Biomedical subjects
Publications and source records attributed to Mark E Lockhart.
Learning how to perform endovaginal pelvic ultrasound is often challenging for novices in a busy clinical practice. In this article, we describe a program in which we hired female patient models to help residents acquire basic endovaginal scanning skills.
OBJECTIVE: To optimize forearm radiocephalic fistula success, many programs recommend a minimal cephalic vein diameter of 0.25 cm or greater on preoperative sonographic mapping. It is not established, however, whether a vein diameter before or after application of a tourniquet should be used in determining suitability for creation of a forearm fistula. METHODS: Before forearm radiocephalic fistula placement, preoperative sonographic mapping measured the cephalic vein diameter before and after application of a tourniquet. The patients fell into 2 groups: those with a pretourniquet vein diameter of 0.25 cm or greater (group 1) and those with a pretourniquet vein diameter of less than 0.25 cm that increased to 0.25 cm or greater after application of the tourniquet (group 2). The adequacy of each fistula for dialysis was determined clinically. RESULTS: Among 73 radiocephalic fistulas with known clinical outcomes, 28 were in group 1, and 45 were in group 2, on the basis of sonography. Fistula success rates were similar in group 1 patients (11 [39%] of 28) and group 2 patients (15 [33%] of 45) (P=.624, Fisher exact test). Inclusion of group 2 patients increased the number of patients recommended for placement of forearm fistulas and increased the total number of usable forearm fistulas from 11 to 26. The overall success rate of forearm fistulas was lower in women (19% versus 50%; P=.015, Fisher exact test). CONCLUSIONS: The use of a venous tourniquet increases the number of patients eligible for forearm fistulas without decreasing the adequacy rate of these fistulas. Therefore, a tourniquet should routinely be used in patients with small cephalic veins on pretourniquet evaluation.
OBJECTIVE: The purpose of our study was to evaluate the usefulness of venous flow augmentation with duplex sonography in the evaluation of deep venous thrombus of the lower extremities. CONCLUSION: The augmentation component of the lower extremity sonogram rarely provides additional information in the diagnosis of deep venous thrombus. In our large series, no deep venous thromboses were discovered with augmentation. Factors such as the lack of usefulness and patient discomfort may justify removal of augmentation from the routine study. However, augmentation should still be applied as a diagnostic tool in difficult or uncertain cases.
BACKGROUND: Arterial calcification is a common problem in patients with chronic kidney disease, and has been associated with adverse clinical outcomes. The goal of the present study was to evaluate whether pelvic artery calcifications are associated with technical failure of arteriovenous thigh grafts in haemodialysis patients. METHODS: From 1 January 1999 to 30 June 2002, thigh grafts were placed in 54 haemodialysis patients who had exhausted all options for permanent vascular access in the upper extremities. Perioperative computed tomography (CT) of the abdomen and pelvis was obtained in 32 of the patients for diagnostic purposes unrelated to vascular access planning. Two radiologists, who were blinded to the graft outcomes, scored the vascular calcifications on CT of the distal aorta, common iliac, external iliac and common femoral arteries on a semi-quantitative 5-point scale. The association between technical graft failure (inability to complete the anastomosis) and the vascular calcification score was analysed. RESULTS: There was a high inter-observer agreement in scoring vascular calcification (kappa = 0.801). Among 26 patients with absent or mild pelvic arterial calcifications (grade 1-2) on CT, none (0%) experienced technical graft failure. In contrast, three of six patients (50%) with moderate to severe calcification (grade 3-5) had technical graft failures (P = 0.004 by Fisher's exact test). The cumulative 1 year graft patency was lower in the group with grade 3-5 calcification (33 vs 81%, P = 0.09). The two groups were similar in age, gender, race, diabetes, duration of dialysis, serum calcium, serum phosphorus and serum parathyroid hormone. CONCLUSION: There is a strong association between pelvic artery calcifications and technical failure of thigh grafts. The presence of moderate to severe vascular calcification is predictive of poor cumulative 1 year graft patency.
Doppler ultrasound is useful in the emergent evaluation of the liver and kidney transplant patient. Arterial stenosis, pseudoaneurysm, and venous thrombosis are treatable causes of allograft failure that can be detected easily with color and spectral Doppler. Doppler has a limited but important role in the emergent evaluation of the native liver and kidneys, usually involving prior biopsy or instrumentation.
OBJECTIVES: To review the outcomes for live donor renal transplantation using kidneys with fibromuscular dysplasia. METHODS: We performed a retrospective review and searched a departmental database to identify all renal donors with fibromuscular dysplasia from 1995 through 2001. These donors were then paired with the recipient using the institution's renal transplant database. A single radiologist reviewed the original arteriographic studies. Mild disease was defined as mild irregularity of the artery without significant stenosis. Moderate disease was defined as arterial irregularity with less than 50% stenosis. Severe disease was defined as irregularity with greater than 50% stenosis or with aneurysms. RESULTS: Thirty-six donor/recipient pairs were identified. Twenty-six donors had unilateral and 10 bilateral disease. Twenty-eight had mild and eight moderate disease. Four grafts were lost during the follow-up period (three acute rejection and one chronic rejection) for an overall graft survival rate of 89%. The median graft survival/follow-up was 37.1 months (range 0.5 to 82). The median serum creatinine was 1.6 mg/dL. The median systolic and diastolic blood pressure was 155 and 82 mm Hg, respectively. Six recipients required no antihypertensive agents. All but 9 of the remaining patients required two or fewer antihypertensive agents. CONCLUSIONS: Selected patients with medial fibroplasia can be used as renal donors, and satisfactory functional outcomes can be achieved. Renal donors with mild anatomic abnormalities such as medial fibroplasia could be used to increase the potential donor pool and decrease the waiting time for renal transplantation.
PURPOSE: To evaluate the frequency of detection of trauma-induced adrenal gland hematoma in current practice by using computed tomography (CT) and to correlate presence of adrenal hematoma with quantitative clinical indicators of injury severity. MATERIALS AND METHODS: The radiology information system and the trauma registry were searched for cases of adrenal hematoma detected at trauma CT during a 54-month period. CT images depicting adrenal masses with the published characteristics of adrenal hematoma were reviewed by readers who were unblinded to the initial interpretations. Injury severity score (ISS), associated injury, and patient outcome data were gleaned from the trauma registry. The control group comprised patients entered in the trauma registry during the study period who did not have a diagnosis of adrenal hematoma. RESULTS: Fifty-four adrenal hematomas were detected in 51 patients: 42 with right-gland, 12 with left-gland, and three with bilateral lesions. The hematomas were round or ovoid and had a mean maximum diameter of 2.8 cm +/- 0.7 (SD) and a mean attenuation of 52 HU +/- 12. Periadrenal stranding was seen with 48 (89%) hematomas. At follow-up CT, 32 of 35 hematomas had resolved or decreased in size and attenuation. One patient with adrenal hematoma had no other intraabdominal injuries. Compared with the 6,757 control patients, the 51 patients with adrenal hematoma had a higher mortality rate (10% vs 4%; P <.001, chi(2) test) and a higher mean ISS (25.2 vs 9.7; P <.01, t test). Adrenal hematoma was found in 24 (0.4%) of 5,665 trauma patients with an ISS of 0-19, as compared with six (5.0%) of 122 patients with an ISS of 40 or higher. CONCLUSION: Adrenal hematoma was detected in 51 (1.9%) of 2,692 trauma patients who underwent CT, or 0.8% of all patients (n = 6,808) entered in the trauma registry. Compared with the other trauma patients, the patients with adrenal hematomas had severe injuries associated with higher mortality.
OBJECTIVE: Primary failure of forearm radiocephalic dialysis fistulas is common even when preoperative vascular mapping is used. Previous studies have suggested that low peak systolic velocity of the radial artery predicts subsequent fistula failure. The study goal was to evaluate whether preoperative spectral Doppler assessment of radial artery inflow can improve forearm fistula outcome prediction. METHODS: Forearm fistulas were placed in 112 patients after preoperative sonographic mapping. Preoperative spectral Doppler sonography measured radial artery peak systolic velocity during tight fist clenching for 3 minutes and after fist relaxation. Vessel diameters and peak systolic velocity were assessed for predictive value based on subsequent fistula adequacy. Fistula flow rates were determined 6 to 12 weeks postoperatively in a subset of patients. RESULTS: Failed and successful fistulas were similar in their preoperative arterial and vein diameters, resistive index, and peak systolic velocity during fist clenching and after fist relaxation. Specifically, there was no difference in fistula success with radial artery peak systolic velocity lower than 50 cm/s versus peak systolic velocity of 50 cm/s or higher. The change in peak systolic velocity after fist relaxation was highly predictive of subsequent fistula outcome among female patients in ad hoc analysis. Fistula adequacy for dialysis in women was 11% when the change in peak systolic velocity was lower than 0 cm/s and 50% when the change was 0 cm/sec or higher (P = .02). The postoperative fistula flow rates were lower when the preoperative change in peak systolic velocity was lower than 0 cm/s than when it was 0 cm/s or higher (316 +/- 46 versus 781 +/- 150 mL/min; P = .003). CONCLUSIONS: There was no difference in the preoperative peak systolic velocity or the resistive index of successful and failed fistulas. Measurement of the radial artery peak systolic velocity change after release of fist clenching was not useful in predicting outcomes in male patients but identified a subset of female patients with a very low likelihood of success. This criterion may merit further investigation in future trials.
Computed tomography (CT) diagnosis of pneumatosis involving the gastrointestinal tract can represent a broad range of clinical entities from a benign process to ischemic bowel. The purpose of this study is to define the significance and outcome of pneumatosis intestinalis (PI). All CT scans from 5/93 to 12/01 with the finding of PI were reviewed. Eighty-six CT scans had the finding of PI, with the colon being the most frequent location (51%), followed by small bowel (36%) and gastric (9%). Forty per cent of patients underwent surgery, with an overall mortality rate of 42 per cent and a surgical mortality rate of 47 per cent. Univariate analysis demonstrated significant correlation between serum lactic acid (LA) > 2.0 mmol/L [odds ratio (OR) = 23.4; 95% confidence interval (C.I.), 7.21-75.92] and serum creatinine > 1.5 mg/dL (OR = 3.05; 95% C.I., 1.25-7.42) with mortality. Age was suggestive but not a significant risk factor for mortality (P = 0.09). Multivariate analysis found serum LA > 2.0 (OR = 30.37; 95% C.I., 7.31-126.2) to be the only significant predictor of mortality. CT diagnosis of PI is associated with significant in-hospital mortality, especially in the elderly. Serum LA level > 2.0 mmol/L at time of diagnosis is associated with a greater than 80 per cent mortality. Surgical consultation is necessary to determine which patients need urgent surgical intervention.
CT is a robust, rapid means of evaluation for a wide spectrum of urologic disorders. The evaluation of renal trauma, urologic malignancy, urolithiasis, and vascular anatomy is well suited to CT techniques. Subtle adjustments in the technical parameters and timing of the study, however, can optimize the evaluation based on the clinical setting. As CT is more widely used, often repeatedly on an individual patient, radiation exposure must be minimized while still obtaining diagnostic image quality.
The application of UCAs to the kidney is still in its infancy; however, there are several areas of great promise. UCAs may replace CT in complex renal cyst evaluation and follow-up, eliminating the need for costly CT scans with their attendant potential contrast nephrotoxicity. This approach may decrease patient and physician uncertainty and improve diagnostic confidence. The use of UCAs is likely to be clinically useful in the evaluation of the indeterminate small renal mass on CT or MR imaging. Another probable useful application will be in renal artery stenosis. Routine application of UCAs may increase the percentage of diagnostic examinations, increase diagnostic confidence, and decrease examination times. It also will likely become the first line of evaluation in pyelonephritis, and be useful in immediate assessment of residual tumor after radiofrequency ablation. Of course, substantial additional work needs to be performed in large groups of patients to prove this currently optimistic outlook.
OBJECTIVE: The purpose of our study was to determine the effectiveness, clinical impact, and feasibility of double reading barium enemas. MATERIALS AND METHODS: Independent double readings of 1,003 consecutive barium enemas (822 double- and 181 single-contrast examinations) were prospectively performed. From this pool of 1,003 examinations, 994 were included in our study. Examinations showing at least one polyp or carcinoma 5 mm or larger were considered to have positive results. For combined readings, results were considered positive if either of the two interpreters reported finding a polyp or carcinoma. A McNemar test was used to compare the first reader's results with the combined results of the first and second readers. Results were retrospectively correlated with endoscopic or surgical results in 360 patients, and agreement between first and combined readings and endoscopic results was determined. RESULTS: Adding a second reader increased the number of positive results on examinations from 249 to 315 (p < 0.0001) and resulted in potential alteration of clinical treatment in 98 patients (9.9%). Sensitivity of the first and combined readings for detection of all lesions was identical, 76.3% (95% CI, 65.4-87.1%). Specificity decreased from 91.0% (95% CI, 87.9-94.3%) for the first reading to 86.4% (95% CI, 82.2-90.0%) for the combined reading. The overall measurement of agreement decreased from a kappa value of 61.8 (95% CI, 51.2-72.4%) for the first reading to 52.9 (95% CI, 42.2-63.6%) for the combined reading. The second reading required an average of 3.3 min. Sensitivity for the detection of adenocarcinomas was 100%. CONCLUSION: Although feasible, double reading of barium enemas does not improve sensitivity for detection of polyps and produces a higher false-positive rate.
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PURPOSE: Cystic ectasia of the rete testis is a rare condition that may be incidentally noted on scrotal ultrasonography. This benign condition has a typical appearance of a collection of small anechoic structures in the confluence of the mediastinum testis. The main significance of this condition is that it must be differentiated from testicular neoplasm. We reviewed the experience with this condition at our institution. MATERIALS AND METHODS: A retrospective review was performed to identify all sonograms showing ectatic rete testis performed from 1998 through February 2002. A departmental database was used to identify all scrotal sonograms from this period showing ectasia of the rete testis and clinical correlation was done. These examinations were then reviewed by a single radiologist. RESULTS: We identified 13 cases in the last 4 years. Ultrasound was most commonly performed for a testicular or scrotal mass, or pain. Median patient age was 65 years. All except 1 patient had an underlying condition, including vasectomy, epididymal cyst/spermatocele or inguinal hernia repair, that could cause epididymal or efferent duct obstruction. No patient had a solid testicular mass. CONCLUSIONS: Based on clinical and sonographic criteria the diagnosis of cystic ectasia of the rete testis can be made without histological confirmation. Identifying this entity and its associated conditions avoids the need for biopsy or orchiectomy.
Adrenal pathology may be discussed based on hormonal functionality of the adrenals, appearances on imaging modality, or pathological determination. There are three main categories of adrenal function. Hyperfunctional states include Conn's or Cushing's syndrome. Lesions with normal function may be detected incidentally. Hypofunctional states may occur from idiopathic Addison's disease or some bilateral adrenal pathology. The most common modalities for characterization of adrenal pathology are non-enhanced CT, often followed by contrast CT or chemical shift MRI. The common appearance on non-enhanced CT is a well-defined homogeneous lesion with low-density due to the microscopic fat present and adrenal adenomas. When density criteria are not met, many of these may be characterized as adenomas by washed out of contrast or signal decrease using in phase and out-of-phase MRI sequences. Other non-invasive modalities may incidentally discover adrenal lesions, but are not typically used in the work-up. NP-59 is an uncommonly used nuclear medicine technique which is very specific for adenoma when correlated with pathology on other imaging studies. In the rare cases where non-invasive imaging is non-specific, fine needle aspiration or core biopsies may be necessary. However, biopsies have associated risks including infection and hemorrhage. The imaging appearance of an adrenal lesion is often specific such that further imaging is not necessary. These lesions include adrenal adenoma, pheochromocytoma, myelolipoma, adrenal cyst, and some large adrenocortical carcinomas. However, the findings in lesions such as metastasis, smaller primary adrenal carcinomas, lymphoma, granulomatous disease, and many adenomas are not as specific. In the proper clinical situation, follow-up imaging may be necessary, or biopsy may be warranted.
PURPOSE: To compare various objective ultrasonographic (US) criteria for native arteriovenous fistula (AVF) maturation with subsequent fistula outcomes and clinical evaluation by experienced dialysis nurses. MATERIALS AND METHODS: US fistula evaluation results were analyzed retrospectively in 69 patients within 4 months after AVF placement; adequacy for dialysis was known in 54. Measurements included minimum venous diameter and blood flow rate. Experienced dialysis nurses examined 30 fistulas clinically. Predictors of fistula adequacy were analyzed with univariate and multivariate logistic regression. Mean fistula diameters and blood flow rates were compared by using analysis of variance or unpaired Student t tests. RESULTS: Fistula adequacy for dialysis doubled if the minimum venous diameter was 0.4 cm or greater (89% [24 of 27]) versus less than 0.4 cm (44% [12 of 27]; P <.001). Fistula adequacy for dialysis was nearly doubled if flow volume was 500 mL/min or greater (84% [26 of 31]) versus less than 500 mL/min (43% [nine of 21]; P =.002). Combining venous diameter and flow volume increased fistula adequacy predictive value: minimum venous diameter of 0.4 cm or greater and flow volume of 500 mL/min or greater (95% [19 of 20]) versus neither criterion met (33% [five of 15]; P =.002). Women were less likely to have an adequate fistula diameter of 0.4 cm or greater: 40% (12 of 30) of women versus 69% (27 of 39; P =.015) of men. No significant differences in blood flow or minimum venous diameter were found during 2-4 postoperative months. Experienced dialysis nurses' accuracy in predicting eventual fistula maturity was 80% (24 of 30). CONCLUSION: US measurements of AVF at 2-4 months in patients undergoing hemodialysis are highly predictive of fistula maturation and adequacy for dialysis.
Polycystic liver disease (PLD) is usually associated with polycystic kidney disease but may also occur as an isolated finding in a rarer genetically distinct disease. In either case, the cyst burden will progress over time and, in rare cases, may affect liver function or become symptomatic due to massive hepatomegaly. The character, distribution, location, and size of hepatic cysts are important. Computed tomography, magnetic resonance imaging, or ultrasonography may provide the surgeon with valuable preoperative information, such as the location of infected or hemorrhagic cysts that may be responsible for symptoms. Less invasive cyst aspiration or fenestration may provide temporary relief from dominant or symptomatic cysts, but these cysts will recur in up to 75% of patients. Cyst fenestration with partial hepatic resection and liver transplantation are two therapies that provide more permanent resolution of symptoms in patients with extensive hepatic involvement. However, the higher risk of complications associated with more aggressive surgical therapy must be considered when determining the appropriate therapy for a given patient. Knowledge of the cyst patterns and available treatment options in patients with PLD will help the radiologist provide the referring clinician with important information for therapeutic decision making.