Perfusion scanning

About: Perfusion scanning is a research topic. Over the lifetime, 9496 publications have been published within this topic receiving 223860 citations. The topic is also known as: perfusion imaging.

Clinical MR neuroimaging : diffusion, perfusion, and spectroscopy

Abstract: Magnetic resonance (MR) physiologic and functional techniques, which augment imaging, can now be performed during most clinical MR imaging examinations. This book’s aim is to present appropriate clinical applications of and to discuss interpretation of results from diffusion imaging, perfusion imaging, and spectroscopy. The editors have attempted to provide a reference for clinical practice with broad applications of functional imaging. The editors are longtime researchers in MR imaging. Gillard and Waldman are neuroradiologists and Barker is an imaging scientist. They have assembled an expert international team of chapter authors. An insightful introduction is provided by R. Nick Bryan, a well-known neuroradiologist experienced with physiologic and functional MR imaging. There are 46 chapters within seven clinical disease sections: cerebrovascular, neoplastic, infection/ inflammatory, epilepsy, neurodegenerative/psychiatric, trauma, and pediatric disorders. There is a six-page list of abbreviations. The abbreviation rCBF, which for decades had been defined as regional cerebral blood flow, has been defined in recent journal articles and now in this book as relative cerebral blood flow, unaccompanied by any explanation of the change of established nomenclature. The term cerebral blood flow (CBF) is subsequently defined separately. Chapter 7 presents deconvolution formulas to calculate CBF values. However, a reader not already familiar with the formulas will not know if they produce true relative CBF values in units of milliliters of blood per 100 cm of brain tissue per minute, the most precise blood flow value. Chapter 8 contains mentions of “regional blood flow” without an explanation of whether regional CBF—or another CBF value—is meant. It is unfortunate that this definitive textbook of neuroimaging physiology does not outline these discrepancies for readers. A limitation of this text is the emphasis on the advances in MR imaging techniques without much in-depth discussion of advanced computed tomographic (CT) techniques such as CT perfusion imaging. Chapter 8 compares MR perfusion imaging with positron emission tomography (PET) and xenon CT, yet mentions nothing about CT perfusion imaging, which is considered by many to be the most efficient way to immediately measure regional CBF, CBF volume, and mean transit time (MTT). CBF volume and MTT measurements without regional CBF measurements dominate reports of clinical MR imaging. CBF volume correlates well with diffusion-weighted MR imaging defects whether done with CT perfusion or MR perfusion. MTT on its own is nonspecific; it reflects the time for blood to arrive, but it does not always reflect the adequacy of blood supply. For example, patients with proximal occlusions and excellent collateral vessels without ischemia (eg, patients with acute stroke) may have markedly delayed MTT values. Chapter 10 describes the advantages of CT perfusion imaging: It is simpler and much quicker to perform than MR perfusion imaging, and is not associated with an unfriendly magnet environment. However, it takes more skill to interpret early infarction on CT images than on diffusion-weighted MR images. Readers who prefer to learn complex new material by repetition will appreciate this book, which is organized according to diseases. Specific techniques, such as MR spectroscopy, are explained multiple times across different chapters. Various peaks on MR spectra become familiar by repetition. Commercial software that identifies various chemical peaks is currently available, which further facilitates the use of MR spectroscopy in clinical practice. Other MR techniques such as tensor imaging, spectroscopy, and functional mapping have no competition from CT. Techniques such as PET are not prevalent in clinical departments, and the future seems to lie with MR for all but time-limited situations. The physiologic and functional MR techniques described in this book are here to stay and already used in the field, beyond academic sites. The editors achieve their goal of providing detailed reference tutorials for neuroimagers to understand current uses. This book is worth the cost as a reference for those who do neuroimaging or refer patients for neuroimaging studies. Reviewed by Allan J. Fox, MD BOOK REVIEWS

Laser‐polarized 3He as a probe for dynamic regional measurements of lung perfusion and ventilation using magnetic resonance imaging

Abstract: Magnetic resonance imaging (MRI) using laser-polarized noble gases, such as (129)Xe and (3)He, allows unparalleled noninvasive information on gas distribution in lung airways and distal spaces. In addition to pulmonary ventilation, lung perfusion assessment is crucial for proper diagnosis of pathological conditions, such as pulmonary embolism. Magnetic resonance perfusion imaging usually can be performed using techniques based on the detection of water protons in tissues. However, lung proton imaging is extremely difficult due to the low proton density and the magnetically inhomogeneous structure of the lung parenchyma. Here we show that laser-polarized (3)He can be used as a noninvasive probe to image, in a single MRI experiment, not only the ventilation but also the perfusion state of the lungs. Blood volume maps of the lungs were generated based on the (3)He signal depletion during the first pass of a superparamagnetic contrast agent bolus. The combined and simultaneous lung ventilation and perfusion assessments are demonstrated in normal rat lungs and are applied to an experimental animal model of pulmonary embolism. Magn Reson Med 44:1-4, 2000.

Perfusion CT and angio CT in the assessment of acute stroke

Abstract: In order to evaluate the clinical utility of non-enhanced CT with perfusion and angio CT in the assessment of acute ischaemic stroke, 42 patients with symptoms of acute stroke were examined within the first 6 h from onset of symptoms with non-enhanced CT (NECT), perfusion CT (PCT) and CT angiography (CTA). Maps of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were analysed visually, and after drawing regions of interest (ROIs) in the territory of anterior, middle and posterior cerebral arteries, maximum-intensity projection and volume-rendering images of the cervical and cerebral vessels were created. All patients underwent a control CT or MR examination 24-48 h after the initial examination. Twenty-nine patients developed an area of infarction at control examinations. Significant perfusion abnormalities were found in 27 cases, whilst in two patients the perfusion studies were considered to be normal. All the cases with perfusion abnormalities showed arterial stenoses or occlusions on angio CT. Small infarctions at levels other than the ones selected for perfusion CT, and arteriosclerotic changes, were observed in the two cases with no perfusion abnormalities. In conclusion, combining non-enhanced CT with PCT and CTA is a simple and a very valuable tool in the initial assessment of acute stroke.

Contrast ultrasound perfusion imaging of lower extremities in peripheral arterial disease: a novel diagnostic method.

Abstract: Aims The purpose of this study was to establish contrast-enhanced ultrasound perfusion imaging (CUPI) of the lower extremities as a novel non-invasive diagnostic tool for patients with peripheral arterial disease (PAD). Methods and results Ultrasound contrast agent (SonoVue™) was injected into a peripheral vein of 16 control subjects and 16 PAD patients and its appearance in the calf muscle was detected by low-energy harmonic ultrasound. Analysis of the wash-in curves revealed that PAD patients had a significantly longer time to peak intensity (TTP), i.e. duration of maximum contrast perfusion [37 s (19–79 s) in control subjects vs. 56 s (32–104 s) in PAD patients at rest, age-adjusted P =0.002]. Exercise stress test of the calf muscle resulted in a decrease of the TTP, maintaining the significant difference in TTP between the groups [19 s (8–37 s) in control subjects vs. 32 s (18–48 s) in PAD patients after exercise, age-adjusted P =0.004]. Neither ankle-brachial index and TTP nor age and TTP showed a significant correlation. Conclusion CUPI reflects the regional blood circulation of the calf muscle. In this pilot study, PAD patients show a significantly longer TTP than control subjects. The clinical relevance of CUPI is topic of ongoing studies.