News in magnetic resonance imaging use for radiation oncology

The purpose of this article is to give a summary of the progress of magnetic resonance imaging (MRI) in radiotherapy. MRI is an important imaging modality for treatment planning in radiotherapy. However, the registration step with the simulation scanner can be a source of errors, motivating the implementation of all-MRI simulation methods and new accelerators coupled with on-board MRI. First, practical MRI imaging for radiotherapy is detailed, but also the importance of a coherent imaging workflow incorporating all imaging modalities. Second, future evolutions and research domains such as quantitative imaging biomarkers, MRI-only pseudo computed tomography and radiomics are discussed. Finally, the application of MRI during radiotherapy treatment is reviewed: the use of MR-linear accelerators. MRI is increasingly integrated into radiotherapy. Advances in diagnostic imaging can thus benefit radiotherapy, but specific radiotherapy constraints lead to additional challenges and require close collaboration between radiologists, radiation oncologists, technologists and physicists. The integration of quantitative imaging biomarkers in the radiotherapy process will result in mutual benefit for diagnostic imaging and radiotherapy. MRI-guided radiotherapy has already been used for several years in clinical routine. Abdominopelvic neoplasias (pancreas, liver, prostate) are the preferred locations for treatment because of their favourable contrast in MRI, their movement during irradiation and their proximity to organs at risk of radiation exposure, making the tracking and daily adaptation of the plan essential. MRI has emerged as an increasingly necessary imaging modality for radiotherapy planning. Inclusion of patients in clinical trials evaluating new MRI-guided radiotherapy techniques and associated quantitative imaging biomarkers will be necessary to assess the benefits.

Selective microsurgical treatment of giant intracranial aneurysms

Giant intracranial aneurysms are defined as greater than 25mm in diameter. They share the same surgical challenges and strategies as so-called complex aneurysms, sometimes smaller in size but presenting with similar complex anatomy. The surgical difficulties arise from the size of the sack, the presence of intraluminal thrombus, the thickness of the arterial wall, and the complexity of arterial branching on the neck. Preoperative imaging gathers complementary information from magnetic resonance imaging, computed tomographic angiography, and rotational catheter-based angiography with three-dimensional reconstruction including balloon-test occlusion. The therapeutic decision-making needs a multidisciplinary approach including endovascular, neurosurgical and anesthesiological expertises. The microsurgical treatment needs a step-by-step preoperative planning with anticipation of possible pitfalls and alternative strategies. Classical principles of aneurysm surgery have to be tailored to face the difficulties arising from the size of the sack and from the arterial wall calcifications.

[Blood cardioplegia: advantages and disadvantages]

Blood cardioplegia is worldwilde used during cardiac surgery. It provides a safe myocardial protection during this surgery. All along the year blood cardioplegia has been improved but it's of importance to apply it correctly. This can be a disadvantage during some cardiac surgery technics.

Non-invasive prediction of fluid responsiveness during major hepatic surgery

BACKGROUND

The aim of this study was to evaluate potential predictors of fluid responsiveness obtained during major hepatic surgery. The predictors studied were invasive monitoring of intravascular pressures (radial and pulmonary artery catheter), including direct measurement of respiratory variation in arterial pulse pressure (PPVart), transoesophageal echocardiography (TOE), and non-invasive estimates of PPVart from the infrared photoplethysmography waveform from the Finapres (PPVfina) and the pulse oximetry waveform (PPVsat).

METHODS

We conducted a prospective study of 54 fluid challenges (250 ml colloid) given for haemodynamic instability in eight patients undergoing hepatic resection. Fluid responsiveness was defined as an increase in stroke volume index (SVI) >or=10%. The following variables were recorded before each fluid challenge: right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), PPVart, PPVfina, PPVsat, and the TOE-derived variables left ventricular end-diastolic area index (LVEDAI), early/late (E/A) diastolic filling wave ratio, deceleration time of the E wave (MDT) of mitral flow and the systolic fraction of the pulmonary venous flow (SF).

RESULTS

Only PPVfina, PPVart (both P<0.001), PPVsat (P=0.02), LVEDAI and MDT (both P=0.04) were different in responder vs non-responder fluid challenges. The areas under the receiver operating characteristic (ROC) curves were 0.81 (PPVfina), 0.79 (PPVart), 0.70 (LVEDAI), 0.68 (PPVsat and MDT), 0.63 (RAP), 0.62 (E/A), 0.55 (PAOP) and 0.42 (SF). The areas under the ROC curves for RAP, E/A, PAOP and SF were significantly less than that for PPVfina (P<0.05 in each case). Only PPVart (r=0.59, P=0.0001) and PPVfina (r=0.56, P=0.0001) correlated with the fluid challenge-induced changes in SVI.

CONCLUSIONS

PPVart and PPVfina predict fluid responsiveness during major hepatic surgery. This suggests that intraoperative monitoring of fluid responsiveness may be implemented simply and non-invasively.

Thrombose tardive d'une endoprothèse coronaire pharmacoactive après arrêt des agents antiplaquettaires

We reported the late thrombosis of a drug-eluting coronary stent related to discontinuation of antiplatelet therapy for venous surgery of the right leg more than half and a year after its implantation. After this acute myocardial infarction, a cardiac assistance device has to be used as a bridge to transplantation because of end stage ischaemic cardiopathy. Antiplatelet therapy management must be revisited for eluting stents, which can clot lately after its implantation.

Stent-graft repair of the thoracic aorta: short-term results

The purpose of this study was to evaluate clinical feasibility and immediate outcome of stent-graft repair of the thoracic aorta. From December 1999 to January 2001, a total of 14 patients underwent stent-graft repair of the thoracic aorta. The underlying etiologies were traumatic rupture of the aortic isthmus in four cases, Stanford type B dissection in four, thoracic aortic aneurysm in three, penetrating atherosclerotic ulcer in two cases, and postoperative aortoesophageal fistula in one case. Stent-graft placement was performed under angiographic control in all cases in association with transesophageal echography in seven cases. The procedure was performed under emergency conditions in five cases. Thirteen patients presented contraindications for surgery. Stent-graft placement was successful in all cases. No further surgery has been performed in any case. Thus we conclude that endovascular treatment of the thoracic aorta using stent grafts is a promising therapeutic modality in patients with contraindications for conventional surgical treatment.

Ross operation for active culture-positive aortic valve endocarditis with extensive paravalvular involvement

BACKGROUND

We evaluated the midterm results of the Ross operation in active advanced endocarditis.

METHODS

Between June 1994 and June 2000 a pulmonary autograft aortic root replacement was performed in 11 consecutive patients who had urgent or emergent procedures for active endocarditis with extensive involvement of the aortic root (10 native, 1 prosthetic). Patients ranged in age from 26 to 45 years (median, 33 years). Indications for operation were uncontrolled infection (n = 5), hemodynamic deterioration (n = 3), or both (n = 3). Four patients were in the New York Heart Association class III, 6 in class IV, and 1 was operated on while in cardiogenic shock. Four patients (36%) suffered an embolic cerebrovascular accident preoperatively. The endocarditis affected the mitral valve in 2 patients and the tricuspid valve in 1 patient.

RESULTS

There was no early or late death. Recurrent endocarditis was not detected in any of the patients during the follow-up period ranging up to 72 months (median, 40 months).

CONCLUSIONS

The autograft may well be the best substitute for aortic root reconstruction in advanced endocarditis.

Pilot study with air-automated sigmoid capnometry in abdominal aortic aneurysm surgery

BACKGROUND

and objective Ischaemic colitis can be a serious complication after aortic surgery. The paucity of clinical symptoms makes its diagnosis particularly difficult and often delayed. Automated on-line tonometry is now proposed to monitor intestinal perfusion. This study was designed to assess the use of semi-continuous sigmoid-to-arterial [P(r-a)CO(2)] PCO(2) gap monitoring in aortic surgery to detect colonic ischaemia.

METHODS

This prospective clinical study was realized at the University Hospital of Lille, France, including eight males scheduled for abdominal aortic aneurysm surgery. Intraoperative and postoperative P(r-a)CO(2) values were compared with conventional monitoring and colonic mucosa aspect performed by sigmoidoscopy 48 h after surgery. Haemodynamic variables, O(2) delivery (DO(2)), O(2) consumption (VO(2)), O(2) extraction (ERO(2)), lactate, P(v-a)CO(2), P(r-a)CO(2) were measured peroperatively and every 4 h during a 48-h postoperative period.

RESULTS

Intraoperative P(r-a)CO(2) values increased significantly with the highest value (4.36 +/- 3.42 kPa) observed during aortic clamping when DO(2) was the most altered. P(r-a)CO(2) continued to deteriorate after surgery with the maximal values between 8 (4.79 +/- 3.85 kPa) and 12 (4.68 +/- 3.26 kPa) h after surgery. This peak was associated with a significant ERO(2) increase counterbalancing an increase of VO(2) whereas DO2 tended to decrease. P(r-a)CO(2) values began to decrease only at the end of the study. The highest values of P(r-a)CO(2) were registered in patients with the most altered haemodynamic variables, severe ischaemic colitis along with higher hospital lengths of stay.

CONCLUSION

Taken together, these data suggest that regional and automated capnometry may be easily used non-invasively to detect peroperative intestinal ischaemia in aortic surgery.

[Hemodynamic instability and paraplegia after thoracotomy for excision of a cardiac pheochromocytoma]

We report the occurrence of a sustained hypotension (vasoplegia) following thoracic phaeochromocytoma surgery. Diagnosis of spinal cord injury was done by magnetic nuclear resonance (MNR) showing surgical "Horsley wax" inside the vertebral canal and ischaemic signal inside the anterior part of the spine cord. Removal of "Horsley wax" dramatically improved arterial blood pressure but did not correct all neurologic disorders. Haemodynamic disorders related to spinal cord injury are rare after thoracotomy, and may have been enhanced by the haemodynamic instability typically associated with phaeochromocytoma surgery. Early diagnosis has to be done by MNR.

Use of inhaled nitric oxide for emergency Cesarean section in a woman with unexpected primary pulmonary hypertension

PURPOSE

Use of inhaled nitric oxide (iNO) could be of importance in emergency cases of primary pulmonary hypertension (PPH) in pregnant patients during labour and delivery. iNO acts as a selective pulmonary bed vasodilator avoiding systemic hemodynamic effects due to its ease of administration. Pulmonary bed vasodilation improves right ventricular function directly and left ventricular function indirectly.

CLINICAL FEATURES

We report the case of a pregnant patient with unexpected PPH in whom an emergency Cesarean section (CS) had to be performed. PPH was diagnosed on admission as she arrived in active labour at 34 weeks gestational age. An emergency CS was performed under epidural anesthesia for breech presentation . All along labour, delivery and the first 24 hr, iNO was administered via a noninvasive ventilation device. CS was uneventful. A severe pulmonary hypertensive crisis was observed 12 hr after delivery and resolved with an increase of iNO concentration and administration of isoprenalin. The patient and baby returned home on day ten.

CONCLUSION

The ease of administration of iNO allowed the optimal control of pulmonary arterial hypertension. No interaction with epidural anesthesia was observed. Use of iNO can improve the management of urgent CS in women with unexpected PPH.

Total orthotopic heart transplantation for primary cardiac rhabdomyosarcoma: factors influencing long-term survival

BACKGROUND

Primary cardiac sarcomas are uncommon and rare, with an unequal distribution in the population. A dismal prognosis is usually admitted that is related to a high propensity to develop distant metastasis with survival rarely exceeding 2 years. We report a case of a patient with a primary cardiac rhabdomyosarcoma characterized by an exceptional long-term survival after surgical treatment by a total orthotopic heart transplantation. From this limited experience, we reviewed factors that may influence survival to optimize therapeutic strategy.

METHODS

A 33-year-old man was found to have a 10-cm primary cardiac rhabdomyosarcoma located in the right atrium and extending to the atrioventricular groove; therefore, resection was not possible. Since no metastases were detected, the patient was scheduled for urgent cardiac transplantation, which was performed after adjuvant radiotherapy.

RESULTS

Postoperative outcome was uneventful and the patient is still alive, with regular follow-up, at 102 months.

CONCLUSIONS

In a case of primary rhabdomyosarcoma, heart transplantation, despite immunosuppressive therapy, can provide long-term survival and can be considered for selected patients after rigorous analysis of predictors of survival.

Cardiac valve papillary fibroelastomas: clinical, histological and immunohistochemical studies and a physiopathogenic hypothesis

BACKGROUND AND AIM OF THE STUDY

Cardiac papillary fibroelastoma (CPF) is a rare and histologically benign tumor, but may have a malignant propensity for life-threatening complications; thus, surgical removal is justified. Case histories were reviewed of four patients who underwent surgical management after diagnosis of CPF located on aortic (n = 2) or mitral (n = 2) valves. Our aim was to provide explanations for the clinical diversity of the lesions and, using histological and immunohistochemical methods, to hypothesize the genesis of these tumors.

METHODS

Among four patients with a diagnosis of valvular CPF, two had previous and recent history of neurological embolic symptoms with small echographically located tumors attached to the ventricular side of aortic cusps. Two other patients (one with paroxysmal atrial fibrillation, one with no neurological or rhythmically related stroke) had CPFs located on the posterior or anterior mitral leaflets.

RESULTS

Surgical excision was performed with a conservative valve-sparing approach. Histological and specific immunohistochemical (IHC) studies were conducted on all samples. The postoperative course was uneventful, and histological analysis confirmed the diagnosis of CPF with typical fronds characterized by three successive layers. In the first two patients there was correlation between neurological events and the presence of thrombus aggregated on the injured superficial endothelial layer. In the other patients, no endothelial damage or thrombus was found. IHC studies showed dysfunction of the superficial endothelium, a centrifugal mesenchymal cellular migration arising from the central layer to the superficial layer with differentiation steps, the presence of dendritic cells in the intermediate layer, and remnants of cytomegalovirus (CMV) in the intermediate layer.

CONCLUSION

Despite their benign histological aspect, and independent of their size, CPFs justify surgical excision because of their high potential to systemic embolization. In most cases, valve sparing management is possible with no observed recurrence after complete excision. The presence of dendritic cells and CMV strongly suggests the possibility of a virus-induced tumor, therefore evoking the concept of a chronic form of viral endocarditis.

A single endotoxin injection in the rabbit causes prolonged blood vessel dysfunction and a procoagulant state

OBJECTIVES

To determine the duration of vascular blood vessel dysfunction and coagulation abnormalities after administration of endotoxin in a nonlethal septic rabbit model.

DESIGN

Randomized, controlled, interventional trial.

SETTING

University animal laboratory.

SUBJECTS

A total of 30 male New Zealand White rabbits, randomly assigned to one of two groups.

INTERVENTIONS

Male New Zealand White rabbits were randomly divided into control or lipopolysaccharide (LPS) (0.5 mg/kg iv bolus Escherichia coli endotoxin)-treated groups. Metabolic acidosis and coagulation activation confirmed the presence of septic shock. The abdominal aorta was removed at 24 hrs (day 1), day 5, or day 21 after LPS injection. Immunohistochemical staining for an endothelial cell marker (PECAM-1/CD31) was performed to assess endothelial injury. Endothelium-dependent vascular relaxation was analyzed by in vitro vascular reactivity studies. Responses to acetylcholine, to calcium ionophore (A-23187), and to sodium nitroprusside were studied. In addition, arterial blood samples were collected on day 1, day 5, and day 21 for measurement of clotting factors and tissue factor activity.

MEASUREMENTS AND MAIN RESULTS

LPS injection resulted in endothelial injury, with loss of approximately 25% of the endothelial area on day 5, which disappeared on day 21. LPS injection also caused a significantly reduced relaxation response to acetylcholine (44.9% +/-9.9% vs. 76.5%+/-5.4% for the control group; p < .005), which was restored on day 21. In contrast, vascular relaxation in response to A-23187 and sodium nitroprusside was not altered. A significant decrease in the platelet count was observed on day 1, associated with a decrease in factors II and V. On day 5, platelet count and factors II and V were corrected in conjunction with an elevated monocyte tissue factor activity in LPS-injected rabbits. On day 21, coagulation abnormalities were corrected.

CONCLUSIONS

A single endotoxin injection in the rabbit was responsible for prolonged aortic endothelial cell dysfunction, as well as a prolonged procoagulant state. The latter is a potential trigger for disseminated intravascular coagulation. Importantly, these features are associated with normalization of conventional biological evidence of septic shock.

Regional capnometry with air-automated tonometry detects circulatory failure earlier than conventional hemodynamics after cardiac surgery

Gastrointestinal automated online air tonometry has been proposed for monitoring gastric perfusion in patients at risk of circulatory failure (CF) after cardiopulmonary bypass. In this study, CF was prospectively defined as the requirement for vasoactive support to maintain mean arterial pressure > or = 70 mm Hg after optimization of preload. Hemodynamic variables--oxygen (O2) delivery (DO2), O2 uptake (Vo2), venous-to-arterial [P(v-a)CO2], gastric-to-arterial [P(r-a)CO2], and gastric-to-end-tidal [P(r-et)CO2]Pco2 gap-were retrospectively compared in 14 patients with or without CF during a 12-hr postbypass period (HO-H12). In contrast to patients without CF (n = 7), in patients with CF (n = 7) increased VO2 was not associated with an increase in DO2. P(r-a)CO2 was larger at H0 in CF patients and was the only variable that differed between the two groups. P(v-a)CO2 did not vary significantly in both groups, whereas P(r-a)CO2 increased to a larger extent from H0 to H12 in patients with CF, suggesting selective gastrointestinal hypoperfusion in this group. P(r-et)CO2 provided comparable information to P(r-a)CO2. Hospital length of stay was 4 days longer (P < 0.05) in patients with CF. Increased P(r-a)CO2 and P(r-et)CO2, as monitored with automated air tonometry, were associated with rapid occurrence of CF and prolonged hospital stay after cardiac surgery.

IMPLICATIONS

Regional and automated capnometry may be used noninvasively to identify patients at risk of circulatory failure after cardiopulmonary bypass earlier than with conventional variables.

Intraoperative computerized mapping of ventricular tachycardia: differences between anterior and inferior myocardial infarctions

INTRODUCTION

Although direct ventricular tachycardia (VT) surgery has been shown to be effective for treatment of inferior myocardial infarction (MI), the differences in the arrhythmia substrates compared to anterior MI have not been systematically delineated. We sought to compare operative procedures and VT substrates between anterior and inferior MI locations.

METHODS AND RESULTS

Computerized mapping was performed in 30 patients with a 128-electrode system using epicardial sock and transatrial left ventricular endocardial balloon arrays, followed by combined endocardial resection and cryoablation. At surgery, there were 51 and 34 different VTs in 18 patients with anterior MI and 12 patients with inferior MI, respectively. The proportion of aneurysms was lower in inferior MI (25% vs 78%, P = 0.008). Total activation times accounted for 65% +/- 23% and 50% +/- 22% of the VT cycle length in anterior and inferior infarcts, respectively (P = 0.005). Complete superficial reentry was identified in 12 VTs related to anterior infarcts and in only two VTs associated with inferior infarction (P = 0.038). Involvement of papillary muscles occurred in two patients with inferior MI. Patients with inferior infarcts received more cryolesions and required epicardial cryolesions or mitral valve replacement more frequently, and their operative mortality was greater (2/12 vs 0/18). Noninducibility rate (89.3%) and 2-year survival (76% +/- 8%) did not differ according to infarct location.

CONCLUSION

VT associated with inferior MI can be ablated successfully; however, the substrate is more complex, with frequent participation of intramural layers rendering the ablative procedure more difficult.

Acute aortic endocarditis with annular destruction: assessment of surgical treatment with cryopreserved valvular homografts

BACKGROUND AND AIM OF THE STUDY

Valve ring abscesses in acute infective aortic endocarditis have a low, though not insignificant, prevalence. Surgical treatment with implantation of prosthetic valves may lead to major life-threatening complications, such as recurrent endocarditis and partial or complete prosthetic dislocation. Valvular homografts may offer a higher resistance to recurrent infection and have thus become recognized as an excellent and safe substitute for orthotopic left ventricular outflow reconstruction.

METHODS

Between May 1991 and July 1996, 25 patients underwent surgical treatment for aortic endocarditis with annular destruction. Staphylococcus spp. were present in 32% of patients and Streptococcus spp. in 48%. Seven aortic valve replacements (AVR) and 18 aortic root replacements (ARR) were performed using cryopreserved valvular homografts. All grafts were implanted in the subannular position.

RESULTS

The overall outcome was good in 23 patients, two died in the early postoperative period. Mean follow up was 38 +/- 18 months (range: 14 to 76 months). No recurrence of endocarditis was detected and no significant alterations of the implants were described. Transvalvular gradients were significantly lower in ARR patients than in AVR patients.

CONCLUSIONS

Despite the severity of the tissue damage, cryopreserved homografts, when implanted in the subannular position, constitute a safe and reproducible surgical treatment of aortic endocarditis with annular involvement.

Aortic root replacement with a pulmonary autograft in young adults: medium-term results in 70 patients

BACKGROUND

Pulmonary autograft aortic valve replacement has been introduced in our institution in selected adult patients in light of the known disadvantages and limitations of conventional prosthetic valves.

METHODS

We prospectively evaluated the use of the pulmonary autograft in a series of 70 young adults (31.2+/-8.7 years, range 16 to 49 years) operated on from March 1992 to April 1997 with aortic root replacement only.

RESULTS

There were no in-hospital deaths and two noncardiac-related late deaths during follow-up of up to 62 months (mean 33 months). Thromboembolic complications were not observed. One patient required reoperation for infective endocarditis 4.3 years after surgery. Discharge echo-Doppler studies showed normal autograft and allograft valve function. Serial echo-Doppler studies showed no significant progression of aortic insufficiency and no dilatation of the autograft. A severe stenosis of the pulmonary allograft developed in 1 patient.

CONCLUSION

Aortic root replacement with a pulmonary autograft, although more complex than conventional prosthetic valve replacement, is a safe, effective, and reproducible procedure in properly selected adult patients. Long-term results remain to be evaluated.

Relationship between CMV and graft rejection after heart transplantation

This study, which included 153 heart transplant patients, was designed to determine whether the cytomegalovirus (CMV) status of both donor and recipient may influence graft rejection. The follow-up was 1 year and they all received the same triple-drug immunosuppressive regimen with induction (antilymphocyte serum). There was no difference in the total rejection rate, but an increase in repeated rejection rate was shown in transplant recipients with hearts from CMV seropositive donors (P < 0.05). These data strongly suggest the impact of CMV in enhancement but not in induction of rejection. To prevent iterative rejection in the CMV seropositive donor group, antiviral therapy could be proposed during enhancement of antirejection therapy.

Detection of enteroviral RNA by polymerase chain reaction in endomyocardial tissue of patients with chronic cardiac diseases

Enteroviruses are suspected to be etiologic agents in myocarditis and cardiomyopathy. The prevalence of enteroviral (EV) heart infection in patients with chronic cardiomyopathy was determined through detection of specific EV genomic sequences using reverse transcription and polymerase chain reaction (RT-PCR) followed by slot blotting. Endomyocardial biopsies from the explanted hearts of 19 patients with dilated cardiomyopathy (DCM) and 14 patients with chronic coronary disease (CCD) were examined. EV genome was detected in 11 of 19 patients with DCM and in 8 of 14 patients with CCD. Ventricular biopsies from the control group, which included 35 healthy heart patients and 33 patients with myocardial infarction, were negative by EV RT-PCR. The percentage of patients showing presence of EV-RNA was almost similar in the DCM (57.9%) and CCD (57.1%) groups. The present study demonstrates that enterovirus RNA sequences persist in the myocardium in a significant proportion of patients suffering from end-stage ischaemic and dilated cardiac diseases and supports the hypothesis of a possible direct link between EV infection and the pathogenesis of chronic heart disease.

Detection of enterovirus-specific RNA sequences in explanted myocardium biopsy specimens from patients with dilated or ischemic cardiomyopathy

Enteroviral RNA (EV-RNA) was detected in endomyocardial tissue by means of retrotranscription and polymerase chain reaction (RT-PCR) followed by slot-blot hybridization. The myocardial biopsy specimens studied were taken at the time of heart transplantation from 15 patients with dilated cardiomyopathy (DCM) and from 10 patients with ischemic cardiomyopathy (ICM). Specimens from 18 (72%) of the 25 patients were positive for EV-RNA, whereas no control specimens (myocardial specimens from 29 healthy organ donors and atrial specimens from 15 patients with acute myocardial infarction treated by anatomic bypass) yielded evidence of EV-RNA. The rates of EV-RNA detection for the two groups requiring heart transplantation did not differ significantly (66.7% vs. 80.0%; chi 2 test). Our findings support a link between enteroviral infection in both DCM and ICM and suggest a pathogenic role for the enteroviruses.