Radiation exposure to patients and personnel during interventional ERCP at a teaching institution

BACKGROUND

This study was designed to determine the radiation dose to patients and personnel during ERCP procedures.

METHODS

Phantom studies were performed to compare dosimetry for two image capture systems and to determine the effectiveness of shielding in reducing stray radiation. Radiation techniques and dosimetry were recorded in 72 patients undergoing ERCP.

RESULTS

Phantom studies indicated that increasing fluoroscopy voltage from 75 to 96 kV decreased entrance dose by 50%. Image capture by digital radiography decreased radiation exposure by 66%. Shielding decreased stray radiation exposure by 93%. All patients underwent cholangiography (n = 71) and/or pancreatography (n = 53). The mean number of interventional ERCP procedures performed per patient was 1.8 (range, 0 to 6). The mean measured patient entrance dose was 80 mGy (8 R; range, 0.2 to 73 R); however, the calculated mean entrance dose (based on measured intensifying screen doses) may have been as high as 3000 mGy (30 R; range, 0.8 to 300 R). Measured patient exposure increased with fluoroscopy time (r = 0.9) and with the number of interventions performed (r = 0.3). The mean dose to personnel was estimated at 0.04 mR.

CONCLUSIONS

The patient radiation dose depended most on fluoroscopy time. The dose may be lowered by minimizing fluoroscopy time, using higher voltage and lower current for fluoroscopy, and using digital radiography for documentation. Personnel were adequately protected.

Spiral CT angiography of the aorta

Imaging of the aorta and its branches has benefitted greatly from the development of spiral CT techniques, which are relatively fast and noninvasive. The volumetric acquisition of spatial information has permitted the computer to reformat images for inspection of the vessels by several methods from an infinite number of viewing angles. Most aortic diseases-including congenital anomalies, dissection, aneurysm, trauma, inflammation, infection, and thromboembolic disease-can be depicted with this technology. In selected cases, spiral CT may be the only imaging modality needed for the surgical planning of aortic repair. This report discusses the CT angiography technique, its application to a variety of disease states, its role relative to other imaging modalities, and guidelines for patient selection.

Measurement of coronary artery calcium with dual-slice helical CT compared with coronary angiography: evaluation of CT scoring methods, interobserver variations, and reproducibility

OBJECTIVE

This study was performed to evaluate new scoring methods for quantitating coronary artery calcifications with helical CT and to compare the results with those of quantitative coronary angiography in patients with suspected coronary artery disease.

SUBJECTS AND METHODS

Unenhanced dual-slice helical CT and coronary angiography were performed within 24 hr of each other in 101 patients with symptoms of coronary artery disease. Coronary artery calcifications with a density above 90 H were identified on each slice and, with the same regions of interest, quantitative scoring was performed at thresholds of 90 H (new) 130 H (old). Two mathematical algorithms (one new and one old) were evaluated for both thresholds (yielding four scoring systems). By CT imaging, we defined disease as a score of greater than zero. By angiography, we defined disease as a 50% or greater reduction in the luminal diameter of any major vessel. Interobserver variations in calcification scoring were evaluated. Seventeen of our patients. also underwent a second, consecutive CT scan to determine reproducibility.

RESULTS

With the new threshold and the new algorithm, the sensitivity, specificity, and accuracy of helical CT in predicting disease were 88%, 52%, and 76%, respectively. We found a moderate positive association between the total CT calcification score and the number of stenotic coronary arteries at angiography (Pearson's correlation coefficient, .43; p = .05 [analysis of variance]). The accuracy and the area under the receiver operating characteristic curve were higher with the new threshold and the new algorithm. Interobserver agreement in calcification scoring was high (intraclass correlation coefficient, .99 [n = 85]), as was reproducibility (intraclass correlation coefficient, .94 [n = 17]). Reproducibility was higher when scoring was based on the new threshold and the new algorithm.

CONCLUSION

The quantity of coronary artery calcifications as measured by helical CT correlated positively with obstructive coronary artery disease as measured by angiography. Interobserver agreement and reproducibility were excellent. A new scoring method showed promise.

Comparison of spiral CT scan and arteriography for evaluation of renal and visceral arteries

Renal and visceral artery images obtained concurrently with spiral CT and conventional arteriography were compared for 32 patients. Indications for imaging were occlusive disease (n = 12), aneurysmal disease (n = 9), and renal or visceral artery disease (n = 11). Conventional arteriography enabled visualization of 64 renal arteries and 15 accessory renal arteries. Lateral aortograms obtained in 15 patients enabled visualization of 14 superior mesenteric (SMA) and 14 celiac arteries. Spiral CT enabled visualization of 60 renal arteries, 12 accessory renal arteries, 27 SMAs, and 22 celiac arteries. Calcification or a disparity in timing of contrast material injection and scanning prevented visualization of the celiac artery in 10 patients and the SMA in four patients. With conventional arteriography as the standard for comparison, spiral CT had a sensitivity of 67% and a specificity of 95% for depiction of at least 75% stenosis in the main renal artery. By means of the Pearson correlation coefficient, significant correlation (p < 0.001) was confirmed between spiral CT and arteriography for evaluation of stenosis of the main renal artery, SMA, and celiac artery. This early experience suggests that spiral CT may be useful in evaluation of renal and visceral arteries and their relationship to aortic disease.

Improved accuracy of computerized tomography based clinical staging in low stage nonseminomatous germ cell cancer using size criteria of retroperitoneal lymph nodes

PURPOSE

We evaluated the significance of retroperitoneal lymph nodes detected by computerized tomography (CT) of low stage nonseminomatous germ cell tumor patients.

MATERIALS AND METHODS

A blind retrospective review of 143 CTs of low stage nonseminomatous germ cell tumor revealed pathological stage A disease on 89 (62.2%) and pathological stage B disease on 54 (37.8%). A multivariate logistic regression model was used to evaluate the relationships between diameter of the retroperitoneal nodes detected in these CTs and pathological stage.

RESULTS

Based on this model, as the diameter of the nodes increased within a 0 to 25 mm. range, the likelihood of pathological stage B disease increased in a continuous fashion. Using a 3 mm. threshold to define nonmetastatic nodes the sensitivity and negative predictive value of CT based staging was 90%.

CONCLUSIONS

This measurement scheme improves the accuracy of staging compared to conventional methods.

Hydrocele of the canal of Nuck: ultrasound appearance

Swelling in the inguinal region of a woman may result from a number of conditions, including inguinal hernia, tumor (lipoma, leiomyoma, sarcoma), cyst, abscess, adenopathy, or hydrocele of the canal of Nuck. It may be difficult to make a specific diagnosis based upon the history and physical examination alone. This report describes a symptomatic woman in whom ultrasound was helpful in diagnosing a hydrocele of the canal of Nuck, which is the female counterpart of a spermatic cord hydrocele in the male. The ultrasound findings are described.

Duplex Doppler endosonography in the diagnosis of splenic vein, portal vein, and portosystemic shunt thrombosis

BACKGROUND/AIMS

Endoscopic ultrasonography is a promising procedure for imaging mesenteric vascular structures.

METHODS

Duplex and color Doppler endosonography were used to prospectively evaluate 20 asymptomatic paid volunteers. Subsequently, 11 patients with nondiagnostic transabdominal ultrasound and suspected thrombosis of the splenic and/or portal veins or a portosystemic shunt were evaluated with duplex endosonography. The final diagnosis was based on CT, angiography, and/or surgery or autopsy findings in 9 of 11 patients.

RESULTS

In normal volunteers, mesenteric vessel flow velocities and diameters were similar to previously described values. In 10 of the 11 patients with failed transabdominal ultrasound, duplex endosonography was able to provide the correct diagnosis (accuracy of ultrasound 0% versus EUS 91%, p < .001). Mean portal vein diameter was greater in the patient group than in the normal volunteers (18.5 mm versus 10.7 mm, p < .001) and all of the normal volunteers had a portal vein diameter less than 13 mm. No complications were experienced.

CONCLUSION

Duplex endosonography allows visualization of the intra-abdominal vasculature and can be considered when transabdominal ultrasound is nondiagnostic in patients with suspected thrombosis of their splenic vein, portal vein, or portosystemic shunt. EUS is able to identify indirect findings of portal hypertension including portal vein enlargement and venous collaterals.

Color Doppler flow imaging for deep venous thrombosis screening in patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy for prostatic carcinoma

Patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy are traditionally considered to be at high risk for postoperative venous thromboembolic complications. A prospective deep venous thrombosis screening regimen was initiated at our medical center in 1990 following 2 cases of fatal pulmonary embolism that occurred after hospital discharge. During a 3-year period 245 consecutive patients undergoing radical retropubic prostatectomy for prostate cancer were screened postoperatively for lower extremity deep venous thrombosis using ultrasound duplex scanning with color Doppler flow imaging. The results were correlated only with the development of clinical deep venous thrombosis. No additional diagnostic modalities were used to confirm a normal venous system in asymptomatic patients. Venous thromboembolic complications were encountered in 9 of the 245 patients (3.6%). In 2 patients deep venous thrombosis was associated with nonfatal pulmonary embolism. Only 2 of the 9 cases of deep venous thrombosis were detected by color Doppler flow imaging screening. The striking decrease in the incidence of deep venous thrombosis following radical prostatectomy in the last decade and the low yield of screening at a single point in time may warrant reconsideration of the need for deep venous thrombosis screening among patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy for prostate cancer.

The role of spiral (helical) computerized tomography with three-dimensional reconstruction in pediatric solid tumors

The ability to accurately assess tumor size and orientation to surrounding vital structures is an important consideration during preoperative evaluation. The authors report on nine children with solid tumors (hepatoblastoma [1], neuroblastoma [2], adrenal cortical carcinoma [2], liver adenoma [1], primitive neuroectodermal tumor [PNET] [1], and stage V Wilms' tumor [2]) for whom tumor resectability was questioned because of the tumors' close proximity to major blood vessels (noted through conventional radiographic imaging). The children had scanning with spiral volumetric acquisition computerized tomography, (CT) which obtains images during continuous rotation of the x-ray source while the patient moves at a constant velocity through the gantry. This technique is rapid (18 to 30 seconds), and is similar with respect to radiation exposure; little or no sedation is required, and the contrast dose is lower than that of conventional CT. Three-dimensional reconstruction of spiral CT imaging provided useful information that allowed successful resection in all nine cases. The authors suggest that spiral CT may become an important imaging modality in the preoperative evaluation of pediatric solid tumors and that further evaluation of this new methodology is warranted.

Intravenous cholangiography with helical CT: comparison with endoscopic retrograde cholangiography

PURPOSE

To determine whether helical computed tomography (CT) performed during intravenous cholangiography can provide useful images of the biliary tree and to compare this technique with endoscopic retrograde cholangiography (ERC).

MATERIALS AND METHODS

Eighteen adult patients with clinically suspected biliary disease who were referred for ERC were first examined with helical CT cholangiography performed 75 minutes after intravenous infusion of 100 mL of 10.3% iodipamide meglumine.

RESULTS

Helical CT cholangiography revealed good opacification of the biliary tree in 13 of 14 patients with serum bilirubin levels less than 2 mg/dL (34 mumol/L) and poor opacification in three of four patients with levels greater than 2 mg/dL. In six of seven patients with choledocholithiasis, the diagnosis was made by means of helical CT cholangiography.

CONCLUSION

Helical CT cholangiography may be a clinically useful method for visualization of the biliary tree in some patients with suspected biliary disease with normal bilirubin levels and in patients in whom attempts at ERC fail.

Spiral CT evaluation of the trachea and bronchi

OBJECTIVE

We report two cases in which spiral CT with three-dimensional (3D) reconstruction was used to evaluate abnormalities of the trachea and bronchi.

MATERIALS AND METHODS

Two patients with known airway abnormalities, one with a carinal tumor and the other with a postoperative bronchial stenosis, had spiral CT of the chest performed. Images were reconstructed in the coronal plane as well as using a curved planar reformat and shaded surface display.

RESULTS

Spiral CT with 3D reconstruction provided excellent anatomic definition of the central airway abnormalities. In our two cases the information provided was used in both the clinical assessment and treatment planning of the patients.

CONCLUSION

Spiral CT was useful in the evaluation of two patients with central airway abnormalities. Further investigation into applications of spiral CT for the evaluation of the central airways appears warranted.

Experimental high-frequency ultrasound can detect graft rejection after small bowel transplantation

Early diagnosis of graft rejection after small bowel transplantation (SBT) can allow prompt institution of vigorous immunosuppressive therapy, with resultant reversal of the rejection process. The current method for graft monitoring is random mucosal biopsy from a stomal site or through an endoscope. However, because early rejection often has a patchy distribution, it could be missed by random biopsy. We hypothesized that the pathological process of rejection would alter acoustic impedance of the tissue and thus change the ultrasonic patterns of the graft intestinal wall. If this hypothesis is correct, then high-frequency endoscopic ultrasound (US) could be used to monitor the entire transplanted bowel and guide the biopsy, with improved yields. This hypothesis was tested in a rat orthotopic SBT model. Sixty-two intestinal specimens (9 isografts, 12 allografts treated with cyclosporine A [CsA], 22 untreated allografts, and 19 intestines from normal rats) were collected for in vitro transluminal US imaging (30 MHz) and histopathologic study. The echo pattern of normal rat intestinal wall consisted of five echo layers that correlated spatially with the histological layers: the innermost hyperechoic layer 1, plus hypoechoic layer 2, corresponded to the mucosa; hyperechoic layer 3, the submucosa; anechoic layer 4, the muscularis propria; and hyperechoic layer 5, the serosa. The isografts and CsA-treated allografts were identical histologically and ultrasonically to normal intestine. However, the echo patterns of the untreated allografts had progressive loss of architectural stratification, with worsening rejection. The change began with patchy indistinctness and disruption of hyperechoic layers 1, 3 and 5, and progressed to total obliteration of the layers, with the intestinal wall becoming a nonstratified hypoechoic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound-guided pediatric liver transplant biopsy using a spring-propelled cutting needle (biopsy gun)

Biopsy is the best way to diagnose allograft rejection, the most common complication following liver transplantation. The authors reviewed 99 consecutive ultrasound-guided cutting needle biopsies in 19 infants and children. Conscious sedation was used with 95 biopsies. General anesthesia was used with four biopsies, all in patients undergoing percutaneous biliary procedures at the same time. Ninety-eight biopsies were diagnostic. Only one major complication occurred: biloma. Ultrasound-guided cutting needle biopsy of pediatric liver transplant patients can be performed safely and efficaciously.

Prospective evaluation of endoscopic ultrasonography and endoscopic retrograde cholangiopancreatography in patients with chronic abdominal pain of suspected pancreatic origin

Twenty asymptomatic paid volunteers (13 females, 7 males, mean age 34 years, range 21-52 years), underwent endoscopic ultrasonography (EUS) to assess variation in the appearance of ductular and parenchymal features of the pancreas. Following this investigation, 69 patients with chronic abdominal pain of suspected pancreaticobiliary origin were evaluated with EUS followed by endoscopic retrograde cholangiopancreatography (ERCP) and in 16 patients secretin stimulated intraductal pure pancreatic juice (PPJ) collection. Thirty patients were found to have chronic pancreatitis based on clinical, ERCP and/or PPJ data, and EUS was abnormal in 24 of these individuals. All of the 19 patients with abnormal pancreatograms also had an abnormal EUS. Twenty-two of the 30 patients with chronic pancreatitis had early disease (no or minimal changes on ERCP). In this subgroup of patients, the sensitivity of EUS was 86% versus 50% for ERCP (p = 0.01). For all patients, the sensitivity, specificity and accuracy of EUS in diagnosing chronic pancreatitis was 80%, 86% and 84% respectively. Using logistic regression analysis eight EUS features were found to be indicative of chronic pancreatitis including echogenic foci within the gland, focal regions of reduced echogenicity within the gland, increased thickness/echogenicity of the main pancreatic duct (MPD) wall, accentuation of the gland's lobular pattern, cysts, an irregular contour or dilation of the MPD and side branch dilation (p < or = 0.05). Generation of a receiver operating characteristic curve to assess the sensitivity and specificity of EUS in diagnosing chronic pancreatitis based on the number of abnormal findings demonstrated that sensitivity and specificity were optimal when three or more abnormal parenchymal and/or ductular features were found. These results suggest that EUS can play an adjunctive role to ERCP and PPJ in the diagnosis of early chronic pancreatitis.

Percutaneous transhepatic drainage of the nondilated biliary system

PURPOSE

The authors sought to develop a safe, efficacious technique for percutaneous transhepatic drainage of nondilated biliary systems.

PATIENTS AND METHODS

Twenty-three drainage procedures were performed on 14 consecutive patients with nondilated ducts. Fourteen procedures were carried out for primary placement of a transhepatic biliary drain, eight for placement of a second drain, and one for placement of a third drain. Drainage catheter access into the biliary tree was gained via direct puncture of a peripheral duct (fourth order or smaller branch) in four procedures. In the remaining 19 procedures, peripheral duct punctures were facilitated by retrograde passage of a 5-F catheter from a previous, remote percutaneous access site into the fourth-order duct to be punctured. Nine of these 19 duct punctures were facilitated by the use of a nitinol Goose Neck snare passed through the intraductal catheter.

RESULTS

Of the access methods used, the nitinol snare technique was the fastest. Successful peripheral access was achieved in all patients without bleeding complications. One patient developed symptoms of bacteremia, which resolved within 12 hours with antibiotic therapy and external biliary drainage.

CONCLUSION

Percutaneous peripheral access can be achieved safely in the nondilated biliary tree and can obviate surgery for some patients and facilitate future interventions.

Sonographic and computed tomography characteristics of liver ablation lesions induced by high-intensity focussed ultrasound

RATIONALE AND OBJECTIVES

The authors have previously demonstrated the ability of high-intensity focused ultrasound (HIFU) to extracorporeally induce selective tissue destruction in the liver without causing damage to the intervening abdominal wall. The potential usefulness of HIFU as a noninvasive therapy for liver cancer has been suggested. This study observes sonographic and computed tomography (CT) characteristics of HIFU-ablated liver tissue in an attempt to assess the possibility of using these imaging methods to monitor the therapeutic results.

METHODS

A sonoablated lesion was induced in the liver in each of 20 rabbits with a HIFU therapeutic system. Sequential imaging of the hepatic sonolesions with sonography and CT was performed up to 8 days after treatment, and the imaging patterns were correlated with the histopathology.

RESULTS

Hepatic sonoablated tissue could be clearly visualized by sonography as a hypoechoic lesion. On contrast-enhanced CT, the sonolesions were depicted as nonenhanced low-density regions. There was good correlation among the sizes of sonography- and CT-depicted lesions and pathologic specimens.

CONCLUSION

In this model, sonography and contrast-enhanced CT were useful imaging modalities for monitoring sonolesion evolution after HIFU treatment.

Changes of hepatoma echo patterns with tumor growth. A study of the microanatomic basis in a rat model

OBJECTIVES

The echo patterns of human hepatoma vary considerably as the tumors grow. This sonographic study investigates the microanatomic basis of the echo-pattern changes in an animal model.

METHODS

ACI rats (n = 35) with intrahepatically implanted Morris hepatoma 3924A were imaged with 10-MHz ultrasound from days 7 to 28 after tumor implantation. The sonograms were precisely correlated with the histologic sections and microangiograms obtained from the same section plane.

RESULTS

Small hepatomas (size = 6.6 +/- 1.6 mm) without necrosis demonstrated a low-echo pattern. Medium-sized tumors (size = 11.7 +/- 3.3 mm) had a low-echo periphery and a high-echo center. The low-echo periphery corresponded to viable tumor and the high-echo core corresponded to central coagulation necrosis. Large tumors (size = 20.9 +/- 7.5 mm) with extensive necrosis revealed an irregular mixed-echo pattern.

CONCLUSIONS

The trend of increasing echogenicity of the hepatomas with tumor growth is due to the progression of coagulation necrosis.

Prospective study of magnetic resonance imaging and SPECT bone scans in renal allograft recipients: evidence for a self-limited subclinical abnormality of the hip

We recently reported that typical abnormalities of avascular necrosis (AVN) in magnetic resonance images (MRI) of the hips of asymptomatic renal transplant recipients whose plain radiographs are normal may improve spontaneously and even disappear completely. We present the results of serial bone scans, most of which were performed with single-photon emission computed tomography obtained over periods as long as 24 mo after transplantation in 72 of these patients. Three paired imaging studies (i.e., MR and bone scan performed within 30 days of each other) were available for each of these patients. In three patients, both the MR images and the bone scans showed changes consistent with bilateral AVN within 4 mo after transplantation. All three patients developed hip pain which was bilateral in two and unilateral in one. Two patients (three hips) required surgical intervention at which time AVN was found on pathologic examination of all three hips. None of the remaining 69 patients developed hip pain during the study. However, in nine patients whose MR studies were consistently normal, at least one bone scan was abnormal (13 hips). The presence of AVN was pathologically confirmed in each of the hips subjected to surgery. Where the imaging findings were identical to those in the asymptomatic patients as well as those in whom the imaging abnormality regressed, we suggest that the subclinical imaging abnormalities represent mild AVN, which is reversible in some cases. Since the process was identified in 10 hips by MRI and in 13 hips by bone scan, both studies are needed to detect subclinical AVN. This may be important if treatment of subclinical disease is clearly shown to prevent progression to symptomatic AVN.

Electrocautery of the tract after needle biopsy of the liver to reduce blood loss. Experience in the canine model

RATIONALE AND OBJECTIVES

Bleeding is the most common complication of needle biopsy of the liver. This study was designed to assess the feasibility of using unipolar electrocautery to decrease bleeding.

METHODS

Under general anesthesia, the livers of eight dogs were surgically exposed. A mean of 15 biopsies was obtained with 18-gauge needles from each liver by alternating biopsies without and with electrocautery. Cautery was performed by applying radiofrequency energy at 25 watts (6 animals) or 125 watts (2 animals) to the needle as the needle was withdrawn from the liver. Blood loss was measured by applying preweighed sponges to the biopsy site, then reweighing them after use. Biopsy specimens were examined by light microscopy.

RESULTS

The mean (+/- SD) blood loss was 0.44 g (+/- 1.36 g) with electrocautery and 1.47 g (+/- 2.23 g) without electrocautery (P < .01). No thermal injury was noted in the biopsy specimens when cautery was applied at 25 watts.

CONCLUSIONS

The application of radiofrequency current to the biopsy needle after liver biopsy is a feasible and effective method to reduce blood loss in our canine model.

Liver cancer ablation with extracorporeal high-intensity focused ultrasound

Recent animal studies have demonstrated the capacity of high-intensity focused ultrasound (HIFU) to extracorporeally ablate selective tissue targets in the liver without requiring surgical exposure of the liver or insertion of instruments into the liver. The potential value of HIFU as a noninvasive local treatment for human hepatic cancers has attracted considerable interest. This report reviews the current status of HIFU research and sets forth questions for future study.