Screening for pancreatic cancer in high-risk individuals using MRI: optimization of scan techniques to detect small lesions

Pancreatic cancer has a dismal prognosis in the general population. However, early detection and treatment of disease in high-risk individuals can improve survival, as patients with localized disease and especially patients with lesions smaller than 10 mm show greatly improved 5-year survival rates. To achieve early detection through MRI surveillance programs, optimization of imaging is required. Advances in MRI technologies in both hardware and software over the years have enabled reliable detection of pancreatic cancer at a small size and early stage. Standardization of dedicated imaging protocols for the pancreas are still lacking. In this review we discuss state of the art scan techniques, sequences, reduction of artifacts and imaging strategies that enable early detection of lesions. Furthermore, we present the imaging features of small pancreatic cancers from a large cohort of high-risk individuals. Refinement of MRI techniques, increased scan quality and the use of artificial intelligence may further improve early detection and the prognosis of pancreatic cancer in a screening setting.

Practice variation in venous resection during pancreatoduodenectomy for pancreatic cancer: A nationwide cohort study

BACKGROUND

Practice variation exists in venous resection during pancreatoduodenectomy, but little is known about the potential causes and consequences as large studies are lacking. This study explores the potential causes and consequences of practice variation in venous resection during pancreatoduodenectomy for pancreatic cancer in the Netherlands.

METHODS

This nationwide retrospective cohort study included patients undergoing pancreatoduodenectomy for pancreatic cancer in 18 centers from 2013 through 2017.

RESULTS

Among 1,311 patients undergoing pancreatoduodenectomy, 351 (27%) had a venous resection, and the overall median annual center volume of venous resection was 4. No association was found between the center volume of pancreatoduodenectomy and the rate of venous resections, nor between patient and tumor characteristics and the rate of venous resections per center. Female sex, lower body mass index, neoadjuvant therapy, venous involvement, and stenosis on imaging were predictive for venous resection. Adjusted for these factors, 3 centers performed significantly more, and 3 centers performed significantly fewer venous resections than expected. In patients with venous resection, significantly less major morbidity (22% vs 38%) and longer overall survival (median 16 vs 12 months) were observed in centers with an above-median annual volume of venous resections (>4).

CONCLUSION

Patient and tumor characteristics did not explain significant practice variation between centers in the Netherlands in venous resection during pancreatoduodenectomy for pancreatic cancer. The clinical outcomes of venous resection might be related to the volume of the procedure.

Feasibility of In Vivo Metal Artifact Reduction in Contrast-Enhanced Dedicated Spiral Breast Computed Tomography

BACKGROUND

Radiopaque breast markers cause artifacts in dedicated spiral breast-computed tomography (SBCT). This study investigates the extent of artifacts in different marker types and the feasibility of reducing artifacts through a metal artifact reduction (MAR) algorithm.

METHODS

The pilot study included 18 women who underwent contrast-enhanced SBCT. In total, 20 markers of 4 different types were analyzed for artifacts. The extent of artifacts with and without MAR was measured via the consensus of two readers. Image noise was quantitatively evaluated, and the effect of MAR on the detectability of breast lesions was evaluated on a 3-point Likert scale.

RESULTS

Breast markers caused significant artifacts that impaired image quality and the detectability of lesions. MAR decreased artifact size in all analyzed cases, even in cases with multiple markers in a single slice. The median length of in-plain artifacts significantly decreased from 31 mm (range 11-51 mm) in uncorrected to 2 mm (range 1-5 mm) in corrected images (p ≤ 0.05). Artifact size was dependent on marker size. Image noise in slices affected by artifacts was significantly lower in corrected (13.6 ± 2.2 HU) than in uncorrected images (19.2 ± 6.8 HU, p ≤ 0.05). MAR improved the detectability of lesions affected by artifacts in 5 out of 11 cases.

CONCLUSION

MAR is feasible in SBCT and improves the image quality and detectability of lesions.

Venous wedge and segment resection during pancreatoduodenectomy for pancreatic cancer: impact on short- and long-term outcomes in a nationwide cohort analysis

BACKGROUND

Venous resection of the superior mesenteric or portal vein is increasingly performed in pancreatic cancer surgery, whereas results of studies on short- and long-term outcomes are contradictory. The aim of this study was to evaluate the impact of the type of venous resection in pancreatoduodenectomy for pancreatic cancer on postoperative morbidity and overall survival.

METHODS

This nationwide retrospective cohort study included all patients who underwent pancreatoduodenectomy for pancreatic cancer in 18 centres (2013-2017).

RESULTS

A total of 1311 patients were included, of whom 17 per cent underwent wedge resection and 10 per cent segmental resection. Patients with segmental resection had higher rates of major morbidity (39 versus 20 versus 23 per cent, respectively; P < 0.001) and portal or superior mesenteric vein thrombosis (18 versus 5 versus 1 per cent, respectively; P < 0.001) and worse overall survival (median 12 versus 16 versus 20 months, respectively; P < 0.001), compared to patients with wedge resection and those without venous resection. Multivariable analysis showed patients with segmental resection, but not those who had wedge resection, had higher rates of major morbidity (odds ratio = 1.93, 95 per cent c.i. 1.20 to 3.11) and worse overall survival (hazard ratio = 1.40, 95 per cent c.i. 1.10 to 1.78), compared to patients without venous resection. Among patients who received neoadjuvant therapy, there was no difference in overall survival among patients with segmental and wedge resection and those without venous resection (median 32 versus 25 versus 33 months, respectively; P = 0.470), although there was a difference in major morbidity rates (52 versus 19 versus 21 per cent, respectively; P  = 0.012).

CONCLUSION

In pancreatic surgery, the short- and long-term outcomes are worse in patients with venous segmental resection, compared to patients with wedge resection and those without venous resection.

Surgical management and pathological assessment of pancreatoduodenectomy with venous resection: an international survey among surgeons and pathologists

BACKGROUND

The aim of this survey was to gain insights in the current surgical management and pathological assessment of pancreatoduodenectomy with portal-superior mesenteric vein resection (VR).

METHODS

A systematic literature search was performed to identify international expert surgeons (N = 150) and pathologists (N = 40) who published relevant studies between 2009 and 2019. These experts and Dutch surgeons (N = 17) and pathologists (N = 20) were approached to complete an online survey.

RESULTS

Overall, 76 (46%) surgeons and 37 (62%) pathologists completed the survey. Most surgeons (71%) estimated that preoperative imaging corresponded correctly with intraoperative findings of venous involvement in 50-75% of patients. An increased complication risk following VR was expected by 55% of surgeons, mainly after Type 4 (segmental resection-venous conduit anastomosis). Most surgeons (61%) preferred Type 3 (segmental resection-primary anastomosis). Most surgeons (75%) always perform the VR themselves. Standard postoperative imaging for patency control was performed by 54% of surgeons and 39% adjusted thromboprophylaxis following VR. Most pathologists (76%) always assessed tumor infiltration in the resected vein and only 54% of pathologists always assess the resection margins of the vein itself. Variation in assessment of tumor infiltration depth was observed.

CONCLUSION

This international survey showed variation in the surgical management and pathological assessment of pancreatoduodenectomy with venous involvement. This highlights the lack of evidence and emphasizes the need for research on imaging modalities to improve patient selection for VR, surgical techniques, postoperative management and standardization of the pathological assessment.

Correlation of the tumour-stroma ratio with diffusion weighted MRI in rectal cancer

OBJECTIVE

This study evaluated the correlation between intratumoural stroma proportion, expressed as tumour-stroma ratio (TSR), and apparent diffusion coefficient (ADC) values in patients with rectal cancer.

METHODS

This multicentre retrospective study included all consecutive patients with rectal cancer, diagnostically confirmed by biopsy and MRI. The training cohort (LUMC, Netherlands) included 33 patients and the validation cohort (VHIO, Spain) 69 patients. Two observers measured the mean and minimum ADCs based on single-slice and whole-volume segmentations. The TSR was determined on diagnostic haematoxylin & eosin stained slides of rectal tumour biopsies. The correlation between TSR and ADC was assessed by Spearman correlation (r_s).

RESULTS

The ADC values between stroma-low and stroma-high tumours were not significantly different. Intra-class correlation (ICC) demonstrated a good level of agreement for the ADC measurements, ranging from 0.84-0.86 for single slice and 0.86-0.90 for the whole-volume protocol. No correlation was observed between the TSR and ADC values, with ADC_meanr_s= -0.162 (p= 0.38) and ADC_minr_s= 0.041 (p= 0.82) for the single-slice and r_s= -0.108 (p= 0.55) and r_s= 0.019 (p= 0.92) for the whole-volume measurements in the training cohort, respectively. Results from the validation cohort were consistent; ADC_meanr_s= -0.022 (p= 0.86) and ADC_minr_s = 0.049 (p= 0.69) for the single-slice and r_s= -0.064 (p= 0.59) and r_s= -0.063 (p= 0.61) for the whole-volume measurements.

CONCLUSIONS

Reproducibility of ADC values is good. Despite positive reports on the correlation between TSR and ADC values in other tumours, this could not be confirmed for rectal cancer.

Dilatation of the main pancreatic duct as first manifestation of small pancreatic ductal adenocarcinomas detected in a hereditary pancreatic cancer surveillance program

BACKGROUND

MRI surveillance in a cohort of CDKN2A-p16-Leiden mutation carriers with a 20% lifetime risk of PDAC led to increased resection rates and improved survival. Patients with screen-detected PDAC were evaluated for main pancreatic duct (MPD) abnormalities in this retrospective review.

METHODS

Since 2000 annual MRI and optional EUS was performed in mutation carriers. Data of patients with screen-detected PDAC was collected on gender, age at diagnosis, site of tumor, size, outcome of surgery, pathology findings and survival. All MRIs were re-evaluated for MPD abnormalities.

RESULTS

23 PDAC were detected in 22 (10%) of 217 mutation carriers, 10 (45%) males and 12 (55%) females. The mean age at diagnosis was 59.8 years (range 39.2-74.3 years). Revision of the MRI/MRCP revealed a lesion and dilatation of the MPD in 8 of the 22 patients. In 5 of 7 patients with PDAC detected during follow-up, the previous MRI showed MPD dilatation without evidence of tumor. The mean size of PDAC was 12.3 mm (range 5-19 mm). All tumors were resectable.

CONCLUSION

MPD dilation is common in patients with screen-detected PDAC. Abnormalities on MRI during surveillance of high-risk individuals requires intense follow-up or prompt treatment, as early treatment results in a better prognosis.

High Growth Rate of Pancreatic Ductal Adenocarcinoma in CDKN2A-p16-Leiden Mutation Carriers

CDKN2A-p16-Leiden mutation carriers have a 20% to 25% risk of developing pancreatic ductal adenocarcinoma (PDAC). Better understanding of the natural course of PDAC might allow the surveillance protocol to be improved. The aims of the study were to evaluate the role of cystic precursor lesions in the development of PDAC and to assess the growth rate. In 2000, a surveillance program was initiated, consisting of annual MRI in carriers of a CDKN2A-p16-Leiden mutation. The study cohort included 204 (42% male) patients. Cystic precursor lesions were found in 52 (25%) of 204 mutation carriers. Five (9.7%) of 52 mutation carriers with cystic lesions and 8 (7.0%) of 114 mutation carriers without cystic lesions developed PDAC (P = 0.56). Three of 6 patients with a cystic lesion of ≥10 mm developed PDAC. The median size of all incident PDAC detected between 9 and 12 months since the previous normal MRI was 15 mm, suggesting an annual growth rate of about 15 mm/year. In conclusion, our findings show that patients with and without a cystic lesions have a similar risk of PDAC. However, cystic precursor lesions between 10 and 20 mm increase the risk of PDAC substantially. In view of the large size of the screen-detected tumors, a shorter interval of screening might be recommended for all patients. Cancer Prev Res; 11(9); 551-6. ©2018 AACR.

Accuracy of MRI for treatment response assessment after taxane- and anthracycline-based neoadjuvant chemotherapy in HER2-negative breast cancer

BACKGROUND

Studies suggest that MRI is an accurate means for assessing tumor size after neoadjuvant chemotherapy (NAC). However, accuracy might be dependent on the receptor status of tumors. MRI accuracy for response assessment after homogenous NAC in a relative large group of patients with stage II/III HER2-negative breast cancer has not been reported before.

METHODS

250 patients from 26 hospitals received NAC (docetaxel, adriamycin and cyclophosphamide) in the context of the NEOZOTAC trial. MRI was done after 3 cycles and post-NAC. Imaging (RECIST 1.1) and pathological (Miller and Payne) responses were recorded. Accuracy measures were calculated and MRI and pathologically assessed tumor sizes were correlated. Tumor size over- and underestimation were quantified.

RESULTS

Accuracy of MRI for determining pathological complete response (pCR) was 76%. The ROC-curve of MRI response and pCR had an area under the curve value of 0.63 (95% C.I. 0.52-0.74). The correlation coefficient of MRI and histopathological tumor measurements was 0.46 (p < 0.001). Correlations were different for ER-positive (r = 0.40, p < 0.001) and ER-negative (r = 0.76, p < 0.001) breast tumors. MRI under- and overestimated the tumor size in 47% and 40% of all patients. In cases of substantial tumor size underestimation (>2 cm), surgical margins were more often tumor positive compared to the rest of the patients (33% vs.12%, p = 0.005).

CONCLUSION

MRI measurements correlated moderately with tumor size on the surgical specimen. Only in ER-negative breast tumors, MRI tumor sizes correlated sufficiently with residual tumor size on the pathological specimen. Therefore, post-NAC MRI should be interpreted with caution.

Addition of zoledronic acid to neoadjuvant chemotherapy does not enhance tumor response in patients with HER2-negative stage II/III breast cancer: the NEOZOTAC trial (BOOG 2010-01)

BACKGROUND

The role of zoledronic acid (ZA) when added to the neoadjuvant treatment of breast cancer (BC) in enhancing the clinical and pathological response of tumors is unclear. The effect of ZA on the antitumor effect of neoadjuvant chemotherapy has not prospectively been studied before.

PATIENTS AND METHODS

NEOZOTAC is a national, multicenter, randomized study comparing the efficacy of TAC (docetaxel, adriamycin and cyclophosphamide i.v.) followed by granulocyte colony-stimulating factor on day 2 with or without ZA 4 mg i.v. q 3 weeks inpatients withstage II/III, HER2-negative BC. We present data on the pathological complete response (pCR in breast and axilla), on clinical response using MRI, and toxicity. Post hoc subgroup analyses were undertaken to address the predictive value of menopausal status.

RESULTS

Addition of ZA to chemotherapy did not improve pCR rates (13.2% for TAC+ZA versus 13.3% for TAC). Postmenopausal women (N = 96) had a numerical benefit from ZA treatment (pCR 14.0% for TAC+ZA versus 8.7% for TAC, P = 0.42). Clinical objective response did not differ between treatment arms (72.9% versus 73.7%). There was no difference in grade III/IV toxicity between treatment arms.

CONCLUSIONS

Addition of ZA to neoadjuvant chemotherapy did not improve pathological or clinical response to chemotherapy. Further investigations are warranted in postmenopausal women with BC, since this subgroup might benefit from ZA treatment.

NEOZOTAC: Efficacy results from a phase III randomized trial with neoadjuvant chemotherapy (TAC) with or without zoledronic acid for patients with HER2-negative large resectable or stage II or III breast cancer (BC)—A Dutch Breast Cancer Trialists’ Group (BOOG) study

1028

Background: The role of bisphosphonates when added to the neoadjuvant treatment of BC in enhancing the efficacy of therapy is still unknown. Methods: NEOZOTAC is a national, multicenter, randomized study comparing the efficacy of TAC (docetaxel, Adriamycin and cyclophosphamide i.v.) CT followed by G-CSF on day 2 with or without ZA 4 mg i.v. ,q 3 weeks in patients (pts) with stage II/III, measurable, HER2-negative BC and absence of prior bisphosphonate usage. The primary endpoint is the pathologic complete response (pCR) rate in the resection specimen and positive lymph nodes. 228 pts are needed to show an improvement of the pCR rates from 17% to 34% in the experimental arm using a 5% significance level based on the two-sided Fisher’s exact test with a power of 80%. Randomization was done by using the Pocock’s minimisation technique stratified by cT, cN and estrogen receptor status. pCR rate was analyzed using the Cochran-Mantel-Haenszel test, adjusting for the stratification factors. Analysis was based on intent-to-treat. An unplanned subgroup analysis of postmenopausal women (PMW; FSH >20 and estradiol <110) and baseline vitamin D levels was performed. Results: From July 2010 to April 2012, 250 patients from 25 participating sites were randomized. Pathologic response data of 228 patients are currently available. pCR rate did not differ between the two study arms (17% vs 16%, p = 0.81). However, a trend in benefit in favor of ZA was observed in PMW (18% vs 11%, OR 1.90, 95% C.I. 0.52 – 6.88). Patients with severe vitamin D insufficiency (<25 nmol/L) seemed to respond worse to CT numerically (6% vs. 18%). At ASCO pCR and clinical response data of all patients will be reported. Conclusions: Previously, we have shown that adding ZA to neoadjuvant CT is safe with good compliance.In this study, treatment with ZA did not result in a pCR benefit in the total study population. However our findings suggest that addition of ZA to neoadjuvant CT might be effective for enhancing response in PMW with BC. Clinical trial information: NCT01099436.

Multicenter, double-blind, randomized, intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine for MR angiography of peripheral arteries

PURPOSE

To prospectively compare the image quality and diagnostic performance achieved with doses of gadobenate dimeglumine and gadopentetate dimeglumine of 0.1 mmol per kilogram of body weight in patients undergoing contrast material-enhanced magnetic resonance (MR) angiography of the pelvis, thigh, and lower-leg (excluding foot) for suspected or known peripheral arterial occlusive disease.

MATERIALS AND METHODS

Institutional review board approval was granted from each center and informed written consent was obtained from all patients. Between November 2006 and January 2008, 96 patients (62 men, 34 women; mean age, 63.7 years +/- 10.4 [standard deviation]; range, 39-86 years) underwent two identical examinations at 1.5 T by using three-dimensional spoiled gradient-echo sequences and randomized 0.1-mmol/kg doses of each agent. Images were evaluated on-site for technical adequacy and quality of vessel visualization and offsite by three independent blinded readers for anatomic delineation and detection/exclusion of pathologic features. Comparative diagnostic performance was determined in 31 patients who underwent digital subtraction angiography. Data were analyzed by using the Wilcoxon signed-rank, McNemar, and Wald tests. Interreader agreement was determined by using generalized kappa statistics. Differences in quantitative contrast enhancement were assessed and a safety evaluation was performed.

RESULTS

Ninety-two patients received both agents. Significantly better performance (P < .0001; all evaluations) with gadobenate dimeglumine was noted on-site for technical adequacy and vessel visualization quality and offsite for anatomic delineation and detection/exclusion of pathologic features. Contrast enhancement (P < or = .0001) and detection of clinically relevant disease (P < or = .0028) were significantly improved with gadobenate dimeglumine. Interreader agreement for stenosis detection and grading was good to excellent (kappa = 0.749 and 0.805, respectively). Mild adverse events were reported for four (six events) and five (eight events) patients after gadobenate dimeglumine and gadopentetate dimeglumine, respectively.

CONCLUSION

Higher-quality vessel visualization, greater contrast enhancement, fewer technical failures, and improved diagnostic performance are obtained with gadobenate dimeglumine, relative to gadopentetate dimeglumine, when compared intraindividually at 0.1-mmol/kg doses in patients undergoing contrast-enhanced MR angiography for suspected peripheral arterial occlusive disease.

Intraplacental choriocarcinoma as an unexpected cause of intrauterine death at term

Intraplacental choriocarcinoma is rare. It can cause fetal death at term by fetomaternal hemorrhage. We present a case of intraplacental choriocarcinoma. After a hydatidiform mole with persistence of throphoblastic disease, the patient delivered a stillborn baby at term. Massive fetomaternal hemorrhage was the unexpected cause of death. Choriocarcinoma was only diagnosed after pathologic revision of the placenta because of persistent high levels of serum hCG (human chorionic gonadotropin). Massive fetomaternal hemorrhage should alert the obstetrician and the pathologist to the possibility of choriocarcinoma arising from the placenta.

Functional Renal Volume: Quantitative Analysis at Gadolinium-enhanced MR Angiography—Feasibility Study in Healthy Potential Kidney Donors

PURPOSE

To assess the feasibility of quantifying functional renal volume with gadolinium-enhanced magnetic resonance (MR) angiography.

MATERIALS AND METHODS

Institutional review board approval was obtained, and all subjects gave informed consent. A contour-detection three-dimensional algorithm for determining renal volumes was developed. The method was validated in 18 cadaveric pig kidneys by measuring the water displacement caused by the kidneys. The kidney lengths and volumes in 19 consecutive potential kidney donors who underwent gadolinium-enhanced MR angiography of the renal arteries also were determined. Differences in volume measurements between men and women and between left and right kidneys were analyzed by using the Student t test. The volume of perfused renal cortex was calculated by extracting voxels on the basis of the cortex signal intensity threshold. The relevance of renal function parameters--namely, creatinine clearance rates--in the donor candidates was assessed by using a linear regression model. Intra- and interobserver variabilities of the measurements were determined by using the Bland-Altman method.

RESULTS

Volume measurements of the cadaveric pig kidneys obtained by using MR angiography and the water displacement method were strongly correlated (r = 0.99). The mean total renal volume in the donor candidates was 196 mL (range, 136-295 mL). No significant differences in total renal volume between the men and women or between the left and right kidneys were found. The correlation between calculated renal cortex volumes (mean, 67 mL; range, 40-105 mL) and creatinine clearance rates was good (r = 0.69). Inter- and intraobserver variabilities were lower than 7%.

CONCLUSION

Quantification of functional renal volume with three-dimensional gadolinium-enhanced MR angiography seems feasible with use of the described semiautomatic method.

Gadobenate dimeglumine-enhanced MRI of the breast: analysis of dose response and comparison with gadopentetate dimeglumine

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy and dose response relationship of three doses of gadobenate dimeglumine for MRI of the breast and to compare the results with those obtained after a dose of 0.1 mmol/kg of body weight of gadopentetate dimeglumine. SUBJECTS AND METHODS. Gadobenate dimeglumine at 0.05, 0.1, or 0.2 mmol/kg of body weight or gadopentetate dimeglumine at 0.1 mmol/kg of body weight was administered by IV bolus injection to 189 patients with known or suspected breast cancer. Coronal three-dimensional T1-weighted gradient-echo images were acquired before and at 0, 2, 4, 6, and 8 min after the administration of the dose. Images were evaluated for lesion presence, location, size, morphology, enhancement pattern, conspicuity, and type. Lesion signal intensity-time curves were acquired, and lesion matching with on-site final diagnosis was performed. A determination of global lesion detection from unenhanced to contrast-enhanced and combined images was performed, and evaluations were made of the diagnostic accuracy for lesion detection and characterization. A full safety evaluation was conducted.

RESULTS

Significant dose-related increases in global lesion detection were noted for patients who received gadobenate dimeglumine (p < 0.04, all evaluations). The sensitivity for detection was comparable for 0.1 and 0.2 mmol/kg of gadobenate dimeglumine, and specificity was highest with the 0.1 mmol/kg dose. Higher detection scores and higher sensitivity values for lesion characterization were found for 0.1 mmol/kg of gadobenate dimeglumine compared with 0.1 mmol/kg of gadopentetate dimeglumine, although more variable specificity values were obtained. No differences in safety were observed, and no serious adverse events were reported.

CONCLUSION

Gadobenate dimeglumine is a capable diagnostic agent for MRI of the breast. Although preliminary, our results suggest that 0.1 mmol/kg of gadobenate dimeglumine may offer advantages over doses of 0.05 and 0.2 mmol/kg of gadobenate dimeglumine and 0.1 mmol/kg of gadopentetate dimeglumine for breast lesion detection and characterization.

Gadobenate dimeglumine-enhanced magnetic resonance angiography of the pelvic arteries

RATIONALE AND OBJECTIVES

To evaluate 4 doses of gadobenate dimeglumine (Gd-BOPTA) for contrast-enhanced magnetic resonance angiography (CE-MRA) of the pelvic arteries and to compare CE-MRA with unenhanced time-of-flight MRA (2D-TOF-MRA).

METHODS

A multicenter Phase II dose-finding study was performed in 136 patients with Gd-BOPTA doses of 0.025, 0.05, 0.1, and 0.2 mmol/kg bodyweight. Evaluation of CE-MRA images and comparison with 2D-TOF-MRA images was performed onsite and by 2 blinded offsite reviewers in terms of subjective image quality, number of lesions detected, and confidence in lesion characterization.

RESULTS

Significant (P < 0.05) improvements over unenhanced findings were observed for CE-MRA at all dose levels. For reviewer 1 and the onsite investigators, the overall image quality increased up to a dose of 0.1 mmol/kg and then plateaued. For reviewer 2, increased image quality was noted up to a dose of 0.2 mmol/kg. Significant (P < 0.005) increases in diagnostic confidence on CE-MRA versus unenhanced MRA was observed for all dose groups by reviewer 1 and the onsite investigators and for the 0.1 and 0.2 mmol/kg dose groups by reviewer 2. No serious adverse events were recorded that were attributable to the study drug and no trends in laboratory parameters, vital signs, or electrocardiogram recordings were observed.

CONCLUSIONS

Gadobenate dimeglumine-enhanced MRA is safe and significantly more effective than unenhanced 2D-TOF-MRA for imaging the pelvic arteries. A dose of 0.1 mmol/kg appears the most appropriate dose for subsequent Phase III clinical evaluation.

Gadobenate dimeglumine-enhanced MR angiography of the abdominal aorta and renal arteries

OBJECTIVE

This study was conducted to determine the efficacy and safety of four different doses of gadobenate dimeglumine for contrast-enhanced three-dimensional MR angiography of the abdominal aorta and renal arteries.

SUBJECTS AND METHODS

Ninety-four patients with suspected abnormality of the abdominal aorta or renal arteries underwent unenhanced three-dimensional gradient-recalled echo time-of-flight MR angiography and contrast-enhanced MR angiography after the IV injection of one of four doses of gadobenate dimeglumine (0.025, 0.05, 0.1, and 0.2 mmol/kg of body weight). Efficacy was assessed on-site and by two blinded off-site reviewers in terms of change in total diagnostic quality score and diagnostic quality score per vessel segment from baseline unenhanced time-of-flight MR angiography to contrast-enhanced MR angiography. Secondary efficacy end points included lesion count and level of confidence in lesion characterization. Safety assessments comprised adverse event monitoring, physical evaluation, vital signs, ECG, and laboratory investigations.

RESULTS

A significant change in the total diagnostic quality score from unenhanced to contrast-enhanced MR angiography was observed at all doses. The change increased with increased dose, plateauing at the 0.1 mmol/kg dose level. More patients with lesions detected and increased reviewer confidence for lesion characterization were noted on contrast-enhanced MR angiography compared with unenhanced MR angiography, although no dose-related trends were observed. All doses were well tolerated, and no significant changes in safety parameters were observed.

CONCLUSION

Gadobenate dimeglumine is an effective and safe agent for contrast-enhanced MR angiography of the abdominal aorta and renal arteries. A dose of 0.1 mmol/kg of body weight appears to be the most suitable.

Chronic splanchnic ischaemia

Chronic splanchnic ischaemia is a relatively unusual clinical entity consisting of pain and/or weight loss and caused by chronic splanchnic disease (i.e. stenosis and/or occlusion of the coeliac and superior mesenteric artery). The occlusive disease is usually caused by atherosclerosis and is in itself not rare in older individuals. Extensive collateral circulation can develop between the three splanchnic arteries and may compensate for the decreased splanchnic perfusion over time. The pathophysiology of chronic splanchnic ischaemia has still not been completely elucidated.A reliable diagnosis of chronic splanchnic ischaemia, based on a proven causal relationship between the occlusive disease and the symptoms, can be very difficult. Traditionally, tests for evaluating the haemodynamic consequences of the vascular stenoses were not available. Important improvements in establishing a more reliable diagnosis have been achieved with duplex ultrasound and magnetic resonance evaluation of the splanchnic circulation. Tonometry is another promising functional test that may prove useful not only for gaining greater insight into the pathophysiology of chronic splanchnic ischaemia but also for the clinical evaluation of this syndrome. The natural history of chronic splanchnic disease suggests that progressive disease may result in acute mesenteric ischaemia. Surgical reconstruction of the coeliac and/or the superior mesenteric artery is the therapeutic standard with excellent short and long-term results. Satisfactory early results using angioplasty with or without stent suggest that this type of intervention may relieve symptoms in selected patients with a higher surgical risk.

MR angiography of the intracranial venous system

PURPOSE

To compare the effectiveness of different imaging planes at time-of-flight (TOF) magnetic resonance (MR) angiography and phase-contrast MR angiography in the visualization of the normal intracranial venous system.

MATERIALS AND METHODS

In 12 healthy volunteers, two-dimensional (2D) TOF MR angiography and three-dimensional (3D) phase-contrast MR angiography were performed in transverse, sagittal, and coronal planes. All data were displayed as maximum intensity projection (MIP) images. Four neuroradiologists assessed the visibility of 28 intracranial venous structures on the MIP images. Statistical analysis was performed by using the Friedman two-way analysis of variance and the Cochran Q test.

RESULTS

Visualization of the normal intracranial venous system was better with 3D phase-contrast and coronal 2D TOF MR angiography than with transverse or sagittal 2D TOF MR angiography (P < .05, Friedman test) for each observer and the group of observers. Differences were found between each of the 2D TOF and 3D phase-contrast MR angiographic sequences in the visualization of individual venous structures (Cochran Q test). The kappa values ranged from 0.36 to 0.71, which indicated a moderate to good agreement between observers.

CONCLUSION

The normal intracranial venous system is adequately visualized with 3D phase-contrast and coronal 2D TOF MR angiography.

Vascularization of head and neck paragangliomas: comparison of three MR angiographic techniques with digital subtraction angiography

BACKGROUND AND PURPOSE

MR angiography of the head and neck region has been studied widely, but few studies have been performed concerning the efficacy of MR angiography for the identification of the specific vascular supply of the highly vascular head and neck paragangliomas. In this study, we compared three MR angiography techniques with respect to visualization of branch arteries in the neck and identification of tumor feeders in patients with paragangliomas.

METHODS

Fourteen patients with 29 paragangliomas were examined at 1.5 T using 3D phase-contrast (PC), 2D time-of-flight (2D TOF), and multi-slab 3D TOF MR angiography. In the first part of the study, two radiologists independently evaluated the visibility of first-, second-, and third-order branch arteries in the neck. In the second part of the study, the number of feeding arteries for every paraganglioma was determined and compared with digital subtraction angiography (DSA), the standard of reference in this study.

RESULTS

Three-dimensional TOF angiography was superior to the other MR angiography techniques studied (P < .05) for depicting branch arteries of the external carotid artery in the neck, but only first- and second-order vessels were reliably shown. DSA showed a total of 78 feeding arteries in the group of patients with 29 paragangliomas, which was superior to what was revealed by all MR angiography techniques studied. More tumor feeders were identified with 3D TOF and 2D TOF angiography than with 3D PC MR angiography (P < .05), with a sensitivity/specificity of 61%/98%, 54%/95%, and 31%/95%, respectively. Sensitivity was lowest for carotid body tumors.

CONCLUSION

Compared with intra-arterial DSA, the 3D TOF MR angiography technique was superior to 3D PC and 2D TOF MR angiography for identifying the first- and second-order vessels in the neck. With 3D TOF angiography, more tumor feeders were identified than with the other MR angiography techniques studied. The sensitivity of MR angiography, however, is not high enough to reveal important vascularization. The sensitivity of MR angiography is too low to replace DSA, especially in the presence of carotid body tumors.

Vessel diameter measurements in gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries

In this study, the possibilities for quantification of vessel diameters of peripheral arteries in gadolinium contrast-enhanced magnetic resonance angiography (Gd CE MRA) were evaluated. Absolute vessel diameter measurements were assessed objectively and semi-automatically in maximum intensity projections (MIPs) of contrast-enhanced T1-weighted 3D spoiled gradient-echo datasets, studied with digital subtraction techniques. In vivo, the complete peripheral arterial bed of six patients was studied, from the aorto-iliac bifurcation down to the distal run-off. By measuring the signal intensity (SI) over the lumen of a vessel in the MIP, an SI-plot was obtained. Next, the vessel boundaries were determined using a threshold algorithm; from these boundary points individual diameter values could be obtained along the trajectory of the vessel. In an in vitro study, an optimal threshold value of 30% of the range of SI-values between the background and the maximal SI in the vessel was obtained for accurate diameter measurement in Gd CE MRA (i.e., full-width 30%-maximum). Furthermore, the relationship between the accuracy of these measurements and the scan resolution was investigated. Accuracy was found to be acceptable (i.e., less than 10% over/underestimation) for vessel sizes covering at least 3 pixels. In six patients, diameters were measured in MIPs of the total datasets (i.e., D(T)) as well as in selective MIPs of the clipped datasets (i.e., D(S)) (n = 209). D(T) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.98. Measurements in the total MIPs yielded statistically significant (p < 0.01) smaller diameter values compared with measurements in selective MIPs, with a mean difference of 0.15 mm. Diameter values from the selective MIPs of the aorto-iliac arteries were also compared with diameter values measured at corresponding anatomic positions in X-ray angiograms of these patients (i.e., D(x)) (n = 70). D(X) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.92. Diameters measured in the selective MIPs were smaller than those measured in the X-ray angiograms (mean difference 0.49 mm) and this difference was statistically significant (p < 0.01). In conclusion, diameter values can be evaluated accurately in MIPs of vessels with at least 3 pixels in diameter, using the full-width 30%-maximum criterion.

Stenosis quantification from post-stenotic signal loss in phase-contrast MRA datasets of flow phantoms and renal arteries

In this study a semi-automated and observer-independent algorithm for quantifying post-stenotic signal loss (PSL) in 3D phase-contrast (PC) magnetic resonance angiography (MRA) of patients with renal artery stenosis is presented. This algorithm was developed on MRA datasets of stenotic phantoms, which were included in a flow circuit with stationary flows. The length and the severity of the PSL (incorporating both length and degree of PSL) in the maximum intensity projections (MIPs) of MRA datasets were proposed for quantifying stenoses. The algorithm was tested in renal arteries of ten patients with renal artery stenosis and seven healthy volunteers. Digital subtraction angiography (DSA) was performed in the patients and served as the gold standard. Stenosis severity showed better correlation with the severity of the PSL than with the length, both for in vitro as in vivo. Spearman correlation coefficients (rS) showed statistically significant correlations between the severity of the PSL and parameters determined by DSA, i.e. percent diameter stenosis (rS = 0.90). The length of the PSL showed no correlation with the diameter stenosis (rS = 0.37).

Magnetic resonance angiography of peripheral vascular disease

Due to rapid developments in gradient and software technology, magnetic resonance angiography has become a routine clinical tool for imaging of blood vessels in the body. The introduction of contrast-enhanced 3D gradient echo techniques in particular has brought about a turning-point in the application of magnetic resonance angiography in daily clinical practice. This paper presents a brief overview of the various approaches to the application of magnetic resonance angiography for imaging of the peripheral vasculature, not only of the arteries, but also of the veins.

Gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries with multiple bolus injection: scan optimization in vitro and in vivo

In this study, a scanning protocol was developed to image the arterial bed of the pelvis and both legs along their entire length in patients with peripheral arterial disease, using standard hard- and software. Three adjacent stations are acquired consecutively, with some small overlap; per station; one Gadolinium contrast bolus is administered. The scanning protocol was optimized in an in vitro phantom study. The optimal flip angle was found to be 50 degrees. Also, the optimal scan delay was chosen to be equal to the arrival time of the contrast bolus thereby minimizing artifacts. Three contrast bolus injections showed sufficient enhancement of the vessels after image subtraction. Finally, stenosis quantification by manual caliper was performed by five observers in the MRA images and correlated with the percent diameter reduction determined by quantitative angiography from corresponding X-ray images. The results of the MRA measurements were reproducible and intra- and inter-observer variabilities were statistically non-significant (p = 0.54 and p = 0.12, respectively). Stenosis quantification performed by four observers showed a good correlation with the X-ray derived values (rp > 0.90, p < 0.02); the results from one observer were not significantly correlated. Five patients with proven peripheral disease were investigated with this new MRA scanning protocol. The images were of good quality which allowed adequate clinical evaluation; the original diagnoses obtained from X-ray examinations, were confirmed with MRA. In conclusion, peripheral arterial disease can be evaluated adequately with this MR scanning protocol.

Scan optimization of gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries with multiple bolus injections and in vitro validation of stenosis quantification

In this study, a T1-weighted three-dimensional (3D) spoiled gradient-echo scanning protocol was developed to image the complete arterial system of the pelvis and both legs along their entire length in patients with peripheral arterial disease. Three adjacent stations were to be acquired consecutively, with some overlap, to image the entire area of interest; per station one gadolinium (Gd) contrast bolus would be administered. In an in vitro phantom study, the scanning protocol was optimized. The optimal flip angle was found to be 50 degrees. Also, the optimal scan delay was chosen to be equal to the arrival time of the contrast bolus, thereby minimizing artifacts. Three contrast bolus injections showed sufficient enhancement of the vessels after image subtraction. Finally, stenosis quantification by manual caliper was performed by five observers in the magnetic resonance angiography (MRA) images and correlated with the percent diameter reduction determined by quantitative angiography from corresponding X-ray images. The MRA measurements were reproducible, and intra- and interobserver variabilities were statistically non-significant (p=0.54 and p=0.12, respectively). Stenosis quantification performed by four observers showed a good correlation with the X-ray-derived values (rp > 0.90, p < 0.02); the results from one observer were not significantly correlated. Five patients with proven peripheral disease were investigated with this new MRA scanning protocol, using standard hardware and software. The images were of good quality, which allowed adequate clinical evaluation; the original diagnoses obtained from X-ray examinations, were confirmed with MRA. In conclusion, peripheral arterial disease can be evaluated adequately with this magnetic resonance scanning protocol.

Activity of Crohn's disease assessed by measurement of superior mesenteric artery flow with Doppler ultrasound

PURPOSE

To investigate the value of superior mesenteric artery (SMA) Doppler flow measurements as a marker for disease activity in patients with Crohn's disease.

MATERIALS AND METHODS

Duplex Doppler sonographic measurements of SMA bloodflow volume were obtained in 90 patients with suspected or known Crohn's disease in three separate studies. The first study was a pilot study to ascertain the value of Doppler measurements in patients with proven active or inactive disease and to check our performance. In two following studies prospectively a correlation was sought between the independent assessment of Doppler flow measurements and our standard of reference based on clinical history, physical examination, laboratory values, endoscopy, surgery and/or follow-up and prospectively a correlation was sought between Doppler studies and the results of enteroclysis.

RESULTS

In all but two patients (study II) adequate measurements of SMA flow were obtained. In the active patient groups the Doppler SMA flow was significantly increased (P < 0.05) compared to the inactive patient groups and the control groups.

CONCLUSION

These studies show that SMA Doppler flow measurements can be used as a parameter to assess disease activity in patients with Crohn's disease.

Comparison of inversion-recovery gradient- and spin-echo and fast spin-echo techniques in the detection and characterization of liver lesions

PURPOSE

To compare respiratory-triggered inversion-recovery (IR) gradient- and spin-echo (GRASE) magnetic resonance (MR) imaging with respiratory-triggered T2-weighted fast spin-echo (SE) imaging in the diagnosis of liver metastases.

MATERIALS AND METHODS

In this prospective study, two radiologists independently identified focal hepatic lesions on respiratory-triggered IR GRASE and respiratory-triggered fast SE MR images in 28 consecutive patients with 186 (135 malignant and 51 benign) proved lesions. A combination of findings at surgery, intraoperative ultrasonography (US), and histologic examination served as the standard of reference. Contrast-to-noise ratios (CNRs) were obtained from 86 lesions larger than 10 mm.

RESULTS

The sensitivity in the detection of liver metastases was, independent of lesion size and observer, higher for IR GRASE imaging (55%) than for fast SE imaging (44%-50%) (observer 1, P = .014; observer 2, P = .21). Confidence levels with IR GRASE imaging were higher, but not significantly so, than those with fast SE imaging (P < .098). Both observers characterized liver lesions better with IR GRASE than with fast SE imaging (observer 1, P = .04; observer 2, P = .48). The metastasis-liver CNR was significantly higher (P = .012) with IR GRASE imaging.

CONCLUSION

The respiratory-triggered IR GRASE sequence is a fast alternative to the respiratory-triggered fast SE sequence in the evaluation of suspected liver metastases.

[Unconventional imaging techniques in inflammatory bowel diseases]

In patients with inflammatory bowel disease (IBD), radiologic examinations are important for diagnosis and treatment. With conventional X-ray examinations, mucosal abnormalities, ulcers and fistulas can be visualised, but no information on the extramural extension of the disease can be obtained. Newer radiologic modalities (ultrasound, CT and MRI) offer new diagnostic possibilities. With ultrasound IBD can be diagnosed with good confidence and it can differentiate between Crohn's disease and ulcerative colitis. CT and MRI are indicated not so much to diagnose the disease but rather to determine the severity and spread of disease activity (transmural and extramural inflammation) and to detect complications such as fistulas and abscesses.

Diagnostic imaging modalities for delayed renal graft function: a review

A varying percentage of cadaveric transplant recipients remain anuric or oliguric and depend on dialysis in the first weeks after transplantation. This delayed graft function group needs careful management to detect additional post-transplant events. Under these clinical circumstances, the assessment of allograft status depends to a great extent on non-invasive imaging studies. The wide variety of imaging procedures for the transplanted kidney, combined with recent technical advances in ultrasonography, scintigraphy and radiopharmaceuticals, computed tomography and magnetic resonance imaging, has created a challenging and sometimes confusing environment for clinicians, radiologists and nuclear medicine physicians. Assessing the relative merits of available procedures and choosing an optimal approach to the clinical presentation of a particular graft is sometimes difficult. The contrasting characteristics of these diagnostic methods led us to consider their relative roles and to determine their selective use. This review focuses on the value and limitations of diagnostic imaging modalities in the management of patients with impaired or delayed graft function. Our emphasis is on ultrasonography and nuclear medicine, as these are the most frequently used methods.

Variations in blood flow waveforms in stenotic renal arteries by 2D phase-contrast cine MRI

Waveform variations in blood flow measurements through stenotic renal arteries have been reported already with echo Doppler studies. We studied these variations with MRI in 14 patients (mean age, 60 years) with suspected renal arterial stenosis (24 patent arteries, four occluded). Flow measurements were successful in 15 arteries and unsuccessful in nine, due to practical limitations. Seven healthy younger volunteers (mean age, 28 years) and five healthy older volunteers (mean age, 58 years) were recruited for comparison purposes. In patients, the severity of stenoses was also assessed by digital subtraction angiography and intraarterially measured transstenotic pressure drops. We found flow patterns to be statistically significantly (P < 0.01) age-related. Younger healthy subjects showed shorter wave duration, higher diastolic flow, and total blood flow per minute. Also, with increasing stenosis severity, the systolic wave became more damped and the systolic wave duration became statistically significantly (P = .03) longer.

Objective stenosis quantification from post-stenotic signal loss in phase-contrast magnetic resonance angiographic datasets of flow phantoms and renal arteries

In this study a semi-automated and observer-independent algorithm for quantifying post-stenotic signal loss (PSL) in three-dimensional phase-contrast (PC) magnetic resonance angiography (MRA) of patients with renal artery stenosis is presented. This algorithm was developed on MRA datasets of stenotic phantoms, included in a flow circuit with stationary flows. The length and the severity of the PSL (incorporating both the length and the degree of PSL) in the MRA datasets were proposed for quantifying the stenoses. The algorithm was tested in renal arteries; ten patients with renal artery stenosis and seven healthy volunteers were investigated. Digital subtraction angiography was performed in the patients and served as the gold standard. Stenosis severity showed better correlation with the severity of the PSL than with the length, both for in vitro and in vivo measurements. Spearman correlation coefficients (rs) showed statistically significant correlations between the severity of the PSL and parameters determined by digital subtraction angiography, i.e., percent diameter stenosis (rs = 0.90). The length of the PSL showed no correlation with the diameter stenosis (rs = 0.37). In conclusion, this study presents a semi-automated and observer-independent way of quantifying signal loss, and the severity of the PSL is proposed for quantifying stenoses, rather than the length of PSL.

Diagnosis of Crohn's ileitis and monitoring of disease activity: value of Doppler ultrasound of superior mesenteric artery flow

OBJECTIVE

To assess the value of measurements of superior mesenteric artery flow using Doppler ultrasound for detecting disease activity in patients with proven or suspected Crohn's disease.

METHODS

Superior mesenteric artery flow was measured prospectively in 31 patients with known or suspected small-bowel disease. Sixteen patients were known to suffer from Crohn's disease and were suspected of having active disease. Fifteen patients had abdominal complaints without a specific diagnosis. Enteroclysis was used as the standard of reference to detect Crohn's disease, to define the location of small-bowel Crohn's disease, and to assess disease activity by demonstrating cobblestoning. Disease activity was further substantiated by clinical signs, laboratory values, and clinical follow-up.

RESULTS

Ten patients with active disease on enteroclysis made up group 1. Group 2 comprised nine patients known to have Crohn's disease but without active disease (inactive small-bowel disease). The remaining 12 patients made up group 3. In group 1, the flow volume values were significantly higher than those in group 2 and group 3: 738 +/- 411 (mean +/- SD) versus 364 +/- 101 and 300 +/- 91, respectively (p < 0.05).

CONCLUSIONS

Whereas the initial diagnosis of small-bowel involvement in Crohn's disease may rely on enteroclysis, Doppler measurements of superior mesenteric artery flow are useful to monitor the activity of Crohn's disease.

Doppler sonography evaluation of superior mesenteric artery flow to assess Crohn's disease activity: correlation with clinical evaluation, Crohn's disease activity index, and alpha 1-antitrypsin clearance in feces

OBJECTIVE

This study was undertaken to investigate the value of Doppler flow measurements of the superior mesenteric artery (SMA) as a marker for disease activity in patients with Crohn's disease.

SUBJECTS AND METHODS

Duplex Doppler sonography measurements of SMA blood flow volume were obtained in 29 consecutive patients with suspected Crohn's disease. We prospectively sought a correlation between the independent assessment of Doppler flow measurements and markers for disease activity: Crohn's disease activity index and fecal alpha 1-antitrypsin clearance and our reference standard based on clinical history, physical examination, laboratory values, endoscopy, surgery, and follow-up.

RESULTS

In 27 of 29 patients, adequate measurements of SMA blood flow were obtained. In 15 patients no disease activity was judged to be present or no Crohn's disease (n = 2) was found at follow-up (group 1). In 12 patients, activity of Crohn's disease was diagnosed (group 2) on the basis of the reference standard. In group 2 the Doppler SMA blood flow values were significantly higher (p < .05) than those for group 1 (826 +/- 407 ml/min versus 323 +/- 103 ml/min). Of the other parameters investigated, only the alpha 1-antitrypsin value correlated with the reference standard but to a lesser degree than the values for SMA blood flow measurement.

CONCLUSION

This prospective study shows that SMA Doppler blood flow measurements can be used to assess disease activity in patients with Crohn's disease. This approach may be of value in the diagnosis and follow-up of patients with Crohn's disease, providing directly available, quantifiable, noninvasive information on disease activity.

Variability of splanchnic blood flow measurements using MR velocity mapping under fasting and post-prandial conditions--comparison with echo-Doppler

BACKGROUND/AIMS

The aim was to study the reproducibility of magnetic resonance velocity mapping, when measuring portal vein and superior mesenteric artery blood flow, under fasting and post-prandial conditions. Magnetic resonance flow measurements for the portal vein were compared with echo-Doppler measurements in the right portal vein.

METHODS

Eight healthy volunteers were studied on two occasions, separated by 1 week. Blood flow in the portal vein and superior mesenteric artery was measured repeatedly under basal fasting conditions. On one occasion measurements were also made after a meal. Every magnetic resonance measurement was followed by an echo-Doppler measurement in the right portal vein. Correlations between flow values were calculated using Pearson's r. Variability components were assessed using ANOVA.

RESULTS

Intra-individual variability was approximately 7% for portal vein flow measurements using magnetic resonance velocity mapping. This variability did not increase after 1 h, 1 week and after a meal. Values of flow measured in the portal vein and superior mesenteric artery using magnetic resonance velocity mapping correlated well (r = 0.80, p < 0.001). Fasting portal flow as measured with magnetic resonance velocity mapping was 1.2 l/min (range 0.96-1.6 l/min). Variability in echo-Doppler measurements was comparable to the variability of magnetic resonance velocity mapping, and flow measurements obtained with the two techniques correlated well (r = 0.74; p < 0.001).

CONCLUSIONS

Magnetic resonance velocity mapping accurately measures blood flow in the portal vein with low variability and should be preferred when absolute flow values are necessary. Echo-Doppler measurement of the right portal vein has a low variability and can be used to study changes in flow.

Hemodynamic significance of renal artery stenosis: digital subtraction angiography versus systolically gated three-dimensional phase-contrast MR angiography

PURPOSE

To compare digital subtraction angiography with three-dimensional phase-contrast magnetic resonance (MR) angiography in detection of significant renal artery stenosis.

MATERIALS AND METHODS

Sixteen patients underwent digital subtraction angiography and systolically gated three-dimensional phase-contrast MR angiography within 1 week. Scoring of stenosis on MR angiograms was based on presence and length of a flow void and quality of flow signal intensity in the distal part of the artery. Intraarterial pressure measurement was the reference standard for hemodynamically significant renal artery stenosis.

RESULTS

MR angiography depicted two of five patent accessory arteries. Comparison of digital subtraction angiography and MR angiography with intraarterial pressure measurements was possible in 25 main renal arteries. In 13 arteries, a pressure gradient of more than 15 mm Hg was found. Digital subtraction angiography depicted 10 of these stenoses (sensitivity, 77%; specificity, 92%). A flow void was present at MR angiography in eight stenoses (sensitivity, 62%; specificity, 83%). In 12 of the stenosed vessels, distal flow signal intensity was impaired at MR angiography (sensitivity, 92%; specificity, 75%). There was no difference between the two modalities (P > .05) in grading hemodynamic significance of renal artery stenosis.

CONCLUSION

Systolically gated MR angiography and digital subtraction angiography are equally effective in depicting hemodynamically significant stenoses in the main renal arteries. MR angiography, however, is not adequate in depiction of accessory renal arteries.

Systolically gated 3D phase contrast MRA of mesenteric arteries in suspected mesenteric ischemia

OBJECTIVE

Our goal was to assess the value of MRA for detecting stenoses in the celiac (CA) and superior mesenteric (SMA) arteries in patients suspected of having chronic mesenteric ischemia, using an optimized systolically gated 3D phase contrast technique.

MATERIALS AND METHODS

In an initial study in 24 patients who underwent conventional angiography of the abdominal vessels for different clinical indications, a 3D phase contrast MRA technique (3D-PCA) was evaluated and optimized to image the CAs and SMAs. Subsequently, a prospective study was performed to assess the value of systolically gated 3D-PCA in evaluation of the mesenteric arteries in 10 patients with signs and symptoms of chronic mesenteric ischemia. Intraarterial digital subtraction angiography and surgical findings were used as the reference standard.

RESULTS

In the initial study, systolic gating appeared to be essential in imaging the SMA on 3D-PCA. In 10 patients suspected of mesenteric ischemia, systolically gated 3D-PCA identified significant proximal disease in the two mesenteric vessels in 4 patients. These patients underwent sucessful reconstruction of their stenotic vessels.

CONCLUSION

Cardiac-gated MRA may become a useful tool in selection of patients suspected of having mesenteric ischemia who may benefit from surgery.

Activity of Crohn disease assessed by measurement of superior mesenteric artery flow with Doppler US

PURPOSE

To test the hypothesis that increased blood flow in the superior mesenteric artery (SMA) reflects disease activity in patients with Crohn disease.

MATERIALS AND METHODS

Duplex Doppler sonographic measurements of SMA blood flow volume were obtained in 10 patients with active Crohn disease, 10 patients with chronic inactive Crohn disease, and 10 healthy volunteers. Disease activity was determined with clinical and laboratory indicators.

RESULTS

Interstudy reproducibility of repeated SMA flow volume measurements was good (r = .98). A marked increase in SMA flow volume was noted in patients with active disease compared with patients with inactive disease and healthy volunteers: 1,588 mL/min +/- 576 versus 288 mL/min +/- 113 and 417 mL/min +/- 147, respectively (P < .05 for both comparisons).

CONCLUSION

Activity of Crohn disease causes a substantial increase in SMA flow volume. Measurement of SMA blood flow may be an important noninvasive, readily available, inexpensive tool that can be used to monitor Crohn disease objectively.

Effects of an antifibrin monoclonal antibody and fragments thereof on some properties of fibrin

Antifibrin monoclonal antibody Y22, of IgG1-subclass, has its epitope in the D-domain of fibrin. In a thrombin time assay, Y22 and its F(ab)2 fragments interfere with clotting of citrated plasma. Transmission and scanning electronmicroscopic studies show that clotting of citrated blood or plasma in the presence of Y22 results in formation of thin, short fibrin fibres. The (smaller) Fab fragments of Y22 did not have an anti-clotting effect. This suggests that the anticoagulant effect of Y22 is due to steric hindrance of the association of fibrin monomers. A control antibody and its F(ab)2 and Fab fragments have no effect on fibrin formation. In a parabolic rate assay, Y22 Fab fragments interfered strongly with the fibrin-induced enhancement of the t-PA-catalyzed plasminogen activation, whereas intact Y22 and a control antibody did not. In contrast with their effects on the fibrin assembly, the effects of Y22, Y22-F(ab)2 and Y22-Fab on the capacity of fibrin to act as a rate-enhancer in the plasminogen activation by t-PA appears to decrease with the size of the immunoreactive entity. As is discussed, this may be due to the differential accessibility of sites involved in stimulation and polymerization which are located in the fibrin D-domain.

Thrombus detection using a Tc-99m labeled antifibrin monoclonal antibody (MoAb). Experiments in vitro and in animals

This paper describes the production and characterization of an antifibrin monoclonal antibody, produced by immunizing mice with fibrinogen degradation fragment Y. The antibody (designated Y22) is directed against a conformation dependent epitope in the D-domain of fibrin Y22 was labeled with the radionuclide Tc-99m. Experiments in vitro and in rats are presented which show the potential of scintigraphic detection of thrombi with Tc-99m-Y22. Preliminary results show that immunoscintigraphy of thrombi may also have potential for the monitoring of thrombolytic therapy (eg with t-PA).

Anaphylaxis as a rare complication of a barium enema examination

A patient is described who developed anaphylaxis with respiratory and circulatory arrest after a single contrast barium enema examination. Since barium sulphate is an inert substance, the reaction must have been caused by additives present in the barium suspension.

An in vitro model for the scintigraphic detection of thrombi using a 99Tcm-labelled antifibrin monoclonal antibody

Because of their specific targeting properties, monoclonal antibodies have found widespread use in nuclear medicine. In this paper, a method is described for the evaluation of immunoscintigraphic parameters for the detection of thrombi, using a 99Tcm-labelled antifibrin monoclonal antibody (designated as Y22). An in vitro model was developed to evaluate the effects of various environmental conditions on uptake by plasma clots of 99Tcm-Tc-Y22 in circulating plasma on a gamma camera. The clots became visible as hotspots after approximately 1 h of circulation of 99Tcm-Y22 containing citrated plasma at 37 degrees C. Circulation of 99Tcm-fibrinogen, 99Tcm-HSA or 99Tcm-control MoAb did not show visible uptake by the clots under the same conditions. At 37 degrees C, 99Tcm-Y22 accumulated approximately four times faster than at 20 degrees C. Heparin did not affect binding of the antibody to clots. To assess the feasibility of thrombus detection in vivo, an extracorporeal rat thrombus model was used. A thrombus in a shunt between a carotid artery and a jugular vein became visible 1 h after injection of the labelled Y22 and, more clearly, after 3 h.

An antifibrin monoclonal antibody useful in immunoscintigraphic detection of thrombi

Balb/c mice were immunized with human plasmin-generated fibrinogen degradation product Y. Spleen cells were fused with P3X63-Ag8.653 myeloma cells. A clone (Y22) was found that produces monoclonal antibodies (MoAbs) with a strong reactivity with human fibrin and only a weak reactivity with fibrinogen in an enzyme immunoassay (EIA). Y22 also reacts with fibrin of rabbits, rats, sheep, and dogs. The antibodies are of the IgG1 kappa-type and appear to be directed against a conformation-dependent epitope in the D-domain of fibrin. Experiments with 99mTc-labeled Y22 in vitro show that Y22 binds rapidly to forming clots. 99mTc-Y22 also binds to preformed plasma clots in a plasma milieu, even in the presence of high concentrations of heparin. Clot localization experiments in rabbits and rats confirm the high fibrin specificity and the potential of 99mTc-Y22 for thrombus imaging in vivo.

The effect of fresh versus stored blood on post-operative bleeding after coronary bypass surgery: a prospective randomized study

In a prospective study, 237 patients undergoing a primary coronary bypass operation were randomized to receive 2 units of fresh whole blood (study group) or stored (2-5 d) blood (control group) at the end of the extracorporeal circulation. Serious post-operative bleeding necessitating a re-thoracotomy occurred in 4.2% of all patients with an equal distribution over the two groups. Post-operative haemoglobin content and platelet counts were higher in the study group, but the differences were small and clinically not important. There were no differences in transfusion requirements, post-operative blood losses and haemostatic parameters between the trial groups. At low post-operative platelet counts (below 120 X 10(9) platelets/l) however, patients in the control group lost significantly more blood and had increased transfusion requirements compared with patients in the study group (7.1 versus 4.8 units). These differences must be attributed to qualitative platelet defects in the transfused units of stored blood. The small, clinically insignificant, differences in two laboratory parameters between the study and control groups, and the increased transfusion requirements of a subpopulation of patients with low platelet counts in the control group do not justify giving fresh blood or prophylactic platelet transfusions to coronary bypass patients.