Radiography Imaging Techniques

Semioblique lateral view. The central beam is centred on the web space between the thumb and the index finger Semi oblique lateral view (radial deviated, thumb abducted lateral view) : here the patient's wrist is in maximal radial deviation and thumb in maximum abduction. The forearm is kept 45° supination [ Figure ]. This view reveals a fracture of hook of Hamate.

Electron-probe X-ray fluorescence (EP-XRF) analysis has been widely used in scanning electron microscopy instrumentation for elemental analysis of specimens. In the SEM, the surface of a solid sample is excited with a highly-focused energetic beam of electrons, which induces X-ray fluorescence from the elements within the sample. Polycapillary collimating optics can be used to direct emitted X-ray fluorescence as a parallel beam from the small electron excitation area to a flat crystal monochrometer to increase the diffracted beam intensity and therefore greatly increase the elemental discrimination and detection sensitivity.

X-ray diffraction relies on the dual wave/particle nature of X-rays to obtain information about the structure of crystalline materials. A primary use of the technique is the identification and characterization of compounds based on their diffraction pattern. The dominant effect that occurs when an incident beam of monochromatic X-rays interacts with a target material is scattering of those X-rays from atoms within the target material. In materials with regular structure (i.e. crystalline), the scattered X-rays undergo constructive and destructive interference. This is the process of diffraction. The diffraction of X-rays by crystals is described by Bragg’s Law, nλ=2d sinΘ. The directions of possible diffractions depend on the size and shape of the unit cell of the material. The intensities of the diffracted waves depend on the kind and arrangement of atoms in the crystal structure. However, most materials are not single crystals, but are composed of many tiny crystallites in all pos...

Perfusion is the delivery of blood through the arterial system and capillaries to the tissue and it can be calculated by various techniques with different units. In large vessels, blood flow is measured as a velocity, but in the capillary bed perfusion is calculated as the volume of blood delivered to a volume of tissue at a given time (mL/min/100 mL) [5]. CT Perfusion requires administration of iodine contrast and dynamic image acquisition covering the structures of interest. In the absence of image artifacts, there is a linear correlation between the measured x-ray attenuation and the iodine concentration, which makes the mathematical modeling straightforward. By subtracting the initial unenhanced image, it is possible to create tissue attenuation curves voxel by voxel. It is important to take into consideration that iodine contrast is not a strict intravascular agent, so the enhancement represents both intravascular contrast and contrast in the extracellular space.

The most common means of screening for colon cancer is conventional colonoscopy, which involves threading a fiberoptic scope into the large bowel. This procedure is typically performed under sedation, requiring a recovery period. The bowel lining is directly visualized with a tiny optical camera. If polyps are found, they can be removed at the time of the procedure. The procedure has been considered the “gold standard” for colon cancer screening for a number of years. It is highly accurate and quite safe. The patient must thoroughly cleanse their bowel prior to the examination. This is called a bowel “prep.” There is a low incidence of complications associated with colonoscopy, including perforation of the colon wall. This is a rare occurrence, but can have serious consequences when it occurs. CT colonoscopy (virtual colonoscopy) is a new technique for inspecting the wall of the colon. It is still under investigation and is not yet considered to be a standard screening test. Early ...

A combination of MRI and ultrasound is able to measure the metabolism rates of cancer cells, according to research on a new technique developed by researchers at Tel Aviv University. The MRI-ultrasound technique has been refined for breast cancer identification so that each course of treatment is as individual as the woman being treated. The approach helps determine at an earlier stage than ever before which cells are metastasizing, and how they should be treated. The MRI-and-ultrasound-imaging application monitors the metabolic changes that occur during cancer metastasis. Increased blood flow (which can be sensed by ultrasound) and an increase of oxygen consumption (measured with an MRI) can indicate cancer metastasis with unprecedented levels of sensitivity. Normally scientists look for structural changes in the body, such as the presence of a tumor. But with their new methods, clinicains are able to “see” cancer metastasis within a small group of cells long before the cancer...

DIA’s vision is that each women receives informed and  experienced care,  with the purpose  of better health and  quality-of-life.Breast MRI is not to replace mammography, which has saved many lives from breast cancer. Instead it provides a powerful supplementary tool for detecting and staging breast cancer. The two tests are both great exams, each with their own strengths. Most commonly, Breast MRI is performed to answer a specific question raised from the patient’s mammogram. Breast MRI is a more sensitive test in detecting breast cancer than mammography. There are some cancers that can be seen with MRI that cannot be seen with mammography. This is especially true in patients who have dense breast tissue. Regardless of breast density, if a breast cancer is present, Breast MRI can detect it greater than 95% of the time, while mammography can detect cancer approximately 80-90% of the time. If the patient has dense breast tissue, the rate of detection of cancer can g...

evaluate abnormalities detected by mammography. identify early breast cancer not detected through other means, especially in women with dense breast tissue and those at high risk for the disease. screen for cancer in women who have implants or scar tissue that might jeopardize an accurate result from a mammogram. determine the integrity of breast implants. distinguish between scar tissue and recurrent tumors. assess multiple tumor locations. check the progress of chemotherapy. look for multiple tumors prior to breast conservation surgery. determine whether cancer detected by mammography or ultrasound has spread further in the breast or into the chest wall. determine how much cancer has spread beyond the surgical site after a breast biopsy or lumpectomy. provide additional information on a diseased breast to make treatment decisions.

Mammography, also known as a mammogram, is the examination of the breasts using x-rays. Mammography is considered the most effective tool for early breast tumor detection. Most medical experts agree that successful treatment of breast cancer often is linked to early diagnosis. There are two types of mammography, screening and diagnostic. Screening mammography is used for patients with no symptons or concerns. Two standard images are taken of each breast. Diagnostic mammography is a specialized mammogram designed to solve a particular problem. The radiologist designs each exam in order to answer the particular problem at hand. Our practice uses digital mammography. Also known as a full-field digital mammography, digital mammography produces images that are shown on a high resolution monitor. Because the images are digital, they allow the radiologist to alter the magnification, brightness and contrast of the images to produce detailed images . Computer-aided detection, or CAD, uses...

Check the sydesmotic integrity. The distal tibia and fibula are held together by the syndesmotic ligaments. On the AP view, the overlap of the tibia and fibula is measured. If this distance is less than 10mm, it suggests injury to the sydesmotic ligaments.

Shocking: Robbers plunged this five inch blade into a 15-year-old boy's head The muggers responded by using a kitchen knife to stab one of the boys in the forehead, another twice in the back and a third in the shoulder. Horrific: Amazingly the teenager survived this knife attack and has now enrolled in college

Chest lobes in X-ray anatomy , radio graphic anatomy of the chest lobes in x ray chest 

Contrast-Induced Nephropathy Contrast-induced nephropathy refers to a reduction in renal function after the administration of an ICA. The standard diagnostic criteria for contrast-induced nephropathy is a greater than 25% increase in baseline serum creatinine concentration within 3 days of receiving an ICA after other possible causes have been ruled out. Serum creatinine will usually peak within 3 to 7 days and return to baseline (or a new baseline) within 14 days. In many patients, the course is usually benign; however, the development of contrast-induced nephropathy can prolong hospital stay, increases the need for dialysis, and increases overall mortality.50, 51 The major risk factors for contrast-induced nephropathy can be found in Table 2. Preexisting renal dysfunction is the greatest risk factor for developing contrast-induced nephropathy, and the risk becomes greater with increasing baseline renal impairment. The incidence of contrast-induced nephropathy is less than 5% in p...

Delayed reactions to contrast agents are those that occur at least 1 hour after but within 1 week of receiving an ICA. Typical delayed reactions can manifest with signs and symptoms similar to an acute reaction, such as rash, pruritus, nausea, vomiting, diarrhea, and, occasionally, hypotension; however, reactions with cutaneous manifestations are most common. These cutaneous manifestations can be diverse in nature but typically occur as a pruritic maculopapular rash or urticaria.40 Severe skin reactions, such as toxic epidermal necrolysis and Stevens-Johnson syndrome, have also been reported.41, 42 Delayed reactions tend to be milder in nature than acute reactions. The overall incidence of delayed reactions after the administration of an ICA can be as high as 14%.40 Iso-osmolar agents (ie, nonionic dimers) are associated with the highest risk of causing a delayed reaction. Specifically, the incidence of a delayed cutaneous reaction after a nonionic dimer is 3 times greater than after ...

Extravasation can occur during hand or power injection in 0.1%–0.9% of cases but is more common in the latter. The elderly, infants, children, patients with altered consciousness, and those with underlying vascular disease are more prone to extravasation. Small extravasations of contrast media usually produce a local inflammatory response in the skin, without serious sequela. Larger volumes (50–75 mL) may produce tissue damage from chemotoxicity or resultant compartment syndrome (19,20). Patients usually present with persistent burning and swelling at the injection site. Assessment of the patient's pulse distal to the injection site and documentation of initial swelling and erythema are essential in early management. Smaller extravasations may be managed with elevation and cold compresses. In cases with persistent swelling, pain, and discoloration, it is best to consult a surgeon. Complications of contrast extravasation tend to be more severe with higher-osmolality contrast agen...

All the currently used contrast media are chemical modifications of a 2,4,6-triiodinated benzene ring. They are classified on the basis of their physical and chemical characteristics, including their chemical structure, osmolality, iodine content, and ionization in solution (2,3). The parent molecule from which the contrast agents are derived is benzene. This is a toxic water-insoluble liquid. The carbon atoms on a benzene ring are numbered clockwise from 1 to 6. Benzoic acid is produced by introducing an acid group at position 1 on the benzene ring. This acid group permits the formation of salts or amides, which influence water solubility. 2,4,6-triiodobenzoic acid is obtained by introducing iodine atoms at positions 2, 4, and 6 on the ring. Iodine is the element used in contrast media as it possesses 3 important properties essential for the production of contrast media: high-contrast density, firm binding to the benzene molecule, and low toxicity. Triiodobenzoic acid is made less...

The exact causal mechanism of contrast-induced anaphylactic reactions is still debated. From his extensive research, Elliot Lasser1 has proposed a mechanism in which the large contrast-containing molecule causes an overload effect on the antigen-binding sites on immunoglobulin E (IgE) of mast cells and basophils and does not bind directly to an antigen-specific site. This effect varies with the particular contrast medium. Since the immuno-globulin binding is nonspecific, the resultant reaction depends on the quantity of circulating IgE and mast cells at the time the contrast medium is administered. This nonspecific binding helps explain why patients with strong allergic history are at particular risk and why prior exposure to the contrast agent is not necessary for a reaction to occur. Other considerations are that direct contact of the contrast agent with the endothelium of blood vessels may activate Factor XII;this substance in turn activates kallikrein; kallikrein activates bradyk...

Skin testing and RAST (radioallergosorbent test) have not been helpful in the diagnosis of contrast media allergy. Small “test” doses are also not helpful, with reports of severe, life-threatening reactions occurring even at such amounts. Severe reactions to larger doses of contrast media have been observed after a person tolerated a small dose of IV dye. Therefore, the diagnosis of contrast media allergy is made only after symptoms have occurred. Otherwise, it is only possible to determine that a person is at increased risk of a reaction to contrast media based on the risk factors outlined below.6 Allergy Prevention and Treatment As mentioned above, the purpose of using these contrast agents is for diagnosis, but like any medical procedure in any radiological study, the right dose or volume of contrast media needs to be determined prior to a procedure. The total volume or dose is dependent upon several factors: iodine concentration of the contrast media; type of injectable cont...

Both high-osmolar contrast media (ionic) and low-osmolar contrast media (nonionic or organic) agents contain iodine and are administered intravenously. Most intravascular contrast media are derivatives of tri-iodobenzoic acid. The iodine molecule is an effective x-ray absorber in the energy range where most clinical systems operate. Iodinated contrast media are the most efficient products to enhance the visibility of vascular structures and organs during radiographic procedures. The ionic type creates more charged particles and causes a high osmolality in blood, which may cause a potentially life-threatening contrast media reaction in some individuals with medical conditions. The nonionic agents generate less dissociation and particles and decrease this risk, but are much more expensive. The nonionic contrast media are much more widely used today. The iodine concentration of contrast media is determined by the number of iodine molecules in milligrams present in a milliliter of a solu...

Nephrogenic systemic fibrosis (NSF),  a serious, debilitating, and sometimes fatal scleroderma-like disorder,  is associated with the administration of intravenous gadolinium. The primary risk factor is renal failure (patient on dialysis or with a GFR < 30).   The guidelines for administration of gadolinium are as follows: Gadolinium should be avoided or minimized in patients with known renal failure (eGFR<30ml/min) or renal insufficiency (eGFR<90ml/min). If enhanced MR is deemed necessary by the radiologist, the exam will be performed after informed consent, with single-dose Multihance or other alternative to Omniscan (gadodiamide). Omniscan (gadodiamide) should be avoided in patients with any amount of renal insufficiency. Single-dose Multihance or other gadolinium contrast agent will be used in place of Omniscan (gadodiamide) for enhanced MR studies in patients with any known renal insufficiency (eGFR<90 ml/min). Patients with an eGFR>90ml/min...

Patients on dialysis can receive IV contrast, and early post-procedural dialysis is not routinely required; however, the fact that a patient is on dialysis should not be regarded as automatically allowing the administration IV contrast.  The administration of contrast may jeopardize the return of renal function in patients who are receiving dialysis for acute renal failure and may further worsen renal function in patients who still make some urine but receive dialysis intermittently.  The volume of iv contrast should also be considered in patients on dialysis who are at risk for volume overload.

Estimated glomerular filtration rate is a better predicator of renal dysfunction than creatinine alone.  The decision to proceed with contrast administration in patients with an estimated GFR < 45 ml/min/1.732 is a matter of clinical judgment, based on the individual circumstances of the patient and following consultation between the radiologist and requesting physician.   Strategies to prevent nephropathy in patients with renal impairment include hydration, reduction of contrast dose, and discontinuation of nephrotoxic drugs. A critical diagnostic study should not be delayed because of excessive concern regarding possible contrast nephropathy.

Prednisone 50mg po at 13 hours, 7 hours and 1 hour prior to planned administration of intravenous contrast plus diphenhydramine 50mg po, iv or im at 1 hour prior to planned administration of intravenous contrast Or Methylprednisolone 32mg po at 12 hours and 2 hours prior to planned administration of contrast plus diphenhydramine 50 mg po, iv or im at 1 hour prior to the planned administration of contrast Or Hydrocortisone 200mg iv at 13 hours, 7 hours and 1 hour prior to planned administration of intravenous contrast if patient is unable to take po medications

TYPE AGENTS High osmolality Ionic Diatrizxoate sodium (Hypaque) Iothalamate meglumine (Conray) Low osmolality Ionic Ioxaglate meglumine (Hexabrix) Nonionic Gadodiamide (Omniscan) Gadoteoridol (ProHance) Iodixanol (Visipaque) Iopamidol (Isovue) Iopromide (Ultravist) Ioversol (Optiray)

Reference: Acta Radiologica (2007) Iodinated Contrast Gadolinium Contrast The risk of a severe allergic reaction occurring 1:100,000 of people having iodinated contrast Less than 1:170,000 of people having gadolinium contrast. The risk of renal failure  if eGFR <30 ml/min): 20-40% will get contrast induced nephropathy (CIN) 5% will experience permanent decrease in renal function No risk The risk of NSF if eGFR < 15ml/min): No risk 5% The risk of a missed diagnosis if contrast medium is not used: If CT scanning is inferior to MRI for the particular symptom or disease, the consequences of a missed diagnosis from the scanning procedure needs to be taken into consideration as a risk If MRI is inferior to CT scanning for the particular symptom or disease, the consequences of a missed diagnosis from the scanning procedure needs to be taken into consideration as a risk. The effect of a patient receiving dialysis soon after gadolinium contrast...

There is an increased risk of this condition occurring in patients with an already reduced kidney function. The risk is increased if a patient has large amounts of iodine containing contrast medium or multiple procedures using iodine containing contrast medium over a short period of time, i.e. hours to a few days. It can result in temporary, prolonged or permanent worsening of kidney function which could result in the need for temporary or permanent dialysis in the most severely affected patients. There is a clinical prediction rule available to estimate the probability of contrast induced nephropathy in a patient, based on risk factors. PLEASE NOTE: If you have a kidney problem the radiologist is very likely to completely avoid using gadolinium or iodine if a diagnosis can be confirmed using another test or by performing a CT or MRI without gadolinium or iodine.

Nephrogenic Systemic Fibrosis (NSF) (also known as Nephrogenic Fibrosing Dermopathy) This condition is rare and, so far, has occurred  only  in people with severe kidney disease. No cases were reported prior to 1997. It causes swelling and tightening of the skin of the extremities and less often the trunk. It develops over days to weeks and may reduce movement of the joints. It can also cause damage to internal organs in rare cases. About 5% of people with the most severe level of kidney function reduction will get NSF after a gadolinium injection and less than 5% of these people (or 3 in every 10,000 people with severely reduced kidney function)) will die of it. NSF is much more common with some gadolinium contrast agents than others and is more common after multiple doses of gadolinium based contrast media. Improvements in kidney function, through kidney transplant or other measures, have been shown in some cases to result in remission of NSF but this is not always th...