Cancer imaging: novel concepts in clinical magnetic resonance imaging

Abstract. Kwee TC, Takahara T, Klomp DWJ, Luijten PR. (University Medical Center Utrecht, Utrecht, The Netherlands). Cancer imaging: novel concepts in clinical magnetic resonance imaging. J Intern Med 2010; 268 : 120–132. Cancer is a major public health problem in the Western world. Imaging is of crucial importance in oncology, because it may reduce cancer‐related morbidity and mortality. To improve tumour evaluation, there is a need for functional imaging modalities that go beyond gross assessment of anatomical abnormalities and allow visualization and quantification of biochemical processes in vivo. Magnetic resonance imaging (MRI) not only provides anatomical information, but also offers a wide range of functional sequences that may aid the evaluation of cancerous lesions. Furthermore, MRI provides the opportunity to guide and monitor anticancer therapies noninvasively. The aim of this review is to highlight some of the most promising developments of MRI in the functional assessment of cancer and the guidance and monitoring of (novel) anticancer therapies.     

Idiopathic anterior hypopituitarism: magnetic resonance imaging and clinical correlation.

We describe the anatomical abnormalities in the hypothalamic-pituitary region revealed by magnetic resonance imaging (MRI) in 10 patients, 8 men and 2 women, affected by idiopathic anterior hypopituitarism (IAH). In all cases contiguous sagittal and coronal T-1 weighted images were obtained. In 9 patients the high-intensity posterior lobe was missing, in almost all patients the pituitary stalk was thin and/or transected, and in 8 a bright T-1 nodule was detected at the infundibular apex, near the tuber cinereum, in the median eminence. None had diabetes insipidus. MRI proves to be very useful in understanding the etiopathogenesis of IAH.     

Pallidal hyperintensity on magnetic resonance imaging in cirrhotic patients: clinical correlations.

Patients with cirrhosis show increased signal intensity in the globus pallidus on T1-weighted magnetic resonance imaging of the brain. This abnormal appearance of the basal ganglia has been related to the severity of liver failure and to the presence of portal-systemic shunting, although its cause and clinical significance remain unknown. We prospectively assessed the metabolic, neurological and neuropsychological statuses of 30 stable cirrhotic patients and correlated these clinical variables with computed measurements of globus pallidus signals. Some metabolic variables denoting disease severity appeared to be significantly related to image changes, although the strongest association was found with plasma ammonia levels. After adjustment for ammonia level, on multiple regression analysis, the other variables were not significant. Furthermore, pallidal changes were associated with specific neurological symptoms and neurological functions, symptoms and functions that also had a significant correlation with ammonia levels. Our findings suggest that globus pallidus signal abnormality could arise as a marker of brain impairment related to hyperammonemia.     

Pacing for adult patients with left atrial isomerism: efficacy and technical considerations.

AIM: Left atrial isomerism (LAI) is an uncommon congenital heart disease, which is combined with a range of intracardiac abnormalities. Atrial arrhythmia is common in LAI. We hypothesized that permanent pacing will decrease arrhythmia recurrence in adult patients with LAI. METHODS AND RESULTS: Patients with LAI and permanent pacing were identified from the Royal Brompton Adult Congenital Heart Database. Hospital records were reviewed, and patients' current status was assessed with clinic reviews including standard and Holter ECGs, and transthoracic echocardiograms. Four patients who underwent permanent pacing at the age of 27.5+/-11.7 years fulfilled inclusion criteria, namely permanent pacing in the setting of LAI. All 4 had sick sinus syndrome-with sustained supraventricular arrhythmia in 3-requiring several hospitalizations for arrhythmia management prior to pacing. All 4 patients remained free of clinical arrhythmia and hospital admission at a mean follow-up of 67.0+/-59.5 months from pacing. The latest ECG revealed paced rhythm in all. NYHA functional class remained stable. There were no pacemaker related complications at implantation or during follow-up. CONCLUSION: Adults with LAI benefit from pacemaker implantation, which reduces recurrence of supraventricular tachycardia and maintains atrioventricular synchrony. Future studies need to determine the preferred pacemaker mode and optimal timing for pacing.     

Automated external defibrillators: technical considerations and clinical promise.

Early defibrillation is the most important determinant of survival for victims of cardiac arrest due to ventricular fibrillation. The automated external defibrillator (AED) was developed as the result of the American Heart Association's Public Access Defibrillation initiative. The goal of this initiative is to place AEDs in strategic locations so that laypersons with minimal training could promptly defibrillate victims of cardiac arrest. Because of changes in design and the use of alternative waveforms for defibrillation, the modern AED is compact and portable, simple to use, and highly efficacious; in addition, it requires little maintenance. Automated external defibrillators have been used successfully by traditional and nontraditional responders as well as laypersons. In special environments, such as casinos and commercial aircraft, AEDs have performed particularly well. State and federal legislation has eased concerns about AED use by extending legal protection to AED users under Good Samaritan laws. Since the experience continues to be positive, AEDs are being used in increasingly diverse community locations, and public awareness is growing. The American Heart Association's initiative is progressing rapidly.     

Safety considerations for magnetic resonance imaging of pacemaker and ICD patients

Summary Magnetic resonance imaging (MRI) has evolved as an important diagnostic tool in medicine. However, due to safety concerns the presence of an implanted cardiac pacemaker is considered to be a contraindication to MRI in most medical centers. Previous in vitro and in vivo studies showed that strong electromagnetic fields in the MRI environment may cause asynchronous pacing, inhibition of a demand pacemaker, induced currents in the pacemaker system and pacing of the heart, or potential risk of thermal myocardial injury around the pacing lead tip. ICDs in addition are not able to charge and apply a therapy in the strong magnetic field. There are reported lethal consequences of MRI in patients with pacemakers. However, there are also recent reports of small series of pacemaker patients who have safely undergone MRI. At present time, non-MRI modalities should be considered, whenever possible, to make a diagnosis in pacemaker recipients. If other imaging modalities are not adequate, MRI at low field strengths (0.5 Tesla or less) with careful monitoring and preparation for adverse events may be considered only in experienced centers. The device should be programmed to an asynchronous, or if possible to a non-pacing mode, during MRI. Pacemaker mode changes, inappropriate pacing behavior due to induced voltages, and localized heating at the lead tip are the primary issues that remain to be fully investigated in future studies.This work is supported by a grant from the Bakken Research Center, Medtronic Inc., Maastricht, the Netherlands.     

Updating magnetic resonance imaging of small bowel：Imaging protocols and clinical indications

High soft tissue contrast resolution,acquisition of multi-planar images and the possibility to obtain functional information make magnetic resonance an interesting imaging technique to evaluate the small bowel disease.The absence of ionizing radiation is an important feature of magnetic resonance imaging（MRI） examinations because inflammatory diseases such as Crohn＇s disease（CD） are studied most frequently,which are prevalent among children and young adults.MRI,using modern equipment and a rigorous technical approach,can offer detailed morphologic information and functional data on the small bowel.This article discusses the MRI protocols for small bowel and the MR imaging findings of small bowel diseases,such as CD and small bowel neoplasms.     

A clinical cardiovascular magnetic resonance service: operational considerations and the basic examination

Cardiovascular magnetic resonance (CMR) is now considered the "gold standard" for the assessment of regional and global systolic function, myocardial infarction and viability, and congenital heart disease. At specialized centers, CMR has become a clinical workhorse for the evaluation of ischemic heart disease and for heart failure and cardiomyopathies. Despite this versatility, general acceptance of CMR in cardiovascular medicine has progressed slowly. This article provides a basic understanding of important operational considerations when starting a CMR service and describes a conceptual framework of the components of a CMR examination.     

Advances in clinical applications of cardiovascular magnetic resonance imaging

Cardiovascular magnetic resonance (CMR) is an evolving technology with growing indications within the clinical cardiology setting. This review article summarises the current clinical applications of CMR. The focus is on the use of CMR in the diagnosis of coronary artery disease with summaries of validation literature in CMR viability, myocardial perfusion, and dobutamine CMR. Practical uses of CMR in non-coronary diseases are also discussed.     

Coronary angioplasty 1985: technical and clinical considerations

As the result of progressive improvements in equipment design and operator technique, PTCA has become an increasingly common alternative to surgical revascularization in the patient with coronary artery disease, achieving favorable symptomatic relief with less patient discomfort, disability and expense. As the scope of PTCA broadens to include multivessel disease and acute ischemic syndromes, however, it is important to continually evaluate it against medical therapy and bypass surgery, and thereby define those patient subgroups for whom PTCA is the treatment of choice.     

Myocardial perfusion imaging: clinical experience and recent progress in radionuclide scintigraphy and magnetic resonance imaging

In the past 20 years, radionuclide scintigraphy has proven to be a sensitive clinical tool in the assessment of myocardial perfusion abnormalities. Magnetic resonance imaging may also be used to study myocardial perfusion, but its potential value still has to emerge in the clinical setting. This review addresses the potential and achievements of both methods in clinical cardiology.     

Dual energy subtraction digital radiography: technical considerations, clinical applications, and imaging pitfalls

Emerging applications in digital radiography offer exciting advances in the evaluation of lung disease. Dual energy subtraction techniques have been recognized as a promising technique in the detection and characterization of pulmonary nodules. This essay will demonstrate a significantly expanded diagnostic role in the assessment of cardiothoracic disease with dual energy subtraction and digital radiography.     

Endosonography and endoscopic magnetic resonance imaging.

Endosonography is an important modality for the diagnosis and staging of oesophageal, gastric, colorectal and pancreatobiliary malignancy. It is also recognized as a reliable method for the evaluation of submucosal tumours of the gastrointestinal tract, for differentiating benign lesions from giant gastric folds, and for the localization of pancreatic endocrine tumours. The latest development, that of endosonographic fine-needle aspiration, provides for the cytological diagnosis of gastrointestinal tumours. This new technique may also be used for endoscopic therapy. High-frequency probes can be used to make a more accurate diagnosis of superficial carcinoma of the gastrointestinal tract, for three-dimensional imaging of gastrointestinal tumours and for intraductal ultrasonography of the bile duct and pancreatic duct. Endoscopic magnetic resonance imaging provides information not obtainable with endosonography or other modalities. It has high potential in the diagnosis and staging of gastrointestinal and pancreatobiliary tumours.     

Osteoarthritis and magnetic resonance imaging: potential and problems.

To date, MRI has primarily been used to study anatomical changes, and at a resolution that makes detailed analysis of focal change difficult. This is primarily because cost limits the development and use of tailor made research systems. The detailed analysis of soft tissue, cartilage, and bone marrow images should provide a fruitful non-invasive method to study OA. However, the development of MRI methods to study movement, diffusion and perfusion, and the spatial localisation of spectroscopic information, promises a revolution in the study of the living joint in man.     

Update in cardiac imaging techniques. Echocardiography and magnetic resonance imaging

This article is a review of the main developments in cardiac imaging techniques reported in publications during 2005. Recent advances in digital technology have led to steadily increasing reliance on imaging techniques in the management of cardiovascular disease. We discuss advances in two techniques that fall under the remit of the echocardiography working group: echocardiography and magnetic resonance imaging.     

Tomographic plaque imaging with CT: technical considerations and capabilities

X-ray computed tomography (CT) is widely available in the world and has the ability to provide high-definition, thin-section imaging of any body part. In particular, CT over the past decade has been shown in numerous publications to allow for quantitation of coronary calcification, a proven surrogate for coronary artery atheromatous plaque. Electron beam tomography (EBT) and multidetector CT (MDCT) have been studied for these purposes. However, there are methodological differences between types of CT scanners and precision of calcium scoring is a function of their individual technical capabilities and limitations. These technical aspects are detailed here. Although MDCT has shown considerable improvements in recent years, EBT remains the clinical reference standard for noninvasive definition of atherosclerotic plaque.     

Cervicomediastinal magnetic resonance imaging in persistent or recurrent papillary thyroid carcinoma: clinical use and limits.

Cervicomediastinal magnetic resonance imaging (MRI) was evaluated in 13 consecutive persistent or recurrent papillary thyroid carcinoma (PTC) patients, previously treated by total thyroidectomy and radioiodine ablation. All had elevated thyroglobulin (Tg) levels and were therefore submitted to a new therapeutic radioiodine dose followed by a posttherapeutic whole-body scan (131I-WBS) and subsequent MRI. Patients with known distant metastases were excluded from the study. Group 1 included 7 patients with a negative 131I-WBS, whereas cervical and/or mediastinal 131I-uptake was evidenced in the other 6 patients (group 2). MRI was thus compared to 131I-WBS, and additionally in 8 reoperated cases, to histology. MRI was positive in 11 of 13 (85%) patients, corresponding to 23 of 55 (41.8%) histologically confirmed sites. In group 1, MRI was positive in 5 of 7 patients, with a sensitivity of 47% (15/32 histologically positive sites), allowing appropriate indication of surgery: 4 neck surgery, and 1 mediastinal dissection because of too distant lymph node foci. In group 2, MRI always showed more localization than 131I-WBS; histology was obtained in 3. Because all the foci located in the mediastinal area (0.8 to 1.8 cm) were histologically confirmed (7/7 sites), MRI avoided underestimation of surgery in the 8 reoperated patients. However, additional images were also observed corresponding to a normal thymus, a small neuroma or inflammatory lymph nodes, but pretracheal and very small nodes (less than 0.5 cm) were missed. In conclusion, although less specific than radioiodine scintigraphy, MRI can detect local persistent or recurrent PTC, and seems particularly effective for evaluation of mediastinal involvement.     

The emerging clinical role of cardiovascular magnetic resonance imaging

Starting as a research method little more than a decade ago, cardiovascular magnetic resonance (CMR) imaging has rapidly evolved to become a powerful diagnostic tool used in routine clinical cardiology. The contrast in CMR images is generated from protons in different chemical environments and, therefore, enables high-resolution imaging and specific tissue characterization in vivo, without the use of potentially harmful ionizing radiation.CMR imaging is used for the assessment of regional and global ventricular function, and to answer questions regarding anatomy. State-of-the-art CMR sequences allow for a wide range of tissue characterization approaches, including the identification and quantification of nonviable, edematous, inflamed, infiltrated or hypoperfused myocardium. These tissue changes are not only used to help identify the etiology of cardiomyopathies, but also allow for a better understanding of tissue pathology in vivo. CMR tissue characterization may also be used to stage a disease process; for example, elevated T2 signal is consistent with edema and helps differentiate acute from chronic myocardial injury, and the extent of myocardial fibrosis as imaged by contrast-enhanced CMR correlates with adverse patient outcome in ischemic and nonischemic cardiomyopathies.The current role of CMR imaging in clinical cardiology is reviewed, including coronary artery disease, congenital heart disease, nonischemic cardiomyopathies and valvular disease.