Current Medical Imaging - Volume 5, Issue 1, 2009

Again, the first issue of CMIR in 2009 demonstrates an important role of advanced MRI and utrasonographic methods in visualizing Alzheimer's plaque, the artery of Adamkiewicz and Langerhans cell histiocytosis, in diagnosing ischemic stroke and soft tissue vascular malformation and tumors, as well as for the translational medical research as cellular imaging tools. The most common form of dementia among older people is Alzheimer's disease, and about 4.5 million Americans suffer from this condition, which usually begins after 60 years old. The formation of brain plaque may be the first step toward Alzheimer's disease, and it can happen within a day. The plaque did not go away but it stabilized within a week. Soon after the plaques appear, brain cells start to distort and specialized cells called microglias appear on the scene. N. Braakman et al. review some of the current developments in visualizing the plaques in mice and highlight the future impact on the drug discovery. They also discuss potential applications of these methods in human patients. In human anatomy, the artery of Adamkiewicz is the largest anterior segmental medullary artery. It typically arises from a left posterior intercostals artery, which branches from the aorta, and supplies the lower two thirds of the spinal cord via the anterior spinal artery. When damaged or obstructed, it can result in anterior spinal artery syndrome, with loss of urinary and fecal continence and impaired motor function of the legs. Therefore, it is very important to identify the location of this artery when treating an abdominal aortic aneurysm. H. Hyodoh et al. review the challenges surrounding the current imaging and clinical workup of the artery of Adamkiewicz and provide a framework for the potential role of MRI and CT to prevent the spinal complications. Langerhans cell histiocytosis is a rare disease involving clonal proliferation of langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes. Clinically, its manifestations range from isolated bone lesion to multisystemic disease. It is traditionally divided into three groups: unifocal (eosinophilic granuloma), multifocal unisystem (mostly in children) and multifocal multisystem (Letterer-Siwe disease). T.Y. Moon et al. classified this into three types histopathologically and correlated with MRI findings for the staging purposes. Personalized treatment using modified or genetically engineered stem cells is becoming a reality in the clinical medicine. Hematopoietic, stromal aand organ specific stem cells are under evaluation of cell-based therapies for cardiac, neurological, autoimmune and other disorders. It is important to track the temporal and spatial homing of these cells to target tissues by noninvasive methods. It is also necessary to determine the transplanted cell's engraftment efficiency and functional capability. A. S. Arbab et al. discuss the methods to transform cells into probes for in vivo imaging as well as clinical applicability of cellular imaging fro translational medical research.

The presence of amyloid plaques in the brain is one of prominent histological features of Alzheimer's disease. However, imaging of amyloid plaques in vivo in humans is not yet feasible. Recent technical advances in high resolution magnetic resonance imaging (MRI) methods in mice have enabled not only the detection of amyloid plaques in vivo but also allowed to monitor the development of these plaques with age in the same animals. Further technical improvements to visualize small plaques at early stages at ultrahigh magnetic fields are underway. This review summarizes some of the current developments in visualizing AD plaques in vivo in mice and highlights their future impact on drug discovery. Furthermore potential application and challenges of translation of these methods for visualizing plaques in human are discussed.

It is necessary to assess the branching level of the artery of Adamkiewicz (AKA) before repair of the thoracoabdominal or descending thoracic aorta. Spinal damage (paraplegia/paraparesis) is a severe complication that can arise during such surgery, as a result of ischemia, and the risk of such damage is therefore a limitation of this procedure. Irreversible spinal complications can drastically decrease a patient's quality of life. Recent studies have demonstrated the feasibility and advantages of the assessment of the AKA with both magnetic resonance (MR) angiography and computed tomographic (CT) angiography. In this article, the authors review the challenges surrounding the current imaging and clinical work-up of the AKA and provide a framework for understanding the potential role of MR and CT in a pre-operative setting for the prevention of the spinal complications.

Objective: The purpose of the study was to determine the stage of magnetic resonance images (MRI) of Langerhans cell histiocytosis (LCH). Materials and Methods: The MR images of 16 patients with a histopathologically proven diagnosis of LCH by curettage biopsy were analyzed retrospectively. There were 9 female and 7 male patients, age range 1-36 years, mean age 8.7 years. Lesions were located in the humerus (n=5), the femur (n=4), the pelvic ilium (n=3), the tibia (n=2), the scapula (n=1), and the metacarpal (n=1). We classified ‘type A’ as full hypercellularity lesion, ‘type B’ as peripheral hypercellularity and central fibrosis, and ‘type C’ as reduced cellularity on MRI of LCH. Histopathologic evolution of LCH comprised four different phases. Results: Four of 16 patients, who were reconfirmed to the first incipient phase of LCH histopathologically, revealed as one ‘type A’, two ‘type A and B’, and one ‘type B’. Eight patients with the second phase revealed seven ‘type B’ and one ‘type B and C’ on the MRI. One patient with the third phase revealed ‘type B’. Three patients with the last phase revealed all ‘type C’. The MRI findings are well correlated with the histopathologic findings of LCH.

Personalized treatment using stem, modified or genetically engineered, cells is becoming a reality in the field of medicine, in which allogenic or autologous cells can be used for treatment and possibly for early diagnosis of diseases. Hematopoietic, stromal and organ specific stem cells are under evaluation for cell-based therapies for cardiac, neurological, autoimmune and other disorders. Cytotoxic or genetically altered T-cells are under clinical trial for the treatment of hematopoietic or other malignant diseases. Before using stem cells in clinical trials, translational research in experimental animal models are essential, with a critical emphasis on developing noninvasive methods for tracking the temporal and spatial homing of these cells to target tissues. Moreover, it is necessary to determine the transplanted cells, engraftment efficiency and functional capability. Various in vivo imaging modalities are in use to track the movement and incorporation of administered cells. Tagging cells with reporter genes, fluorescent dyes or different contrast agents transforms them into cellular probes or imaging agents. Recent reports have shown that magnetically labeled cells can be used as cellular magnetic resonance imaging (MRI) probes, demonstrating the cell trafficking to target tissues. In this review, we will discuss the methods to transform cells into probes for in vivo imaging, along with their advantages and disadvantages as well as the future clinical applicability of cellular imaging method and corresponding imaging modality.

Cerebrovascular diagnostics are increasingly important in stroke therapy, especially in cases when the time window for IV rtPA has exceeded, in follow-up and secondary prevention of ischemic stroke. Transcranial color-coded duplex sonography (TCCS), a noninvasive and flexible method for vascular and parenchymal imaging of the adult brain, and is considered complementary to CT- and MR-Angio as the investigator depicts intracranial hemodynamics including occlusions, stenosis and the sufficiency of collateral flow. After an introduction to the general technical requirements of the ultrasound system and the defined transcranial image planes important for stroke diagnostics we focus on intracranial arterial vessel occlusions and stenosis important for cerebral ischemia work-up. UCA have had a tremendous impact on TCCS application and are used in cases of unfavorable acoustic bone windows resulting in superior signal-to-noise and yield high and fast diagnostic confidence. In addition, new developments in ultrasound signal processing and transducer technology, such as harmonic B-mode and contrast burst imaging amongst others, take advantage of microbubble specific properties which allow for increased signal retrieval as well as separation of linear and non-linear acoustic responses. Bedside ultrasound perfusion sonography has gained special attention and first encouraging results have visualized and quantified perfusion defects in acute stroke patients. This review is aimed to guide the unexperienced sonographer to valid and important findings in intracranial cerebrovascular disease.

Soft tissue vascular malformations and tumours are a heterogeneous group of lesions. Some of them may only be transient, such as vascular birthmarks in newborns. In about one percent of children however a vascular soft tissue lesion needs further diagnostic work-up. Angiomateous lesions may even have a malignant potential and so an exact assessment is especially needed to define the prognosis of a lesion, as well as for planning of efficient treatment. Highresolution ultrasound (HR-US) together with Color Doppler ultrasound (CDUS) and spectral wave analysis (SWA) - at least as a first line modality - allow for an exact and reliable differentiation of such lesions in most cases. In addition HRUS is well tolerated and is suitable for follow-up assessment especially in children. Besides its diagnostic impact, HR-US is also well suited for guided interventional procedures. HR-US guided percutaneous sclerotherapy seems very promising in this context also with regard to other therapeutic options. In this review the diagnostic importance and value of HR-US are discussed in detail.

Cirrhosis and portal hypertension are common diagnostic findings in the Western world. The aetiology is variable, however alcohol abuse and hepatitis are the commonest causes. Ultrasound is usually the first diagnostic modality to be used. It is easy to find, safe, radiation-free and cheap. Although computed tomography, magnetic resonance and biopsy may be needed for diagnosis and follow up, ultrasound will always be used for initial assessment and in many cases will solve the diagnostic problem. We review the findings on B-mode and Doppler, as well as contrast enhanced ultrasound, according to a protocol which should be followed in order to evaluate a patient with cirrhosis and portal hypertension.