and (32%) cases added more tracts. The mean stone size (longest diameter) was 2.8 cm (range 1.2 to 26.5 cm). The final stone free rate was 85.5%. CONCLUSIONS: X ray free Doppler ultrasound guided percutaneous nephrolithotomy is feasible and safe in a variety of cases of renal and/or upper ureteral stones. The morbidity from major complications was reduced remarkably after special training. It is worthy of wider use compared with fluoroscopy in patients with special kidneys (e.g. solitary kidney, spinal deformity, ectopic kidney) and in infants.

8 A comparative study of clinical value of single B mode ultrasound guidance and B mode combined with color doppler ultrasound guidance in miniinvasive percutaneous nephrolithotomy to decrease hemorrhagic complications. Urology. 2010;76: This study demonstrated color Doppler ultrasound to be more accurate and safer with less blood loss, compared to B mode ultrasound. The advantage of color Doppler ultrasound was further confirmed by a comparative study in miniinvasive percutaneous nephrolithotomy (m PCNL). Compared with the B mode ultrasound group, hemorrhagic complications and blood transfusion rate were significantly less in color Doppler ultrasound group where no major hemorrhagic complications occurred. The incidence of patients requiring blood transfusion, renal arteriovenous fistula and hemorrhage requiring embolization were 2.6, 1.1%, and 1.1%, respectively. The technique of renal access using color Doppler ultrasound is thus very important, especially in patients with a solitary kidney.

9 Percutaneous renal intervention: Comparison of 2 D and time resolved 3 D (4 D) ultrasound for minimal calcyceal dilation using an ultrasound phantom and fluoroscopic control. Ultrasound Med Biol. 2008;34: The advancements in ultrasound technology, 3 D ultrasound (3 DUS) and 4 D ultrasound (4DUS) can be used in clinical practice at the patient's bedside. John et al. compared 2D and 4D guidance for renal access. There was no significant difference in the puncture time (1.8 min for 2 DUS and 2 min for 4 DUS) and no difference in the quality of puncture. 4 DUS had a higher difficulty rating compared to 2 DUS. This advanced technique needs more investigation to prove its efficacy for this indication.

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11 Computed tomography Computed tomography (CT) guidance is another alterative for management of complex cases. This imaging guidance is essential in patients with specific medical conditions such as morbid obesity, splenomegaly, hepatomegaly, severe skeletal anomalies like scoliosis or kyphosis, or who have had previous major intraabdominal surgery, and in patients with minimal or no dilatation of renal pelvis. Cross sectional imaging is needed to facilitate safe access in cases with difficult access to the collecting system, which is usually needed in patients with retrorenal colon, spinal dysraphism, ileal conduits, nephrolithiasis in the presence of angiomyolipomas, and in morbidly obese patients with malrotated kidney.

12 Chalasani et al. studied the position of colon in the prone position by CT Kidney Ureter Bladder (KUB) in 134 patients. The prevalence of retrorenal colon in men was 13.6% on the right and 11.9% on the left, and in women was 13.4% on the right and 26.2% on the left. They suggested preoperative imaging for patients at higher risk of retrorenal colon who should have alternative technique in renal access such as ultrasound and CT guidance. The technique for CT guidance for percutaneous access is similar to the technique of CT guided drainage procedure in patients with urinoma drainage or other perinephric abnormalities.

13 Scand J Urol Jun;48(3): Three-dimensional computed tomography planning improves percutaneous stone surgery. Patients planned for PCNL were included in a prospective study. Decision algorithms were studied and recorded before and after 3D CT planning in a total of 35 patients. RESULTS: Thirty one of the patients (88%) had a complex stone situation. The CT examinations resulted in change of access plan in 15 out of 28 patients, in addition to seven patients where access could not be planned without 3D CT, totalling 22 out of 35 (63%). This resulted in 24 patients (69%) being stone free after a single PCNL session. Of these 24 patients, 22 (22/35 = 63%) were stone free with one dilated access track only. In 16 of the 24 patients (76%) who were stone free after one PCNL procedure, evaluation of the 3D CT images had changed the initial preoperative planning (10 cases) or made planning possible (six cases). A few patients had thoracic complications but there were no cases with bleeding. CONCLUSIONS: Preoperative planning of complex stone situations with 3D CT had a significant impact on operative procedure, resulting in a low number of access punctures.

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16 J Endourol Feb;29(2): The SimPORTAL fluoro-less C-arm trainer: an innovative device for percutaneous kidney access. The SimPORTAL CAT includes a mini C-arm for simulating fluoroscopic imaging and a silicon flank simulation model for needle insertion. The C-arm has two mounted video cameras and is jointed to tilt and rainbow. The flank model contains an anatomically accurate cast of the upper urinary tract, including the ureter, calyces, and the renal pelvis, with an overlay of ribs to visually and tactically simulate the 10th-12th ribs. The simulated fluoroscopic imaging is viewed on a computer screen allowing for real-time visualization. The fluoroscopy-less CAT is an economically feasible and accurate model for training parallax. It effectively replicates the functions of a C-arm X-ray system for percutaneous access to the kidney without any radiation exposure to the learner. Further studies will examine construct validity for training and assessing percutaneous access skills.

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20 Arab J Urol Jun;12(2): Multislice computed tomography vs. intravenous urography for planning supine percutaneous nephrolithotomy: A randomised clinical trial.

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22 RESULTS: The mean (SD) time taken to gain percutaneous access was longer in group 1 than group 2, at 22.2 (1.76) vs (1.62) min (P < 0.001), as were the operative duration, at 81.9 (14.9) vs (7.6) min (P < 0.001), and fluoroscopic time, at 3.5 (1.7) vs. 2.2 (1.3) min (P = 0.002). In group 1 there were four cases (13%) in which there were difficulties in establishing percutaneous access, while in group 2 there were none (P = 0.003). There was intraoperative morbidity in three patients (10%) in group 1 and two (7%) in group 2. CONCLUSION: Multislice CT is a safer, more accurate and noninvasive imaging technique than IVU for mapping the pelvicalyceal system. It saves time and is essential in choosing the optimal percutaneous access into the pelvicalyceal system for a safe and successful PCNL.

23 Fluoroscopy The high quality of current C arm fluoroscopic equipment and the familiarity among urologists of fluoroscopic imaging has led to its preferred use in percutaneous renal access, particularly in the operating room. Surgeons prefer fluoroscopy for guidance due to the clear visibility of the needle and guide wire. For percutaneous renal surgeries such as PCNL or endopyelotomy, fluoroscopic monitoring is very important for the entire procedure during renal access, guide wire manipulation, tract dilatation, residual stone evaluation, and postprocedural nephrostogram. The advantages of fluoroscopic guidance are: Its familiarity to most urologists Its ability to visualize radiopaque calculi Iodinated contrast media can be used to aid in stone localization Demonstrates anatomical details.

24 Radiation safety is one of the major concerns during PCNL under fluoroscopic guidance. The maximum yearly whole body exposure to radiation recommended by the National Council on Radiation Protection is 5 rem. Fluoroscopic screening time (FST) during PCNL is the main factor in radiation exposure. During fluoroscopic guidance in PCNL, the maximum radiation exposure is to the surgeon, especially to the legs and least to the eye, followed by the assistant and nurse. Tepeler et al. reported that large stone and multiple accesses are factors that can affect the FST during PCNL. FST is not affected by body mass index (BMI), stone configuration, degree of hydronephrosis, site of access, and history of open nephrolithotomy. Radiation dose reduction can be achieved by directing the fluoroscopy beam from under the table. The surgeon should wear a lead apron, thyroid shields, leadimpregnated glasses, and lead gloves. Young children are more radiosensitive and radiation exposure has been linked to malignancies, including thyroid cancer and leukemia.

25 Urol J Mar 3;11(1): Ultrasonography combined with fluoroscopy for percutaneous nephrolithotomy: an analysis based on seven years single center experiences. We retrospectively analyzed 562 renal calculi patients (313 men and 249 women; mean age 46 years, ranged from 13 to 70 years) who underwent 582 PCNL from March 2004 to October 2011 in our department. RESULTS: Of participants, 89.6% experienced less than 3 puncture times; 2 patients (0.4%) experienced puncture failures; percentage of single or multiple tracts was 89.7% and 10.3%, respectively, 55 patients (9.5%) needed auxiliary measures after one PCNL (24 second PCNL and 31 extracorporeal shock wave lithotripsy). The mean operative time was 82.3 min (range, min). The stone free rate was 90.5%. Thirty five patients (6.0%) had postoperative fever and responded to antibiotics. Thirteen patients (2.2%) needed blood transfusion. Twelve patients (2.1%) developed septic shock and were given anti shock therapy. Two patients (0.3%) needed angiographic renal embolization or nephrectomy. CONCLUSION: With its high success rate for achieving access to the targeted calyx and high stone clearance rate, the guidance of ultrasonography and fluoroscopy should be the first option in PCNL.

26 MRI guidance MRI guidance has the advantage of no radiation exposure. However, the use of MRI for renal access is limited and development of new technology of MR scanners with faster scanning and better physical access to patients may increase its utility.

27 Eur Radiol May;19(5): MRI guided percutaneous nephrostomy: a feasibility study. The purpose of this study was to assess the feasibility and safety of magnetic resonance imaging (MRI) guided PCN in an open configuration low field MRI system. Eight patients were prospectively enrolled in the study. The degree of the dilatation of the renal collecting system varied from minimal to severe. All procedures were performed solely under MRI guidance with a 0.23 T open configuration C arm shaped MRI system with interventional optical tracking. In each case, PCN was performed with a MRI compatible drainage kit using the Seldinger technique. Seven out of eight nephrostomies were successfully performed under MRI guidance. No major complications occurred during the procedure or follow up. MRI guided PCN in dilated renal collection system is feasible and safe. The presented technique has limitations that necessitate further technical developments before the procedure can be applied to nondilated kidneys and recommended for routine clinical use.

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