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Samuel C Kim

Publications and source records attributed to Samuel C Kim.

34 records · Page 2Linked to original sources
PubMed2004

Nondestructive analysis of urinary calculi using micro computed tomography.

BACKGROUND: Micro computed tomography (micro CT) has been shown to provide exceptionally high quality imaging of the fine structural detail within urinary calculi. We tested the idea that micro CT might also be used to identify the mineral composition of urinary stones non-destructively. METHODS: Micro CT x-ray attenuation values were measured for mineral that was positively identified by infrared microspectroscopy (FT-IR). To do this, human urinary stones were sectioned with a diamond wire saw. The cut surface was explored by FT-IR and regions of pure mineral were evaluated by micro CT to correlate x-ray attenuation values with mineral content. Additionally, intact stones were imaged with micro CT to visualize internal morphology and map the distribution of specific mineral components in 3-D. RESULTS: Micro CT images taken just beneath the cut surface of urinary stones showed excellent resolution of structural detail that could be correlated with structure visible in the optical image mode of FT-IR. Regions of pure mineral were not difficult to find by FT-IR for most stones and such regions could be localized on micro CT images of the cut surface. This was not true, however, for two brushite stones tested; in these, brushite was closely intermixed with calcium oxalate. Micro CT x-ray attenuation values were collected for six minerals that could be found in regions that appeared to be pure, including uric acid (3515 - 4995 micro CT attenuation units, AU), struvite (7242 - 7969 AU), cystine (8619 - 9921 AU), calcium oxalate dihydrate (13815 - 15797 AU), calcium oxalate monohydrate (16297 - 18449 AU), and hydroxyapatite (21144 - 23121 AU). These AU values did not overlap. Analysis of intact stones showed excellent resolution of structural detail and could discriminate multiple mineral types within heterogeneous stones. CONCLUSIONS: Micro CT gives excellent structural detail of urinary stones, and these results demonstrate the feasibility of identifying and localizing most of the common mineral types found in urinary calculi using laboratory CT.

Calcium Phosphates↗
PubMed2004

Helical computed tomography accurately reports urinary stone composition using attenuation values: in vitro verification using high-resolution micro-computed tomography calibrated to fourier transform infrared microspectroscopy.

OBJECTIVES: To assess the ability of helical computed tomography (CT) to differentiate regions of known mineral composition in typical, heterogeneous urinary stones. Interest is substantial in the urologic community in using radiologic imaging to determine accurately the composition of urinary calculi. Recent advances in CT make this a viable prospect, but the heterogeneity of most stones is a complicating factor. METHODS: The ability of micro-CT (a high-resolution laboratory instrument) to identify the mineral composition of stones was confirmed by calibrating micro-CT attenuation values to pure mineral regions of sliced stones using infrared microspectroscopy. Intact human urinary stones were then analyzed by micro-CT, and regions-of-interest of pure mineral were correlated with identical regions-of-interest from quad slice multi-detector row helical CT images. With helical CT, narrow slice widths were used to decrease volume-averaging errors, and bone windows were used so that internal stone structure was visible. RESULTS: When stones were imaged using helical CT at narrow slice widths, mineral-specific regions-of-interest yielded nonoverlapping attenuation values for uric acid (566 to 632 Hounsfield units [HU]), struvite (862 to 944 HU), calcium oxalate (1416 to 1938 HU), and hydroxyapatite (2150 to 2461 HU). CONCLUSIONS: High resolution helical CT yields unique attenuation values for common types of stone mineral, but proper windowing is required to localize regions of homogeneity. The results of this in vitro study suggest that high-resolution helical CT may be able to identify stone composition at patient diagnosis.

Calcium Oxalate↗
PubMed2004

Efficacy and safety of the Healthtronics LithoTron lithotripter.

PURPOSE: To evaluate our experience with the LithoTron lithotripter (Healthtronics, Atlanta, GA), a dry portable system that utilizes a spark-gap electrode as an energy source. PATIENTS AND METHODS: We prospectively evaluated the first 312 treatments performed on 199 men and 99 women with an average age of 43.5 years (range 4 months-80 years), over a 25-month period between May 1999 and June 2001. Of the 468 stones treated, 136 were located in the ureter, 52 in the renal pelvis or ureteropelvic junction, and 230 in the kidney; the sites of 50 were not specified in our database. The average stone size was 8.0 mm (range 1-40 mm). Follow-up included a plain (KUB) film, CT scan, or intravenous urogram (IVU) and was available for 256 patients. "Stone free" was defined as no fragments visible on postoperative images. The mean radiographic follow-up was 74 days (range 0-866 days). Data collection was initially done manually by data sheets, but a Web-based medical database application was developed in order to enter, store, retrieve, and analyze the data more efficiently. RESULTS: The average number of shocks delivered per renal unit was 2689 at 25.8 kV. Seventy-five percent of the procedures were performed with intravenous sedation. Two thirds (169/256) of the patients were rendered stone free with one treatment. According to size, 71% (209/294) of stones <1 cm, 57% (39/68) of stones between 1.0 and 1.5 cm, and 22% (8/36) of stones >1.5 cm were eliminated. There were 23 patients who required further treatment; from the available data, 18 of them are currently stone free. Perioperative complications occurred in 6 patients (2%). No patient had worsening renal function or new-onset hypertension. The effectiveness quotient was 59.3%. CONCLUSION: The LithoTron lithotripter is satisfactory for stones <1 cm.

Adolescent↗
PubMed2004

Progress in the use of helical CT for imaging urinary calculi.

Helical CT has become the preferred method to diagnose urinary calculi in patients presenting with abdominal or flank pain. Recent in vitro studies have shown that CT also can display the internal structure in stones with remarkable detail. Because some stones respond better to SWL than others, knowing stone structure at diagnosis could be helpful in choosing among treatment options. This paper examines the potential for CT to be used in this way. Older CT technology proved to be problematic, in that all studies using low-resolution CT will suffer from an artifact in which stone size affects apparent CT attenuation values. Thus, the observation that stones with low measured CT attenuation break more easily than stones with high attenuation could be attributable entirely to an artifact of stone size. Most stones are composed of more than one mineral, and heterogeneity of composition may contribute to variability in stone response to SWL. Older technology is not useful in evaluating stone composition, but current and emerging CT machines have sufficient resolution to determine the composition and structure of stones inside the patient, provided proper viewing windows are used. Continuing improvement in image resolution in helical CT promises to provide information about stone composition and structure that will ultimately lead to better care for patients with stone disease.

Artifacts↗
PubMed2004

Simultaneous holmium laser enucleation of prostate and upper-tract endourologic stone procedures.

BACKGROUND AND PURPOSE: The holmium laser is a versatile urologic tool. Its unique cutting and coagulating properties allow multiple procedures, such as stone fragmentation and laser enucleation of the prostate (HoLEP), to be performed with a single set-up. This paper reviews our experience with simultaneous HoLEP and endourologic upper-tract stone procedures. PATIENTS AND METHODS: We retrospectively reviewed all 11 patients (12 renal units) treated with the combined approach of HoLEP and an upper-tract endourologic procedure for stone disease. All patients initially underwent HoLEP, followed immediately by percutaneous nephrolithotomy (PCNL)(N=2), ureteroscopy (URS)(N=8), or both (N=1). The mean stone diameter was 34.7 mm for PCNL and 6.7 mm for URS. Outcome data and complications were recorded. RESULTS: The mean preoperative and postoperative American Urological Association Symptom Scores were 21.8 and 6.3, respectively. The mean prostatic specimen weight was 118 g (range 21-376 g), and the mean hospital stay was 1.4 days. For 10 patients with available prostatic specific antigen (PSA) data, the mean preoperative and postoperative values were 6.2 and 0.9 ng/mL, respectively. All patients were catheter free at discharge. All three PCNL patients were rendered stone free; all four URS patients who had radiographic follow-up were stone free. There were no short- or long-term complications, and no transfusions were necessary. CONCLUSIONS: Simultaneous HoLEP and laser lithotripsy are feasible, emphasizing the unique capabilities of the holmium laser. The hemostasis offered by HoLEP allows safe removal of prostatic tissue and urinary calculi, obviating multiple procedures.

Aged↗
PubMed2003

Holmium Laser Enucleation of the Prostate (HoLEP): A Technical Update.

INTRODUCTION: Holmium laser enucleation of the prostate (HoLEP) combined with mechanical morcellation represents the latest refinement of holmium:YAG surgical treatment for benign prostatic hyperplasia (BPH). Utilizing this technique, even the largest of glands can be effectively treated with minimal morbidity. The learning curve remains an obstacle, preventing more widespread adoption of this procedure. This paper provides an outline of the HoLEP technique as is currently used at two centers in hopes of easing the initial learning curve. TECHNICAL CONSIDERATIONS: Detailed descriptions of the major steps of the HoLEP procedure are provided with attention to critical steps such as identification of the surgical capsule, median and lateral lobe enucleation, and morcellation of enucleated tissue. CONCLUSIONS: HoLEP is a promising alternative for the surgical treatment of BPH which allows complete removal of intact lobes of the prostate. Obstruction is relieved immediately with superior hemostasis, no risk of TUR syndrome, and a minimal hospital stay.

Journal Article↗
PubMed2003

Shockwave lithotripsy: anecdotes and insights.

Shockwave lithotripters have evolved considerably since the introduction of the Dornier HM3 machine 20 years ago. Although shockwave lithotripsy (SWL) remains the preferred treatment for the majority of symptomatic upper urinary-tract calculi, newer lithotripters are not as effective and may have a higher risk of side effects. Lack of progress in lithotripter evolution is attributable to inadequate understanding of how and why shockwaves produce effects on stone and tissue. Current knowledge suggests that stones fragment by the mechanisms of compression fracture, spallation, squeezing, and acoustic cavitation, while tissue damage from shockwaves is secondary to cavitation and non-cavitational forces such as sheer stress. It appears likely that most tissue damage from shockwaves is caused by cavitation. As the understanding of SWL matures, new lithotripter designs may emerge that truly represent an improvement on the original Dornier HM3 machine.

Anesthesia↗
PubMed2003

Percutaneous nephrolithotomy: an update.

PURPOSE OF REVIEW: Percutaneous nephrolithotomy has undergone an evolution in technique and in equipment since its introduction in the late 1970s. This evolution continues today and is evidenced by the numerous publications about the technique. This review summarizes some of the important articles over the past year. RECENT FINDINGS: Although ureteroscopy and shock wave lithotripsy predominate in the treatment of urolithiasis, percutaneous nephrolithotomy continues to play an important role. Percutaneous nephrolithotomy is advantageous as it causes minimal renal injury and maximizes stone clearance, especially in patients with complex stone disease. Although nephrostomy drainage tubes have always been placed after percutaneous nephrolithotomy, there may be specific indications for tubeless percutaneous nephrolithotomy. SUMMARY: Percutaneous nephrolithotomy continues to be an important part of the urologist's armamentarium. Recent studies have redefined the role of percutaneous nephrolithotomy and future studies will further delineate the importance of this procedure in the treatment of urolithiasis.

Clinical Trials as Topic↗
PubMed2003

The PIC cystogram: a novel approach to identify "occult" vesicoureteral reflux in children with febrile urinary tract infections.

PURPOSE: When the standard cystogram does not show vesicoureteral reflux in children who have experienced febrile urinary tract infections (UTIs), clinical management is controversial. We postulated that vesicoureteral reflux accounts for such UTIs but is "occult." We tested this hypothesis by using a novel method, PIC cystography (Positioning the Instillation of Contrast at the ureteral orifice) at the time of cystoscopy. MATERIALS AND METHODS: We performed PIC cystography with instillation of contrast medium at the ureteral orifice consecutively and prospectively in 57 children who underwent cystoscopy between November 1999 and February 2002 to evaluate febrile UTIs in 40 patients, dysfunctional voiding in 14 and hydronephrosis in 3. The control group (27 patients, 54 renal units) was used to assess the accuracy of PIC by comparing the results against those with the standard cystogram in children who did not have febrile infection and did not demonstrate vesicoureteral reflux (15 patients, 30 renal units), and in those who had febrile infection and vesicoureteral reflux (12 patients, 24 renal units). The study group (30 patients, 60 renal units) served to assess the incidence of "occult" vesicoureteral reflux in children who experienced febrile UTIs yet did not have vesicoureteral reflux on standard cystography. RESULTS CONTROL GROUP: In children without febrile UTIs all 30 ureteral orifices had a normal endoscopic appearance and no vesicoureteral reflux by PIC cystography. In children with febrile UTIs 15 ureteral orifices with known vesicoureteral reflux were lateral and/or patulous and demonstrated vesicoureteral reflux by PIC, 4 appeared normal and did not exhibit vesicoureteral reflux on standard cystography or by PIC, and 5 were lateral and/or patulous in appearance and did not display vesicoureteral reflux on standard cystography, but did show vesicoureteral reflux by PIC. These findings reveal that PIC cystography is 100% sensitive at demonstrating reflux already known by standard cystogram, is 87% specific as it showed reflux in 5 of 39 renal units not revealed by a standard cystogram and has an overall accuracy of 91%. STUDY GROUP: At cystoscopy all 30 children demonstrated an abnormal appearance of one or both ureteral orifices. PIC cystography showed vesicoureteral reflux in all 30 children (48 renal units, 12 unilateral and 18 bilateral). The remaining ureteral orifices (12), which appeared normal, did not permit vesicoureteral reflux. Children with vesicoureteral reflux by PIC were treated with antimicrobial prophylaxis (26) or ureteral reimplantation (4, 2 unilateral and 2 bilateral reimplantation) Postoperatively, these children did not experience a febrile UTI during followup (average 8 months). CONCLUSIONS: PIC cystography is simple to perform using routinely available operating room equipment and does not artifactually induce vesicoureteral reflux. The incidence of "occult" vesicoureteral reflux in children who experience febrile UTIs without vesicoureteral reflux on standard cystography is 100% by PIC cystography. PIC cystography should be done when vesicoureteral reflux is suspected in children who experience febrile UTIs but do not exhibit reflux on standard cystography.

Adolescent↗
PubMed2003

Holmium laser enucleation of prostate (HoLEP): the Methodist Hospital experience with greater than 75 gram enucleations.

PURPOSE: Holmium laser enucleation of the prostate (HoLEP) effectively removes obstructive prostate tissue in minimally invasive fashion. We present our large enucleation outcomes (greater than 75 gm retrieved). We examined post-procedural prostate specific antigen (PSA) and transrectal ultrasound (TRUS) volume changes to assess tissue removal completeness. MATERIALS AND METHODS: We retrospectively reviewed HoLEPs performed from April 1, 1999 through September 30, 2002 to identify all enucleations greater than 75 gm. Demographic, laboratory, operative and pathological data were obtained. Patients were surveyed to document longer term complications. RESULTS: The cohort of 108 patients had a mean age and specimen weight of 71.5 years (range 53 to 90) and 120.6 gm (range 75.3 to 376), respectively. Average procedural time and hospital stay were 166.8 minutes (range 75 to 473) and 1.2 days (range 0 to 4), respectively. No deaths or episodes of transurethral resection syndrome occurred. Postoperative complications included transfusion in 2 cases, a clot retention episode in 3, capsular perforation in 2, morcellator blade malfunction in 4, minor bladder mucosal injury in 1 and bladder neck contracture in 1. American Urological Association symptom scores reassessed in 53 patients without chronic retention an average +/- SD of 10.6 +/- 7.1 months postoperatively showed a mean decrease from 20.3 +/- 6.4 to 4.7 +/- 3.8. PSA in 48 patients a mean of 5.0 +/- 4.1 months postoperatively had decreased an average of 91.7%. In 10 patients TRUS data revealed a mean post-procedural volume decrease of 85.9%. CONCLUSIONS: HoLEP can be performed on extremely large prostates with minimal risk or need for secondary interventions. Most patients are discharged home after an overnight stay. Postoperative decreases in PSA and TRUS volumes support the completeness of enucleation that can be achieved.

Adenocarcinoma↗
PubMed2003

Laparoscopic renal cryosurgery: the Northwestern experience.

PURPOSE: Laparoscopic renal cryosurgery provides a minimally invasive alternative for the treatment of small renal lesions of undefined malignant potential. We report on our series of patients treated with laparoscopic renal cryosurgery. MATERIALS AND METHODS: Fifteen patients underwent laparoscopic renal cryoablation of peripheral, exophytic unifocal renal lesions. Patients were managed with a 4-port transperitoneal approach for anteromedial tumors and 3 to 4-port retroperitoneal approach for posterolateral tumors. All lesions were biopsied and sent to pathology for permanent section. A 4.8 mm cryoprobe (CMS cryoprobe, 4.8 mm x 2 cm x 40 cm, Cryomedical Sciences Inc., Ewing, New Jersey) was placed into the tumor using visual and ultrasonographic guidance, and a double freeze-passive thaw cycle was performed. The iceball was extended at least 1 cm beyond the tumor margin under ultrasound guidance. Followup biopsies were performed on all consenting patients with renal cell carcinoma at least 3 months after cryosurgery was performed. RESULTS: Laparoscopic renal cryosurgery was successfully performed on all 15 patients (6 male and 9 female). Of the 15 patients 10 had renal cell carcinoma. Mean age was 68.5 years (range 49 to 86). Mean tumor size was 2.15 cm (range 1.2 to 3.2) and mean estimated blood loss was 67 cc (range 15 to 125). There were 2 perioperative complications. Mean hospital stay was 3.5 days (range 1 to 11). Patients returned to work after 16.5 days (range 7 to 28). Radiographic followup revealed stable cryoablative lesions in all patients. Mean radiographic followup was 453 days (range 147 to 816). Mean preoperative creatinine was 1.25 mg/dl (range 0.8 to 4.3) and mean postoperative creatinine obtained 1 month postoperatively was 1.36 (range 0.8 to 4.8). There was 1 treatment failure, although another patient had a positive biopsy outside the ablated area. The failure occurred in the largest tumor treated (3.2 cm) and was due to incomplete treatment of the periphery of the lesion. The other patient had a successfully treated tumor but a positive followup biopsy due to multifocal papillary renal cell carcinoma and required nephrectomy. CONCLUSIONS: Laparoscopic renal cryosurgery appears to be a safe and effective minimally invasive alternative for the treatment of small renal masses. Careful selection of patients with lesions that are less than 3.0 cm and close monitoring of the iceball is necessary to treat these patients successfully.

Aged↗
PubMed2003

Endoscopic renal papillary biopsies: a tissue retrieval technique for histological studies in patients with nephrolithiasis.

PURPOSE: The mechanisms behind calcium nephrolithiasis remain unclear. Previous research has relied on animal models or cell lines, yielding limited insight into the pathophysiology of human calcium stone disease. To determine changes occurring in the human kidney during active stone disease we used an endoscopic renal papillary biopsy protocol in calcium stone formers undergoing percutaneous nephrolithotomy. MATERIALS AND METHODS: Following stone burden clearance via percutaneous nephrolithotomy 15 idiopathic calcium oxalate and 4 ileal bypass stone formers underwent flexible and rigid nephroscopy. Biopsies from select papillae in the peripheral and interpolar regions were obtained with 5Fr flexible cup biopsy forceps. A papilla adjacent to the accessed calix was biopsied with 10Fr cup biopsy forceps. Cortical biopsies along the access tract were also obtained with the 10Fr forceps. RESULTS: All patients had successful biopsy completion. No complications were attributable to the biopsy process and no blood transfusions were required. Of the 19 patients 12 were contacted for followup at a mean of 21.7 +/- 9.0 months with none experiencing adverse sequelae such as bleeding or significant pain. A total of 14 patients had followup serum creatinine available showing that the difference in mean preoperative and postoperative values was not clinically significant (1.00 +/- 0.27 and 1.11 +/- 0.27 mg/dl, respectively). The quality of biopsied tissue permitted accurate immunohistochemical staining of crystal deposits and mineral analysis. CONCLUSIONS: Endoscopic papillary biopsies were performed safely in a small patient population. Tissue obtained using this protocol can be used for detailed histological and analytical studies, which may lead to significant advances in our understanding of stone formation mechanisms.

Biopsy↗
PubMed2002

Extracorporeal shock wave lithotripsy of pancreatic duct stones using the Healthtronics LithoTron lithotriptor and the Dornier HM3 lithotripsy machine.

PURPOSE: Pancreatic duct stones, which are most often a result of alcohol induced chronic pancreatitis, can lead to chronic abdominal pain, pseudocysts, and exocrine and endocrine failure of the pancreas. Others have reported success using extracorporeal shock wave lithotripsy (ESWL) (Dornier Medical Systems, Inc., Marietta, Georgia) for pancreatic stones. We report our experience with pancreatic ESWL using the LithoTron (Healthtronics, Marietta, Georgia) and HM3 (Dornier) lithotripsy machines. MATERIALS AND METHODS: We performed pancreatic ESWL in 23 patients in 4 years, including in 12 with the LithoTron and in 11 with the HM3. After ESWL endoscopic retrograde cholangio-pancreatography (ERCP) was performed in all cases. Stone-free status was defined as no stone fragments visualized or the elimination of all post-ESWL stones by ERCP. RESULTS: Stone-free status was documented in 83% and 82% of patients treated with the LithoTron and HM3, respectively, and 2 per group later required open surgical intervention. There were no changes in pancreatic enzymes and no cases of sepsis or fever after ERCP. CONCLUSIONS: In association with post-procedure ERCP pancreatic ESWL is an effective and safe procedure that enables patients with obstructing pancreatic duct stones recalcitrant to primary endoscopic extraction to avoid a potentially morbid open procedure. The HM3 and LithoTron have comparable efficacy and safety. This modality is particularly effective for a stone aggregate of less than 20 mm., while a larger stone burden of greater than 20 mm. in aggregate and multiple stones are clear risk factors for treatment failure.

Adult↗
PubMed2002

Percutaneous hepatolithotomy: the Northwestern University experience.

Obstruction of intrahepatic ducts by calculi can lead to abdominal pain, cholestasis, abscesses, and cholangitis. Patients with stones recalcitrant to extraction using endoscopic retrograde cholangiopancreatography (ERCP) have traditionally been referred to a general surgeon for open stone extraction or hepatic lobectomy despite its great potential morbidity. Borrowing techniques, instrumentation, and experience in performing percutaneous nephrolithotomy, we describe our experience with percutaneous hepatolithotomy (PHL), a minimally invasive, safe, and effective alternative to open surgery for recalcitrant biliary stones.

Adult↗
PubMedDate not supplied

Urolithiasis associated with topiramate.

OBJECTIVE: Topiramate is a sulfamate-substituted monosaccharide anticonvulsant used as adjunctive therapy for intractable refractory seizures. It is report a case of topiramate-induced urolithiasis. CASE REPORT: A 35-year-old man presented with acute, right-sided, colicky flank pain. He denied hematuria or dysuria. He was in use of phenytoin, risperidone, phenobarbital, and topiramate. The total daily dose of topiramate was 375 mg. A CT scan showed a 7 x 1 mm curvilinear density at the right ureterovesical junction with proximal hydrouretronephrosis. He was managed with rigid ureteroscopic stone extraction and the calculus metabolic analysis revealed the stone was composed of carbonate apatite (70%), calcium oxalate dihydrate (20%), and calcium oxalate monohydrate (10%). COMMENTS: The present case typifies many features of topiramate-induced urolithiasis. Those who care for patients with urinary stone disease should be aware of this association.

Abdominal Pain↗