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Peter F Hahn

Publications and source records attributed to Peter F Hahn.

At least 37 records · Page 2Linked to original sources
PubMed2005

Detection of liver metastases from adenocarcinoma of the colon and pancreas: comparison of mangafodipir trisodium-enhanced liver MRI and whole-body FDG PET.

OBJECTIVE: The objective of our study was to assess the relative performance of mangafodipir trisodium-enhanced liver MRI and whole-body FDG PET for the detection of liver metastases from adenocarcinoma of the colon and pancreas. MATERIALS AND METHODS: Imaging data of 34 patients (23 men, 11 women; age range, 44-78 years) with adenocarcinoma of the colon (n = 27) or adenocarcinoma of the pancreas (n = 7) who had undergone mangafodipir trisodium-enhanced liver MRI and whole-body FDG PET were retrospectively reviewed for the presence and number of liver metastases. Histopathology (n = 25) or follow-up imaging (n = 9) served as the standard of reference. Breath-hold T1-weighted gradient-recalled echo, respiratory-triggered T2-weighted fast spin-echo, and mangafodipir trisodium-enhanced axial fat-saturated high-spatial-resolution (256 x 512) T1-weighted gradient-recalled echo images were obtained on a 1.5-T scanner. FDG PET was performed after the injection of 15-20 mCi (555-740 MBq) of FDG. The sensitivity, positive predictive value, and accuracy were calculated for each technique. The performances of the two techniques were compared using the Fisher's exact test. RESULTS: Thirty patients had hepatic metastases and four had no hepatic metastases according to the standard of reference. The total number of metastases was 79, including 33 that measured less than 1 cm. Based on a per-patient analysis, MRI and FDG PET showed sensitivities of 96.6% and 93.3%, positive predictive values of 100% and 90.3%, and accuracies of 97.1% and 85.3%, respectively. According to a per-lesion analysis, MRI and FDG PET showed sensitivities of 81.4% and 67.0%, positive predictive values of 89.8% and 81.3%, and accuracies of 75.5% and 64.1%, respectively. MRI detected more hepatic metastases than FDG PET (p = 0.016). Of the 33 subcentimeter lesions confirmed on the standard of reference, all were identified on MRI, whereas only 12 were detected on FDG PET (p = 0.0001). CONCLUSION: In patients with colon and pancreatic adenocarcinoma, high-spatial-resolution mangafodipir trisodium-enhanced liver MRI and whole-body FDG PET were comparable in the detection of patients with liver metastases. FDG PET provided additional information about extrahepatic disease and was useful in initial staging. However, significantly more and smaller liver metastases were detected on MRI than on FDG PET.

Adenocarcinoma↗
PubMed2004

Haemolysis, elevated liver enzymes and low platelets syndrome: ultrasound and magnetic resonance imaging findings in the liver.

We describe the imaging findings of the HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome in a gravid 36-year-old-woman who presented at 19.5 weeks gestation with severe right upper quadrant pain. Ultrasound findings suggested a focal hyperechoic liver lesion suggesting pregnancy-related hepatopathy prior to development of biochemical signs of HELLP syndrome. Within 3 days, the patient developed characteristic clinical and laboratory evidence of the HELLP syndrome. MR imaging at this time demonstrated localized hepatic ischaemia, further strengthening the diagnosis of HELLP syndrome.

Adult↗
PubMed2004

Pheochromocytoma: an imaging chameleon.

Pheochromocytomas are rare catecholamine-secreting tumors with many clinical and imaging manifestations. They may produce overwhelming cardiovascular crises if the diagnosis is not made or if appropriate treatment is delayed. It is thus important to recognize both their characteristic and atypical imaging appearances. Pheochromocytomas are encountered, sometimes unexpectedly, across a range of imaging modalities. They are characteristically solid, hypervascular masses with high signal intensity on T2-weighted magnetic resonance (MR) images. A wide spectrum of imaging appearances is seen, however, and pheochromocytomas may mimic other adrenal lesions, both benign and malignant. They may be dark on T2-weighted MR images, in contrast to their more classic bright T2-weighted appearance. Other atypical features include fatty, hemorrhagic, cystic, and calcific changes. Pheochromocytomas may contain sufficient fat to be mistaken for an adenoma at computed tomography (CT) or MR imaging. They may also demonstrate rapid contrast material washout and be mistaken for an adenoma owing to their deenhancement profile; however, their washout pattern can be inconsistent. The appearance of pheochromocytomas at radionuclide imaging is also unpredictable. These characteristics at CT, MR imaging, and scintigraphy pose diagnostic challenges, since they allow pheochromocytomas to mimic many other adrenal masses. Pheochromocytoma is an important, often clinically occult neoplasm with devastating consequences if overlooked. Radiologists must be aware of the various forms that pheochromocytomas can assume at imaging.

Adrenal Gland Neoplasms↗
PubMed2004

Recurrent abdominal and pelvic abscesses: incidence, results of repeated percutaneous drainage, and underlying causes in 956 drainages.

OBJECTIVE: We undertook this study to determine the incidence and results of repeated (secondary) percutaneous abscess drainage performed on recurrent abscesses after successful initial (primary) percutaneous abscess drainage. MATERIALS AND METHODS: Imaging studies from patients who underwent multiple drainages were reviewed to define a cohort of patients who underwent secondary percutaneous abscess drainage after successful initial percutaneous abscess drainage of the same abscess. Medical records of these patients were then reviewed to assess the results of secondary percutaneous abscess drainage. RESULTS: Forty-five abscesses in 43 patients required secondary percutaneous abscess drainage. Twenty-four of the 43 patients avoided surgery. Secondary percutaneous abscess drainage was successful in evacuating the abscess cavity in 39 (91%) of 43 patients. Duration of drainage and time until recurrence were not significant predictors for avoiding surgery. Mean duration of secondary percutaneous abscess drainage was significantly longer than mean duration of primary percutaneous abscess drainage, but duration of secondary percutaneous abscess drainage (25 vs 14 days, respectively; p = 0.007) did not differ significantly between patients who ultimately required surgery and those who did not (17 vs 11 days, respectively; p = 0.10). Time to recurrence ranged from 2 days to 1 year (mean, 51 days). CONCLUSION: After successful primary percutaneous abscess drainage, secondary percutaneous abscess drainage of recurrent abscesses succeeded in evacuating the abscess cavity in most patients, and surgery was avoided by slightly more than half. Patients with postoperative abscesses were significantly more likely to avoid surgery (p = 0.008), whereas patients with pancreatic abscesses were significantly more likely to require it (p = 0.03).

Abdominal Abscess↗
PubMed2004

Enteric feeding with gastric decompression: management with separate gastric accesses.

OBJECTIVE: Our purpose is to describe our experience with combined enteral feeding and gastric decompression or drainage in debilitated patients with persistent gastroesophageal reflux using two separate catheters. CONCLUSION: The placement of two percutaneous catheters through separate skin sites is a feasible and successful approach to providing enteral feeding and gastric decompression or drainage in debilitated patients with persistent gastroesophageal reflux and aspiration pneumonia.

Adolescent↗
PubMed2004

Portable abdominal CT: analysis of quality and clinical impact in more than 100 consecutive cases.

OBJECTIVE: Our aim was to determine portable abdominal CT image quality and clinical content in a consecutive series of scans obtained in ICUs at a single center. MATERIALS AND METHODS: All helical portable abdominal CT scans obtained between June 1999 and December 2000 were reviewed by two observers. Image quality was assessed for feature detection and overall quality compared with the patients' contemporaneous stationary CT scans. Hospital records were used to determine patient demographics, scanning indications, and clinical impact and to verify portable CT findings when possible. RESULTS: One hundred twenty-two helical portable CT scans (47 contrast-enhanced) and 41 contemporaneous stationary CT scans in 107 patients were included. IV contrast material improved portable CT scan quality, but quality scores for portable CT scans were consistently lower than those for stationary CT scans, both with and without contrast material. Thirty-three conditions suspected before scanning were supported by findings on portable CT scans, which detected evidence of infection in 18 and hemorrhage in 16 cases and motivated seven laparotomies and six percutaneous drainage procedures. Thirty-three portable CT scans (27%) contributed to a change in patient treatment. Results of surgery or autopsy confirmed portable CT findings in 12 of 17 cases. CONCLUSION: Although image quality is inferior to conventional stationary CT, portable abdominal CT provides important diagnostic information without requiring patient transport outside the ICU. Radiologists should avoid overconfident interpretation of portable CT scans.

Adolescent↗
PubMed2004

CT appearance of acute appendagitis.

OBJECTIVE: Our aim was to describe the spectrum of CT findings in patients with acute epiploic appendagitis and also to evaluate the changes seen with this condition. MATERIALS AND METHODS: Fifty patients diagnosed with acute epiploic appendagitis seen on contrast-enhanced CT were included in this study. The CT scans of the epiploic appendagitis were evaluated for the presence of colon wall thickening, a focal fatty center, inflammatory changes, location in relationship to the colon, size, and presence or absence of central high density within the fat. In 10 patients, the initial findings were compared with findings of follow-up CT performed between 3 days-21 months after the first CT. RESULTS: The most common part of colon involved by acute epiploic appendagitis was the sigmoid colon (31/50), and the most common position was anterior to the colonic lumen (41/50). All 50 patients with acute epiploic appendagitis had a central fatty core surrounded by inflammation. Colon wall thickening was present in only two, and a central high-density focus was noted only in 27 of 50 patients. In 86% (43/50) of patients, the fatty central core was between 1.5 and 3.5 cm in length. The changes seen on follow-up CT varied, including increased density with a decrease in the size of the fatty central core, no change, complete resolution of findings, and minimal residual density. CONCLUSION: On CT, acute epiploic appendagitis has a predictable appearance in terms of location, size, and density. The most common finding on CT is a fat-density oval lesion with surrounding inflammation on the anterior aspect of the sigmoid colon. The changes on CT are not predictable in the 2-week to 6-month window.

Abdomen, Acute↗
PubMed2003

Transgluteal approach for percutaneous drainage of deep pelvic abscesses: 154 cases.

PURPOSE: To assess the effectiveness of a computed tomographic (CT) image-guided transgluteal approach for percutaneous drainage of deep pelvic abscesses as an alternative to surgical drainage. MATERIALS AND METHODS: The medical records of 140 patients who underwent percutaneous CT-guided transgluteal drainage of 154 deep pelvic abscesses were reviewed to determine the origins, location, and size of the abscesses; volume of initial aspirate; organisms identified in fluid culture; duration of catheter drainage; incidence of catheter-related pain and procedure-related complications; and short- and long-term outcomes. The resultant data were analyzed with a Fisher exact test for difference in the incidence of postprocedural catheter-site pain between transpiriformis and infrapiriformis approaches. RESULTS: The origins of the pelvic abscesses included postoperative fluid collection (n = 115), perforating appendicitis (n = 6), diverticulitis (n = 16), tubo-ovarian inflammation (n = 5), Crohn disease (n = 10), and internal bowel fistula due to irradiation (n = 2). The abscesses were 4-12 cm in diameter. The volume of the aspirate was 5-310 mL. Laboratory cultures of the aspirate grew mixed flora, but the organism most frequently isolated was Escherichia coli. Catheters were removed after a mean of 8 days. In 134 (96%) of 140 patients, there was complete resolution of the abscess following transgluteal drainage, without subsequent surgery. In six of 140 (4%) patients, incomplete resolution necessitated subsequent surgery for postoperative fluid collection (n = 3), diverticulitis (n = 2), or perforating appendicitis (n = 1). Complications of transgluteal drainage were rare and included hemorrhage in three (2%) of the 140 patients. There was no procedure-related mortality. A transpiriformis approach was significantly more likely to be associated with postprocedural pain (P <.001) than was an infrapiriformis approach. CONCLUSION: Percutaneous CT-guided transgluteal drainage is a safe and effective alternative to surgery for deep pelvic abscesses. Major complications are rare.

Abscess↗
PubMed2003

Noninvasive detection of clinically occult lymph-node metastases in prostate cancer.

BACKGROUND: Accurate detection of lymph-node metastases in prostate cancer is an essential component of the approach to treatment. We investigated whether highly lymphotropic superparamagnetic nanoparticles, which gain access to lymph nodes by means of interstitial-lymphatic fluid transport, could be used in conjunction with high-resolution magnetic resonance imaging (MRI) to reveal small nodal metastases. METHODS: Eighty patients with presurgical clinical stage T1, T2, or T3 prostate cancer who underwent surgical lymph-node resection or biopsy were enrolled. All patients were examined by MRI before and 24 hours after the intravenous administration of lymphotropic superparamagnetic nanoparticles (2.6 mg of iron per kilogram of body weight). The imaging results were correlated with histopathological findings. RESULTS: Of the 334 lymph nodes that underwent resection or biopsy, 63 (18.9 percent) from 33 patients (41 percent) had histopathologically detected metastases. Of these 63 nodes, 45 (71.4 percent) did not fulfill the usual imaging criteria for malignancy. MRI with lymphotropic superparamagnetic nanoparticles correctly identified all patients with nodal metastases, and a node-by-node analysis had a significantly higher sensitivity than conventional MRI (90.5 percent vs. 35.4 percent, P<0.001) or nomograms. CONCLUSIONS: High-resolution MRI with magnetic nanoparticles allows the detection of small and otherwise undetectable lymph-node metastases in patients with prostate cancer.

Aged↗
PubMed2003

Low-dose CT of the abdomen: evaluation of image improvement with use of noise reduction filters pilot study.

A prospective assessment of improvement in image quality at low-radiation-dose computed tomography (CT) of the abdomen by using noise reduction filters was performed. CT images acquired at standard and 50% reduced tube current were processed with six noise reduction filters and evaluated by three radiologists for image noise, sharpness, contrast, and overall image quality in terms of abdominal organ depiction. Quantitative image noise and contrast-to-noise ratio were measured. Baseline low-dose CT images were significantly worse than standard-dose CT images (P <.05). A statistically significant reduction of noise in low-dose images processed with three filters was noted. In conclusion, use of noise reduction filters decreased image noise at low-dose CT.

Aged↗
PubMed2003

CT colonography: digital subtraction bowel cleansing with mucosal reconstruction initial observations.

The authors evaluated a computed tomography (CT) colonographic technique with a combination of preexamination orally ingested positive contrast material and postacquisition image processing to subtract out the ingested opacified bowel contents. With this technique, rigorous physical purging of the bowel was not necessary before structural examination of the colon. With images obtained in 20 patients, two readers were able to correctly identify the majority of polyps confirmed at colonoscopy. Their performance for detection of lesions larger than 1 cm was similar to that with conventional CT colonography.

Administration, Oral↗
PubMed2003

Imaging of rectal cancer.

Radiologic evaluation of rectal cancer is invaluable in aiding the surgeon, gastroenterologist, and oncologist in the initial and follow-up management of patients with this malignancy. This review highlights recent developments in computed tomography; ultrasonographic, metabolic, and magnetic resonance imaging of rectal cancer; its clinical ramifications; and the direction of future efforts.

Endosonography↗
PubMed2003

Evaluation of simethicone-coated cellulose as a negative oral contrast agent for abdominal CT.

RATIONALE AND OBJECTIVES: Because of the increased clinical use of computed tomography (CT) for imaging the abdominal vasculature and urinary tract, there is a need for negative contrast agents. The authors undertook this study to assess the suitability of simethicone-coated cellulose (SCC), which is approved for use as an oral contrast agent in sonography, for use as a negative oral contrast agent in abdominal CT. MATERIALS AND METHODS: This prospective study involved 40 adult patients scheduled to undergo abdominal CT for the evaluation of hematuria. Prior to scanning, 20 subjects received 800 mL of SCC and 20 received 800 mL of water as an oral contrast agent. Imaging was performed with a multi-detector row helical scanner in two phases, according to the abdominal CT protocol used for hematuria evaluation at the authors' institution. The first, "early" phase began an average of 15 minutes after the ingestion of contrast material; the second, "late" phase began an average of 45 minutes after the ingestion of contrast material. Blinded analysis was performed by three abdominal radiologists separately, using a three-point scale (0 = poor, 1 = acceptable, 2 = excellent) to assess the effectiveness of SCC for marking the proximal, middle, and distal small bowel. Average scores for enhancement with SCC and with water were obtained and compared. Statistical analysis was performed with a Wilcoxon signed-rank test. RESULTS: SCC was assigned higher mean scores than water for enhancement in each segment of the bowel, both on early-phase images (0.8-1.35 for SCC vs 0.6-1.1 for water) and on late-phase images (1.1-1.4 vs 0.81-0.96). Bowel marking with SCC, particularly in the jejunum and ileum, also was rated better than that with water in a high percentage of patients. The differences between the scores for water and for SCC, however, were not statistically significant (P > .05). CONCLUSION: SCC is effective as a negative oral contrast agent for small bowel marking at CT.

Administration, Oral↗
PubMed2003

Low-density pheochromocytoma on CT: a mimicker of adrenal adenoma.

OBJECTIVE: Attenuation values on CT of less than 10 H are considered characteristic of adrenal adenomas. Adrenal pheochromocytomas can infrequently contain fat that could result in low attenuation on CT. The purpose of our study was to determine if pheochromocytomas could be confused with adenomas by virtue of their attenuation values on unenhanced CT. MATERIALS AND METHODS: CT attenuation and size of nine adrenal nodules producing pheochromocytoma syndrome were measured on unenhanced CT in nine patients. For five patients who received IV contrast material, washout profiles were also calculated. RESULTS: Two of the nine patients had adrenal lesions with attenuation values of less than 10 H; one had a pheochromocytoma with an attentuation of 9.0 H, and the other had a medullary hyperplasia with an attenuation of 1.8 H. These two nodules showed evidence of microscopic fat at histologic examination. No macroscopic fat was seen on the CT scans. The remaining seven patients had lesions with attenuation values exceeding 10 H (mean value, 25.6 H; range, 1.8-41 H). Mean diameter of the nine tumors (including the hyperplastic nodule) was 3.2 cm (range, 0.8-6.7 cm; SD, +/- 2.3 cm). The two low-attenuation lesions also mimicked adenomas by displaying more than 60% contrast washout on 10-min-delayed contrast-enhanced scans, unlike the other three pheochromocytomas for which we had washout data. CONCLUSION: On CT, pheochromocytomas may have attenuation values less than 10 H and also may display more than 60% washout of contrast agents on delayed scanning. Adrenal pheochromocytomas should be included with adenomas in the differential diagnosis both for masses with low attenuation on unenhanced CT and for lesions exhibiting a high percentage of contrast washout.

Adenoma↗
PubMed2002

Pancreatic tissue sampling guided by EUS, CT/US, and surgery: a comparison of sensitivity and specificity.

BACKGROUND: Needle aspiration of the pancreas is performed to differentiate pancreatic malignancy, focal chronic pancreatitis, and metastasis to the pancreas. Biopsies may be directed by using EUS, CT, US, or surgery. This study retrospectively compared the accuracy of EUS-guided, CT/US-guided, and surgical tissue sampling of the pancreas over a 5-year period. METHODS: The records of patients undergoing pancreatic tissue sampling were reviewed for a final clinical diagnosis based on the results of cytology, histology, and clinical history. The sensitivity, specificity, and accuracy of each technique were calculated. RESULTS: One hundred forty-nine tissue samples (68 EUS-guided, 70 CT/US-guided, 11 surgical) from 128 patients were compared. There was no significant difference in accuracy rates for EUS (76.4%), CT/US (81.4%), and surgically guided (81.8%) specimens. EUS was used when masses were smaller (2.6 +/- 0.1 cm) as compared with CT/US (3.4 +/- 0.2 cm, p < 0.001) and surgery (2.9 +/- 0.4 cm, p = 0.49). In univariate analyses, factors associated with greater accuracy regardless of technique were as follows: (1) older age, (2) larger size of the mass, and (3) participation by a cytologist during the procedure. A subsequent multivariate logistic regression analysis, in which the examination of the effect of each factor controls for the effect of each of the other factors, found that only older age was a significant predictor of accuracy. CONCLUSION: EUS-guided tissue sampling of pancreatic masses is as accurate as CT/US-guided sampling and surgical biopsies.

Age Factors↗
PubMed2002

Computed tomography and magnetic resonance imaging evaluation of liver cancer.

Focal liver lesions occur commonly and with varying histology, each requiring radically different management. There are a multitude of imaging modalities currently being used for detecting and characterizing focal liver neoplasms. The primary modalities include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and rarely, angiography. CT and MRI have benefited from rapid technologic advances, and MRI, in particular, from the advent of new contrast agents.

Adenoma, Liver Cell↗