Assessment of repeatability and treatment response in early phase clinical trials using DCE-MRI: comparison of parametric analysis using MR- and CT-derived arterial input functions

OBJECTIVES

Pharmacokinetic (PK) modelling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data requires a reliable measure of the arterial input function (AIF) to robustly characterise tumour vascular properties. This study compared repeatability and treatment-response effects of DCE-MRI-derived PK parameters using a population-averaged AIF and three patient-specific AIFs derived from pre-bolus MRI, DCE-MRI and dynamic contrast computed tomography (DC-CT) data.

METHODS

The four approaches were compared in 13 patients with abdominal metastases. Baseline repeatability [Bland-Altman statistics; coefficient of variation (CoV)], cohort percentage change and p value (paired t test) and number of patients with significant DCE-MRI parameter change post-treatment (limits of agreement) were assessed.

RESULTS

Individual AIFs were obtained for all 13 patients with pre-bolus MRI and DC-CT-derived AIFs, but only 10/13 patients had AIFs measurable from DCE-MRI data. The best CoV (7.5 %) of the transfer coefficient between blood plasma and extravascular extracellular space (K (trans)) was obtained using a population-averaged AIF. All four AIF methods detected significant treatment changes: the most significant was the DC-CT-derived AIF. The population-based AIF was similar to or better than the pre-bolus and DCE-MRI-derived AIFs.

CONCLUSIONS

A population-based AIF is the recommended approach for measuring cohort and individual effects since it has the best repeatability and none of the PK parameters derived using measured AIFs demonstrated an improvement in treatment sensitivity.

KEY POINTS

• Pharmacokinetic modelling of DCE-MRI data requires a reliable measure of AIF. • Individual MRI-DCE-derived AIFs cannot reliably be extracted from patients. • All four AIF methods detected significant K (trans) changes after treatment. • A population-based AIF can be recommended for measuring cohort treatment responses in trials.

Upper abdominal teratomas in infants: radiological findings and importance of the vascular anatomy

BACKGROUND

Primary upper abdominal teratomas are extremely rare tumours, most commonly arising in infants. The radiological literature relating to them is sparse. Surgical resection is difficult due to distortion of the vascular anatomy.

OBJECTIVE

To reassess the value of preoperative imaging with specific reference to the presence/absence of typical features of teratoma, anatomical location and adjacent vascular anatomy.

MATERIALS AND METHODS

The histopathology database was used to identify infants with upper abdominal teratoma. Pathological, surgical and radiological data were reviewed.

RESULTS

The search of the database identified 12 infants (10 girls, 2 boys) with an abdominal/retroperitoneal teratoma during the period 1993 to 2006. All teratomas were benign. In the majority of infants, typical radiological features of teratoma were demonstrated (fat, calcium). Identification of the major abdominal vessels on CT scan (most commonly the inferior vena cava) was not possible in all infants. Distortion (and commonly encasement) of the adjacent major abdominal vessels was usually evident.

CONCLUSION

Upper abdominal teratomas in infants have typical radiological features. Preoperative delineation of the major vascular anatomy is often imprecise. Significant distortion of vascular anatomy was present in all infants and awareness of this feature impacts on surgical planning.

Laparoscopic resection of extra-adrenal pheochromocytoma--case report and review of the literature in pediatric patients

Surgery for pheochromocytoma differs from that of other tumors owing to the potential release of catecholamines, which may lead to severe intraoperative hemodynamic changes. The present standard of care for resection of adrenal pheochromocytoma has become a laparoscopic approach for surgical excision. Extra-adrenal pheochromocytoma is a very rare entity, especially in the pediatric age group; the utility of the laparoscopic approach is not established in this population. We present a case report of a child with hormonally active extra-adrenal pheochromocytoma originating in the organ of Zuckerkandl that was resected laparoscopically. We found the laparoscopic approach gave excellent exposure, allowing for proper identification of the tumor's origin and its relation to surrounding structures; a complete resection with excellent control of the feeding blood vessels was performed. Herein we present the details of this case and a review of the relevant literature. After our initial experience we can recommend laparoscopic exploration for similar cases of suspected extra-adrenal pheochromocytoma as an appropriate tool to identify extension of the disease and estimate resectability. Proper patient preparation and monitoring are critical for success.

Contrast-Enhanced Abdominal Angiographic CT for Intra-abdominal Tumor Embolization: A New Tool for Vessel and Soft Tissue Visualization

C-Arm cone-beam computed tomography (CACT), is a relatively new technique that uses data acquired with a flat-panel detector C-arm angiography system during an interventional procedure to reconstruct CT-like images. The purpose of this Technical Note is to present the technique, feasibility, and added value of CACT in five patients who underwent abdominal transarterial chemoembolization procedures. Target organs for the chemoembolizations were kidney, liver, and pancreas and a liposarcoma infiltrating the duodenum. The time for patient positioning, C-arm and system preparation, CACT raw data acquisition, and data reconstruction for a single CACT study ranged from 6 to 12 min. The volume data set produced by the workstation was interactively reformatted using maximum intensity projections and multiplanar reconstructions. As part of an angiography system CACT provided essential information on vascular anatomy, therapy endpoints, and immediate follow-up during and immediately after the abdominal interventions without patient transfer. The quality of CACT images was sufficient to influence the course of treatment. This technology has the potential to expedite any interventional procedure that requires three-dimensional information and navigation.

Left Renal Vein Graft for Vascular Reconstruction in Abdominal Malignancy

BACKGROUND

Advanced abdominal malignancies are occasionally invasive for the major blood vessels, such as the portal vein (PV), inferior vena cava (IVC), and major hepatic veins (HVs), and complete removal of the tumors is required for patients undergoing vascular resection and reconstruction. We used left renal vein (LRV) grafts for vascular reconstruction in patients with these malignancies and evaluated their clinical relevance.

METHODS

A total of 113 patients underwent vascular resection including the PV (42 patients), IVC (68 patients), and HV (3 patients) for hepatobiliary-pancreatic or abdominal tumor resection. Of these, 11 patients underwent vascular reconstruction with a LRV graft of the PV, superior mesenteric vein (SMV), and HVs in 3 patients each, and the IVC in 2 patients. The HVs were resected with segmentectomy involving Couinaud's segments VII, VIII, and IV; VII, VIII, and II; or III, IV, VIII in each patient. The PV and SMV were resected in 5 patients undergoing pancreaticoduodenectomy for pancreatic carcinoma, and in 1 patient being treated with extended right hepatectomy and pancreaticoduodenectomy for hepatic hilar carcinoma. The IVC was partially resected in 1 patient with advanced colon cancer and 1 with malignant schwannoma.

RESULTS

The mean graft length of LRV obtained was 3.6 (3.5-4.0) cm. The graft was used as a tube in 9 patients, and as a patch in 2 patients. The mean duration of clamping time was 41.9 (35-60) min. Portal vein thrombosis was encountered in 2 patients, and anastomotic stenosis in 1 patient. Other morbidity was not related to vascular reconstruction. One patient who underwent extended right hepatectomy and pancreaticoduodenectomy died of liver failure in the hospital. The serum creatinine level after surgery did not deteriorate except in the one patient who died in the hospital. Graft patency was maintained during the follow-up period in all patients.

CONCLUSIONS

A LRV graft may enhance the possibility of vascular reconstruction without deteriorating serum creatinine level, and it provides sound graft patency.

Experimentally-derived functional form for a population-averaged high-temporal-resolution arterial input function for dynamic contrast-enhanced MRI

Rapid T(1)-weighted 3D spoiled gradient-echo (GRE) data sets were acquired in the abdomen of 23 cancer patients during a total of 113 separate visits to allow dynamic contrast-enhanced MRI (DCE-MRI) analysis of tumor microvasculature. The arterial input function (AIF) was measured in each patient at each visit using an automated AIF extraction method following a standardized bolus administration of gadodiamide. The AIFs for each patient were combined to obtain a mean AIF that is representative for any individual. The functional form of this general AIF may be useful for studies in which AIF measurements are not possible. Improvements in the reproducibility of DCE-MRI model parameters (K(trans), v(e), and v(p)) were observed when this new, high-temporal-resolution population AIF was used, indicating the potential for increased sensitivity to therapy-induced change.

Abdominal and pelvic stop-flow chemotherapy. Effect of chemotherapeutic agents and tissue ischemia on rectoanal pressures

In hypoxic stop-flow chemoperfusion high doses of chemotherapeutic agents are almost directly administered to locally advanced tumors without risking significant systemic toxicity, although chemotherapy-induced neurotoxicity is still a problem. The aim of the study was to assess rectoanal motility and sensation before, during and after abdominal and pelvic stop-flow chemotherapy using the methods of stationary and ambulatory manometry. Stationary rectoanal manometry was performed within 24 hrs before and repeated 48 hrs after stop-flow chemotherapy in 7 consecutive patients with a history of locally advanced or recurrent abdominal and pelvic tumors. Anal sphincter resting and squeeze pressures, rectal sensitivity, rectoanal inhibitory reflex and rectal volumes at which temporary and permanent urge to defecate were reported were examined. Rectal volume associated with leak of rectal contents and rectal compliance were also assessed. Intraoperatively, changes in rectal and anal resting pressures before, during and after occlusion of the vessels and after administration of chemotherapeutic agent were as well recorded, analyzed and interpreted using ambulatory manometry. Induction of anesthesia reduced distal and proximal anal resting pressures. Vascular occlusion further and dramatically decreased resting pressures at all levels, which were fully recovered after re-establishing local blood circulation and for the rest of the recording period. Intraoperative administration of chemotherapy did not further affect anal resting pressures during or after hypoxia. No significant changes in rectoanal motility and sensation were detected on the 48 hrs postoperative assessment as compared to the preoperative state. Tissue hypoxia induced by vascular occlusion during stop-flow chemotherapy procedure, seems to be the only factor leading to a dramatic drop of anal pressures. Anal pressures fully recover after reperfusion of the isolated area. Furthermore, anorectal motility and sensation are not affected by any direct or indirect toxic action of the chemotherapeutic agents.

Tumor endothelial marker 1 (Tem1) functions in the growth and progression of abdominal tumors

Tumor endothelial marker 1 (Tem1; endosialin) is the prototypical member of a family of genes expressed in the stroma of tumors. To assess the functional role of Tem1, we disrupted the Tem1 gene in mice by targeted homologous recombination. Tem1(-/-) mice were healthy, their wound healing was normal, and tumors grew normally when implanted in s.c. sites. However, there was a striking reduction in tumor growth, invasiveness, and metastasis after transplantation of tumors to abdominal sites in mice without functional Tem1 genes. These data indicate that the stroma can control tumor aggressiveness and that this control varies with anatomic site. Therefore, they have significant implications for the mechanisms underlying tumor invasiveness and for models that evaluate this process.

Tumor selective antivascular effects of the novel antimitotic compound ABT-751: an in vivo rat regional hemodynamic study

Selective induction of vascular damage within a growing tumor is a potentially important approach in the search for potent anticancer therapeutics. Tubulin-binding (antimitotic) agents destabilize cellular microtubules, suppress tumor growth, and exert antivascular effects with varying degrees of tumor selectivity in preclinical models. The tumor-selective, antivascular effects of ABT-751, a novel, orally active antimitotic agent, currently in phase II clinical development, were characterized in vivo in the present study. We developed an in vivo rat model designed to quantify acute changes in regional vascular resistance (VR) in both tumor and non-tumor vascular beds simultaneously. Tissue-isolated tumors (1 g) with blood flow supplied by a single epigastric artery were grown in rats. Subsequently, tumor blood flow was measured under anesthesia in solid tumors and also in mesenteric, renal, and normal epigastric arteries. Phenylephrine-induced (1 micromol/kg) increases in VR were not different between tumor and non-tumor epigastric arteries, suggesting that tumor vessels possess relatively normal vasoconstrictive function. ABT-751 (3, 10, and 30 mg/kg; i.v.) produced modest transient increases in mean arterial pressure with no effect on heart rate. Tumor VR increased to 75+/-36, 732+/-172, and 727+/-125% above baseline, respectively (P<0.05 for the 10 and 30 mg/kg doses), whereas VR in normal epigastric arteries was not significantly affected. Administration of ABT-751 produced transient modest ( P<0.05) increases in mesenteric VR and no effect on renal VR. These results demonstrate that ABT-751 produces marked reductions in tumor blood flow in the intact rat at doses that exert negligible effects on normal vascular function.

[Interdisciplinary operative procedure-pelvis and abdomen]

Surgery for tumors in the abdomen, retroperitoneum, and pelvis requires technical skills and expertise sometimes beyond the capability of a single surgeon. This holds especially true if curative tumor resection involves replacement of arteries and veins, which needs careful planning to avoid long periods of ischemia, and the selection and provision of vascular substitutes according to anatomical position, postsurgical therapy, and adjuncts to avoid thrombosis and infection of vascular grafts. Since the works of Fortner, the value of close collaboration between general and vascular surgeons has been demonstrated, but many of the former even today continue to attempt the operation alone, although the result is not always a masterpiece. The authors refer to their experience in major tumor surgery in either the single management of vascular complications or collaboration. The potential value of close collaboration is presented by negative examples, and a plea is made for a less "eminence"-based management of these sometimes difficult cases, which is based on vast positive experience with vascular diseases of the aorta and the visceral and iliac arteries and veins, including safety measures and adjuncts.

The laparoscopic approach to sacrococcygeal teratomas

BACKGROUND

Sacrococcygeal teratomas (SCT) are classically approached posteriorly through an inverted chevron incision. In large, external, mainly solid SCT, prior interruption of the arterial supply is warranted because of impending heart failure and life-threatening hemorrhagic diathesis. Hitherto, this has required prior laparotomy. A laparotomy is also added when the tumor extends presacrally into the pelvis. The presacral region is, however, difficult to access. A laparoscopic-assisted approach seems to offer a solution for both problems.

METHODS

A laparoscopic-assisted approach was used in five patients with SCT. In one neonate, it was used to interrupt the arterial blood supply only; in the other four patients, it was used to dissect the internal extension of the tumor.

RESULTS

Laparoscopic interruption of the median sacral artery proved to be simple in the neonate with a large, external, mainly solid SCT. In three of the remaining four patients with presacral extension of the tumor, good visualization and dissection of the intrapelvic portion of the tumor was obtained. In one patient, the procedure had to be converted because of a lack of working space due to extensive intraabdominal growth of the tumor.

CONCLUSION

A laparoscopic-assisted approach seems to be ideal for SCT. It provides the opportunity to interrupt the median sacral artery before the dissection. Moreover, it enables far better access to the presacral area than the conventional surgical approach when the SCT extends presacrally into the pelvis. Such a meticulous laparoscopic dissection may improve the functional results.

Continuous versus intermittent administration of human endostatin in xenografted human neuroblastoma

PURPOSE

The authors examined whether recombinant human endostatin (rhEndostatin), an antiangiogenic agent, is effective against a human neuroblastoma cell line (designated TNB9) using a human neuroblastoma xenograft model and investigated whether continuous infusion is more effective than intermittent administration.

METHODS

In the first experiment, when tumors on the back of nude mice reached a weight of 90 to 95 mg, rhEndostatin, 10 mg/kg/d mouse weight, was administered subcutaneously to the mice (n = 5) every day for 10 consecutive days. In the second experiment, the same daily dose of rhEndostatin was administered continuously to the TNB9-bearing mice (n = 6) via subcutaneous infusion pumps for 3 consecutive days with total dose being 30% of that in the first experiment. Nestin and factor VIII expression levels were studied immunohistochemically to elucidate whether histologic evidence of the effects of rhEndostatin was present on day 4 in the second experiment.

RESULTS

In the first experiment, relative tumor weight in treated mice (n = 5) was significantly less than that in controls (n = 12) on day 2 only after treatment initiation (P <.05). The maximum inhibition rate (MIR) of TNB9 xenograft growth by rhEndostatin was 46.4%, indicating lack of efficacy. In the second experiment, the effects of rhEndostatin were much more marked than those in the first experiment, with an MIR of 60.7%. The mean relative tumor weight in the treated group (n = 6) in the second experiment was significantly less than that in controls (n = 10) on days 2, 4, and 6 (P <.01) as well as on days 8 and 10 (P <.05). Nestin staining in the endothelium of control tumors (n = 2) was marked, whereas it showed a loss of fibrillar structure in rhEndostatin-treated tumors (n = 2). The number of vessels immunostained with antifactor VIII antibody was markedly reduced in tumors (n = 2) from rhEndostatin-treated mice compared with that in tumors from control animals (n = 2).

CONCLUSIONS

Continuous administration of rhEndostatin resulted in more significant tumor regression than intermittent administration of the agent in the same model. This indicates that rhEndostatin, if administered in continuous fashion, could become an effective agent for treating patients with neuroblastoma in the future.

Vascular endothelial growth factor and p53 expressions in liver and abdominal metastases from colon cancer

OBJECTIVE

To determine the relationship between p53 overexpression and vascular endothelial growth factor (VEGF) upregulation in liver and abdominal metastases from colon cancer. The analysis in the two metastatic sites was carried out to evaluate the potential role of microenvironment in the molecular regulation of VEGF.

METHODS

Bioptic specimens of liver and abdominal metastases from colon carcinomas were examined by immunohistochemistry for p53 and VEGF expressions. Consecutive cases with assessable tumor tissue were selected.

RESULTS

The study population consisted of 24 cases having liver metastases and 34 cases having abdominal metastases. Abdominal metastases showed a higher number of VEGF-positive cases and a higher intensity of VEGF immunoreactivity than liver metastases did (p = 0.01). The combined analysis of p53 and VEGF showed a strong association between the two markers in the 24 liver metastases; 9 cases were VEGF positive/p53 positive and 15 cases were VEGF negative/p53 negative. This relationship was not found in the 34 abdominal metastases, which showed concordance between the two markers in 9 VEGF-positive/p53-positive cases only.

CONCLUSIONS

Microenvironment factors like hypoxia may have a predominant role in inducing VEGF expression and they can override the molecular control of p53 on VEGF.

Very-high-flow injection rate for upper abdominal CT angiography

BACKGROUND

The purpose of this study was to compare a very-high-flow injection-rate method (group A) and a conventional injection-rate method (group B) for visualization of upper abdominal arteries by multidetector helical computed tomography (MDHCT).

METHODS

The subjects were 240 patients suspected to have abdominal lesions. They were randomly assigned to group A (120 patients) and group B (120 patients). In group A, the bilateral medial cubital veins were punctured, and contrast medium was infused at a rate of 8.6-9.6 ml/s. In group B, the unilateral medial cubital vein was punctured, and contrast medium was infused at a rate of 2.0-3.0 ml/s. The quality of vascular visualization was graded as poor, good, or excellent by three radiologists.

RESULTS

All visualizations of the celiac trunk (CE) and superior mesenteric artery (SMA) were graded as excellent in both group A and group B. Visualization grades of the subsegmental branches of the hepatic artery (HA), right gastric artery (RGA), cystic artery, dorsal pancreatic artery (DPA), and superior pancreaticoduodenal artery (SPDA) were good or excellent, in 75% (paging method)/53.3% (three-dimensional method), 85%/30%, 77.7%/18.3%, 76.7%/28.3%, and 88.3%/42.5%, respectively, in group A, and 33.3%/11.7%, 46.7%/3.4%, 41.6%/5%, 55%/4.2%, and 72.5%/14.2%, respectively, in group B. The appearance rate of intrahepatic portal branches was 28.3% in group A and 66.7% in group B in the arterial dominant phase.

CONCLUSION

Group A showed better visualization results than Group B in upper abdominal arteries according to MDHCT.

MR angiography: noninvasive vascular imaging of the abdomen

Magnetic resonance angiography (MRA) has been used to image abdominal vessels less frequently than renal arteries. Until the use of fast contrast-enhanced (CE) techniques, an important limitation was the acquisition time of phase-contrast or time-of-flight imaging and, consequently, the creation of motion artifacts. Recent advances in MRA technology have shortened acquisition times, so it is now possible to obtain successive images in the arterial and then the portal phase. MRA can be used as an adjunct to any MR examination to assess, e.g., the arterial feeding of hepatocellular carcinoma, the encasement of arteries, and segmental portal thrombosis in pancreatic carcinoma. However, MRA has been used mainly to study chronic mesenteric ischemia, portal vein diseases, and complications from liver transplantation. The portal venous system is exquisitely portrayed with this method; MRA is as accurate as digital subtraction angiography (DSA) in the diagnosis of portal vein diseases. Acute mesenteric ischemia is an emergency in which computed tomography is the most appropriate imaging modality. Conversely, chronic mesenteric ischemia is best examined with CE-MRA, which is almost as accurate as DSA. CE-MRA is superior to DSA for the simultaneous exploration of the aorta, renal arteries, and iliac arteries, thereby providing a panoramic view of abdominal vascular involvement. MRA can be coupled with measurements of flow. With this functional approach, MRA is the only modality that can completely assess vascular diseases of the abdomen.

[Multislice CT of the abdomen--current indications and future trends]

Multislice CT systems allow the simultaneous acquisition of multiple slices per gantry rotation. In combination with faster gantry rotation times of 0.5 seconds, the abdominal structures can be displayed in higher spatial and temporal resolution. In MS-CT of the liver it is possible to scan the entire organ with an optimal slice thickness of 2 - 3 mm within a defined perfusion phase in less than 10 seconds. This results in an improved detection and characterization of focal liver lesions. A high-quality, 3-dimensional reconstruction of the hepatic arterial and portalvenous system is obtained with the same data set. The diagnostic use of the simultaneously acquired perfusion data will lead to a better characterization of focal liver lesions in the future. The diagnostics of the pancreas also profits from MS-CT, especially for the detection of small tumors and the evaluation of resectability of a pancreatic carcinoma. All abdominal structures can be displayed in a coronal view without loss of image quality because of the almost isotropic voxels obtained. This proves to be beneficial for the preoperative diagnostics of renal cell carcinomas, especially if the tumor extension into adjacent organs (e. g., liver or spleen) in the longitudinal direction has to be evaluated. The multiplanar display and the sophisticated 3-dimensional reconstruction tools have a substantial value for the abdominal CT angiography. It proves to have a major diagnostic impact on acute abdominal aortic and visceral arterial diseases because even large distances in the z-direction can be covered with high spatial resolution.

Treatment of unresectable malignant abdominal, pelvic and thoracic tumors using abdominal pelvic and thoracic stop-flow chemotherapy

BACKGROUND

Stop-flow perfusion (SFP) has been recently used to enhance the effects of chemotherapy in patients with locally advanced tumors.

PATIENTS AND METHODS

Over a 2-year period we performed abdominal, pelvic and thoracic SFP in 12 patients with unresectable or metastatic tumors, using balloon catheters inserted into the abdominal aorta and inferior vena cava. Blood flow was occluded and hypoxic extracorporeal perfusion or SFP was performed for advanced diseases. The chemotherapeutic agents were directly administered into the aorta and/or inferior vena cava for thoracic SFP. The procedure was repeated in each patient, with one-month interval between sessions. Haemofiltration was also applied in two patients with generalized abdominal disease in order to reduce systemic toxicity.

RESULTS

At post-operative CT or MRI follow-up, tumor shrinkage of more than 50% was observed in six patients, while post-SFP chemotherapy surgical resection of the tumors became feasible in four cases. The relief of pain, wherever present, was dramatic in the immediate post-operative period. Overall clinical improvement was achieved in all 12 patients. Post-operative recovery was uneventful in all but two patients, who developed minor systemic toxicity.

CONCLUSION

SFP appears to be a safe technique with low morbidity which improves the quality of life of cancer patients and allows satisfactory control of locally advanced tumors and metastatic carcinomatosis.

Three-dimensional gadolinium-enhanced MR angiography: applications for abdominal imaging

Three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography is a versatile technique that combines speed, superb contrast, and relative simplicity. It has a wide range of applications, particularly in the abdomen and pelvis, where superb images of the abdominal aorta and renal arteries are routinely obtained. Aneurysms, atherosclerotic lesions, and occlusions of the major mesenteric arteries are also well depicted. In addition, 3D gadolinium-enhanced MR angiography is ideal for noninvasive evaluation of the systemic and mesenteric veins and can be used to demonstrate parenchymal lesions in the liver, pancreas, kidneys, and other organs. It is also useful in staging genitourinary neoplasms: Parenchymal lesions, venous extension, and adenopathy are all clearly depicted. Three-dimensional gadolinium-enhanced MR angiography can be useful in the preoperative evaluation of potential transplant donors and recipients and in the evaluation of vascular complications following transplantation. Delayed 3D acquisitions of the kidneys, ureters, and bladder can be performed routinely to generate gadolinium-enhanced urograms and demonstrate obstruction, delayed function, filling defects, and masses. A variety of methods for increasing the speed and improving the resolution of 3D acquisition are currently under investigation. These include novel imaging and reformatting techniques and the use of intravascular contrast agents with much longer vascular half-lives.

Clinical report: contrast enhancement of tumor perfusion as a guidance for biopsy

We describe three cases where biopsies from various tumors were guided by contrast enhancement of tumor perfusion. After i.v. administration of Levovist (Schering AG, Berlin, Germany), the tumors showed both hyper- and hypovascular areas. Biopsies from the latter showed marked necrosis or fibrosis. This may cause biopsies not being conclusive. To ensure fully diagnostic biopsies from irregular tumors we propose the biopsy to be performed from the most vascular part demonstrated by contrast enhancement.

Abdominal involvement in neurofibromatosis 1: sonographic findings

BACKGROUND

Neurofibromatosis 1 (NF1) has been studied from many viewpoints, but its abdominal involvement has rarely been reported. Sonography (US) is now the initial diagnostic tool for abdominal exploration, which prompted us to determine the clinical manifestations and US findings of abdominal involvement in NF1.

METHODS

We analyzed the US findings and clinical data of eight NF1 cases with abdominal involvement.

RESULTS

Abdominal involvement included neurofibromatous tumor growth in the liver, mesentery, and retroperitoneum, in addition to mesenteric leiomyomatosis and gastric carcinoma. Color Doppler US was useful not only in detecting blood flows in the lesions but also in preventing hazardous vascular injury during tumor biopsy.

CONCLUSION

A better understanding of the clinical manifestations and US findings of abdominal involvement in NF1 translates into improved NF1 patient care.

Abdominal MR imaging with a volumetric interpolated breath-hold examination

PURPOSE

To compare a T1-weighted, three-dimensional (3D), gradient-echo (GRE) sequence for magnetic resonance (MR) imaging of the body (volumetric interpolated breath-hold examination, or VIBE) with a two-dimensional (2D) GRE breath-hold equivalent.

MATERIALS AND METHODS

Twenty consecutive patients underwent 1.5-T MR imaging. The examinations included pre- and postcontrast (20 mL gadopentetate dimeglumine) fat-saturated 2D GRE breath-hold imaging and fat-saturated volumetric interpolated breath-hold imaging before, during (arterial phase), and after injection, with thin (2-mm source images) and thick (8-mm reconstruction images) sections. The three images were compared qualitatively and quantitatively (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]).

RESULTS

Qualitatively, the 2-mm source images had poorer pancreatic edge definition on precontrast images compared with the other two data sets (P < .05). On gadolinium-enhanced images, scores for clarity of pancreatic edge, number of vessels visualized, and arterial ghosting were significantly lower for the postcontrast 2D GRE images. Quantitatively, SNR measurements in the liver, aorta, and renal cortex on pre- and postcontrast images were significantly higher for the 8-mm reconstruction images than for the 2D GRE or 2-mm source images (P < .05). Aorta-to-fat CNR was significantly higher on the 8-mm reconstruction images.

CONCLUSION

Fat-saturated volumetric interpolated breath-hold images have quality comparable to that of conventional fat-saturated 2D GRE images.

[Vascular surgery within the scope of visceral surgery-oncologic interventions]

The surgeon dealing with oncological operations within the abdominal cavity will be frequently confronted with vascular problems. These include surgically relevant vascular anomalies, arteriosclerotic changes, tumor infiltration of vessels and iatrogenic vascular lesions. The diagnosis, indications and, above all, the vascular surgical techniques applied during oncological procedures on the pancreas and liver are described in this review.

Vascular complications of total abdominal perfusion and aortic stop-flow infusion

During a 2 year period (1992-1993), 149 patients with advanced abdominal cancer underwent total abdominal ischemic perfusion (TAP) and stop-flow infusion (SFI) 159 times in an attempt to achieve palliation. These procedures and aortic stop-flow infusion require insertion of balloon catheters into the abdominal aorta and inferior vena cava by a transfemoral approach. Flow is arrested for 15 minutes, during which time chemotherapeutic agents are infused into the aorta, distal to the balloon occlusion. Femoral access is by a surgical incision. The passage of the catheters is guided by fluoroscopy. Some tumor response was observed in 35% of the patients. Ten patients had major vascular complications; two iliac artery aneurysms were lacerated and required emergency repair. There were two femoral artery false aneurysms that required surgical correction, one early and one late. Aortic dissection was detected in four patients, but these did not require surgical intervention. Two patients had thrombosis distal to the occluded vessel, both required surgical intervention. To reduce the incidence of these vascular complications we recommend: (1) a clinical and vascular laboratory evaluation before the procedure, and (2) angiography of normal flow in patients with underlying vascular disease.

[Three-dimensional helical CT angiography of the abdomen]

To evaluate the quality of three-dimensional (3D) images of the abdominal vasculature acquired using enhanced helical CT, 3D reconstructions were performed for 43 examinations (38 patients). Twenty-one of 43 examinations were also reconstructed by Maximum Intensity Projection (MIP). The CT scanner employed was the Toshiba Xforce. Helical CT data were acquired using up to 20 continuous 1.5-sec rotations with an X-ray beam width of 5 mm and a couchtop movement speed of 5 to 10 mm/1.5 sec. Axial images were reconstructed at a section interval of 2 mm. Optimal protocol on enhanced helical CT was as follows: Iopamidol 300 mg I/ml was administered intravenously using a biphasic technique (3-4 ml/sec for the initial 100 ml, followed by 0.7-1.5 ml for the remaining 50 ml), and delay times of the early and late phases were 25-35 and 90 sec, respectively. Aortic branches were clearly demonstrated on early phase, while portal branches were well defined on late phase. In the visualization of abdominal vessels, 3D images were nearly equal to MIP images. However, for anteroposterior images, MIP images were superior to 3D images in quality, because 3D images had some longitudinal direction artifacts. Three-dimensional images were considered to be useful for correctly evaluating overlapping abdominal vasculatures. From the above results, 3D and MIP images of the abdominal vasculature obtained using enhanced helical CT were considered to compensate for each other.

Radical surgery for abdominal neuroblastoma

Radical operation predominantly for those with stages III and IV, i.e., locally advanced and/or metastatic abdominal neuroblastoma, is described. Generally the surgery has been performed when tumour shrinkage has been achieved by means of chemotherapy, and metastases have been ablated. The author compares his results in 46 patients with those of 34 patients undergoing less aggressive surgery performed by a number of surgeons, with similar results. Given the difficulties inherent in performing curative resection for disseminated abdominal neuroblastoma, the surgeon needs to be convinced that his/her efforts are worthwhile. The results reported here do not provide such reassurance.

Venous surgery in resection for abdominal malignancy

Vascular surgical techniques were applied to the radical resection of carcinoma of the liver, biliary tract and pancreas. Distal and proximal portal vein reconstruction, respectively, was carried out in 16 patients with carcinoma of the pancreas and 16 with cancer of the liver and biliary tract. Hepatic vein trunks with tumour involvement were resected and reconstructed by various techniques in six patients. A suprarenal segment of the inferior vena cava was completely replaced by a prosthetic graft in three patients with retroperitoneal malignancy. Venous surgery increased the resectability of malignant tumours and preserved circulation in the organ remnant, although the long-term effect on survival is not yet clear. Vascular surgical techniques should be applied more widely in the field of general abdominal surgery.

[Magnetic resonance angiography in the study of abdominal neoplasms. Preliminary experience]

This study was designed to evaluate MRA imaging as a potential non-invasive method to study vascular infiltration in patients with abdominal neoplasms. Forty-three patients with abdominal tumors proven by CT and/or MRI were examined with MRA and subsequently with angiography. Of 15 cases of liver tumor, MRA allowed poor intratumoral vascularization to be demonstrated in 1 patient only, but it always provided a characteristic sign--i.e., the complete absence of flow in the hepatic segments infiltrated by the tumor and the evidence of pericapsular neovascularization. In 8 cases portal vein involvement was observed (4 cases of compression/dislocation, 2 cases of infiltration and 2 of thrombosis). In all cases MRA allowed the relationship between tumor and venous structures to be evaluated. It also demonstrated collateral vessel formations in 8 patients with cancrocirrhosis. Two cases of thrombosis and 3 infiltrations of the vena cava were demonstrated. Neither hepatic artery nor intrahepatic arterial vascularization could be correctly evaluated. Of 10 cases of renal tumors and in 3 of adrenal tumors, renal vein infiltration was seen in 4 cases and compression in 3, with only 1 false-positive finding. In these patients and in those with retroperitoneal masses, MRA provided valuable information on the relationship between tumor and vascular structures and was useful in detecting collateral vessels. In our experience, MRA is to be considered as a complementary technique to be performed after CT or MRI when additional information is needed as to the relationship between tumor and vascular structures. In the preoperative evaluation of abdominal neoplasm, angiography remains the gold standard, in spite of its invasiveness.

[MR tomography and MR angiography--a new method for the planning of the irradiation of large abdominal fields]

Subdiaphragmatic radiation therapy in malignant lymphoma requires complete irradiation of retroperitoneal lymph nodes, spleen and splenic pedicle and optimal shielding of radiosensitive structures. The aim of our study was to develop a new method for individual field definition by using MR tomography and MR angiography. In 38 patients with malignant lymphoma coronal MR tomograms and MR angiograms of the abdominal vessels were obtained and superimposed by a specially created computer program. By using a Subtraskop the MRT/MRA superposition was geometrically projected onto the simulation film in correct scale. The target volume could individually be defined and was compared to standard treatment planning according to the definition by Abbatucci. In all patients an exact irradiation of the spleen, the splenic pedicle and prominent lymphatic masses was possible. Furthermore, this resulted in a 32% reduction of treated kidney volume in the average of patients. Noninvasiveness, acceptable costs and high accuracy support the application of this new method in clinical routine.

Blood flow and steady state temperatures in deep-seated tumors and normal tissues

Blood flow related data obtained in different deep-seated tumors and adjacent normal tissues were analyzed in 28 patients who were treated with combined regional hyperthermia and radiation for recurrent or metastatic tumors. The evaluation of blood flow related data has been made using the thermal clearance/thermal cooling coefficient technique and dynamic computed tomography. With both methods significant differences in global perfusion have been observed between tumor center and tumor periphery, between tumor and normal tissue (deep muscle and fat tissue), and between tumor entities. Washout rates or thermal cooling coefficient values, as well as the enhancement of contrast material over baseline (expressed in delta Hounsfield Units), correlated significantly with the achieved steady state temperatures for different tissue categories (i.e., tumor center, tumor periphery, different tumor entities, normal tissue). Thermal cooling coefficient values higher than 63000-83000 W/m3-K (washout rates higher than 15-20 ml/100 g-min) or values of enhancement of contrast material higher than delta 20-25 HU coincide with a limitation in achieving therapeutic temperatures higher than 40 degrees C.

Clinical investigations on blood perfusion in human malignancies of the pelvis and abdomen: significance for tumor therapy

Blood flow of deep pelvic and abdominal tumors was investigated with the thermal clearance method, dynamic CT and dynamic MRI. There are good correlations between the measurement values obtained by these methods. A low flow was observed in rectal cancer and soft tissue sarcoma in contrast to pancreatic cancer and hypernephroma. The temperature increase induced by regional hyperthermia was dependent on the individual tumor blood flow. Dynamic CT can be used pretherapeutically and predict the quality of a heat treatment, which is important with regard to concepts consisting in radiotherapy or chemotherapy plus hyperthermia.

[Visualization of blood flow in abdominal tumors by the ultrasonic pulsed Doppler method]

The clinical utility of visualizing the blood flow in the margin and inside of tumors by ultrasonic pulsed Doppler method (UPDM) was evaluated in 54 patients (85 lesions) with various abdominal tumors. It was proved that UPDM was able to evaluate the vascularity of the tumor and the surrounding vascular system. These results indicate that this method may be applied clinically for judging the effects of and the indications for the transcatheter arterial embolization (TAE) therapy. It is also suggested that UPDM may be applied in the differential diagnosis of tumors according to the changes of blood velocity and wave patterns.

Angiography of omental mesothelioma

Angiographic features of three cases of omental mesothelioma are presented. These lesions appeared mildly or moderately hypervascular without arteriovenous shunting or arterial encasement. The predominant feeding arteries were the right and left gastroepiploics. Since arteriography may be performed in the evaluation of the often nonspecific presenting symptoms of patients with abdominal mesothelioma, radiologists should be aware of these abnormalities.

Intravenous contrast bolus in computed tomography investigation of mass lesion

Using bolus intravenous contrast (25-75 Renografin 60) and 5-second scanning capability, better definition of vascular anatomy as well as the vascular nature of mass lesions in the chest and abdomen could be demonstrated. The immediate higher concentration of iodine in vessels and organs following initial bolus, improves visualization of these structures dramatically when compared to drip-infusion technique. A description of the technique and examples are shown.

Uniform regional heating of the lower trunk: numerical evaluation of tumor temperature distributions

The temperature distributions in deep seated tumors resulting from uniform heating of the abdominal and pelvic regions of the trunk are predicted from a one dimensional numerical solution of the bio-heat transfer equation. The effect of tumor size and location are investigated for two tumor perfusion models: uniform perfusion and a concentric annulus perfusion model. Tumor temperature distributions are considered acceptable if the range of temperatures in the tumor lie between 42 degrees C and 60 degrees C. This range of tumor temperatures is defined as Tave +/- 2 sigma where sigma is the population standard deviation of tumor temperatures from the average computed at the nodal points in the finite difference array. To simulate practical clinical restrictions, muscle and fat temperatures are not allowed to exceed 44 degrees C, significant portions of the viscera are not allowed to exceed 42 degrees C, and the total absorbed power required to maintain steady state cannot exceed two kilowatts. Over 100 possible cases are presented in a compact form. From this study it appears that heating systems with power deposition patterns approximately uniform are promising for heating deep-seated tumors. Small, detectable tumors (approximately 2 cm in size) are adequately heated for a wider range of conditions than are larger tumors. Excessively high temperatures in deep-seated, normal tissue could be a significant limitation for this technique.

Blood flow in human tumors during hyperthermia therapy: demonstration of vasoregulation and an applicable physiological model

A quantitative assessment of the effect of localized magnetic-loop hyperthermia on blood flow was performed in 12 human tumors using the 133Xe clearance method. Because blood flow in these tumors changed in response to needle injection, a physiologically based, one-compartment model was developed that included both a hyperemic and a steady-state component. In six tumors, changes in blood flow induced by heat were also observed. The ability of tumor vessels to respond dynamically to stress and the degree of response may be predictive of tumor heating capacity and subsequent therapeutic response.

The parasitic blood supply of abdominal masses

Many lesions, and particularly hyper-vascularized ones, acquire an aberrant blood supply. These parasitic vascular supplies are defined as tumour vascularizations derived from neighbouring organs or structures, and supplement the normal blood supply of the diseased organ. Their existence is essential for the angiography of abdominal masses. We selected 35 cases of abdominal masses with parasitic vascular networks. Twenty-four belonged to an initial review of 117 angiographic studies of abdominal masses. Eleven have been added in accordance with the theme of this work. Parasitic circulations should be taken into account because of their effects on the angiographic technique, their diagnostic possibilities and limitations, and their importance in the management of the patient.

The results of angiographic studies of abdominal masses

This study reveals the continuing great viability of angiography in the investigation of abdominal masses. It is a fundamentally important procedure within the context of presurgical evaluation. Certain points should be underlined. - The radiological definition of the histological nature of an abdominal mass during angiography remains difficult, practically impossible in certain regions. - Borrowed vascularizations still pose complex diagnostic problems at different levels. - The benefit of angiography should be compared with other modern radiodiagnostic methods, especially the less aggressive ones. - The importance of each of these points has led us to develop them separately: - The diagnostic reliability of angiography in abdominal masses (from anatomico-radiological correlations). To be published - The borrowed vascularisation of abdominal masses. To be published - The tomodensitometry of abdominal masses. To be published - Diagnostic strategy in case of an abdominal mass. To be published.

[Diagnosis of an upper abdominal tumor by computed tomography(auauthor's transl]

In this case of a pulsating upper abdominal tumor an angiographic examination was indicated even though an aortic aneurysm had been excluded and the affected organ identified by means of sonography and computed tomography.

Lymphography in childhood rhabdomyosarcomas

Forty-one children with subdiaphragmatic rhabdomyosarcoma underwent bipedal lymphography. Twenty-two (53.5%) of the lymphograms were interpreted as being positive. In our series, the lower limbs were the most common primary site of involvement, were more frequently involved by the alveolar histologic subtype which carries a poor prognosis, and were associated with a higher incidence of lymph node metastases. Positive lymphographic findings in this group of children were similar to those seen in both adults and children with other solid tumors, i.e., the presence of discrete lymph node filling defects. However, in 3 cases, abnormalities more characteristic of lymphoma were identified. Evaluation of lymph node metastases as demonstrated by lymphography has prognostic significance.

[Angiography in abdominal diseases (author's transl)]

Angiography of arteries and veins in the abdominal and retroperitoneal compartement is a valuable routine roentgenologic procedure. Its value in the diagnosis of vascular disorders is apparent. Regarding space occupying lesions in the abdomen angiography is an aid in diagnosis and differential diagnosis and provides information on the curability. Visualization of the venous system will give mainly information on the extent of a tumor. For an evaluation of portal hypertension the arterial indirect visualization of the portal venous system is superior to the direct percutaneous splenoportography. In the acute gastrointestinal bleeding selective angiography is able to demonstrate the bleeding site.

Transcatheter brush biopsy of intravenous tumor thrombi

Transcatheter brush biopsy of intraluminal filling defects demonstrated during venography was performed in 6 patients with abdominal neoplasms. Tissue specimens consistent with either known or subsequently proved tumor were obtained from 4 patients. Biopsy was negative in the other 2 patients, who lacked surgical confirmation of the intraluminal mass. This technique is useful in establishing histological proof of neoplasm and in determining the extent of known tumor.

Transcatheter occlusion of abdominal tumors

Radiological and clinical experience with transcatheter intravascular occlusion of abdominal and pelvic tumors in 55 patients is presented. Major indications include control of hemorrhage, palliation of local tumor symptoms, and preoperative management of facilitate surgery. Methods of occlusion included embolization (clot, subcutaneous tissue, and Gelfoam), introduction of a stainless steel coil into larger vessels, and balloon catheters. Hemorrhage was controlled in 8 of 12 patients with bleeding gastrointestinal and pelvic tumors. Experience in 36 patients with hypernephroma is discussed. Initial observations are presented, including occlusion of the hepatic artery for dearterialization of primary and secondary neoplasms and of the splenic artery for hypersplenism.