Anatomy instruction by radiologists.

Ninety-four academic radiology departments responded to a questionnaire concerning anatomy instruction by radiologists. Seventy-six departments reported that radiologists teach anatomy to medical students in courses sponsored by anatomy departments (63), radiology departments (7), or both (6). The most frequent format for teaching anatomy was classroom lectures alone (25) or a combination of classroom lectures and small group instruction (24). Eighty departments indicated that additional teaching aids would be helpful.

Breast imaging. State-of-the-art.

The underlying goal of all breast imaging procedures is the detection of cancer. X-ray mammography places greatest emphasis on the disclosure of early, nonpalpable, curable cancer. Diagnostic ultrasonography stresses the differentiation of benign cysts from diagnostically indeterminate solid masses that require biopsy. Evolving experimental procedures such as transillumination light-scanning and magnetic resonance imaging currently are undergoing preliminary evaluation. An older procedure, thermography, seems to operate at a high level of effectiveness only for advanced cancer. Since x-ray mammography is the technique that has proven most successful in detecting early breast cancer, it is the standard to which all imaging alternatives must be compared.

Digital mammography. A comparison of two digitization methods.

A preliminary study of 40 different radiodense breasts digitized with a Fuji high resolution BAFBr:EU2+ imaging plate enabled us to establish acceptable enhancement procedures with a Fuji Computer Radiology 201 system. Screen-film images of 36 of these breasts were also digitized and enhanced on a Damon DETECT TV system. Three radiologists specializing in mammography reviewed each pair of images. For the 20 normal examinations, both digital methods were considered equivalent in image quality, while for the 16 cases containing pathology (masses and/or calcifications) the TV system was considered to provide the best image quality twice as often as the laser scanned system. The radiologists rejected both methods of enhancement for 8% of the images. Despite cost differences between the two systems, both have equal capability in penetrating dense breasts. However, both systems have several significant deficiencies which preclude their clinical use. At the present time, there is no objective justification for using either system for breast imaging other than in an experimental capacity.

Magnetic resonance imaging of the shoulder.

Magnetic resonance imaging is an effective means for evaluating the painful shoulder. It has been shown to display accurately pathology associated with impingement syndrome and is useful in the detection of tears of the glenoid labrum. The role of magnetic resonance imaging in evaluation of synovial pathology has not yet been defined. Additional work is needed in this area.

Delayed diagnosis of breast cancer as a result of normal mammograms.

Review of the effects of a normal mammogram on the treatment of 36 women with palpable breast carcinomas during a two-year period showed that 17 patients had biopsies performed within two months of their normal mammograms and 19 patients had biopsies delayed for three to 24 months. Of the 17 who had biopsies within one month of a normal mammogram, three (17.6%) had extension of disease to axillary nodes. Of 19 patients whose biopsy was delayed, cancer was found in axillary nodes of 11 (57.9%). Normal mammograms should not preclude biopsy of a breast mass.

Spinal neuroarthropathy after traumatic paraplegia.

Spinal neuroarthropathy is a little-known complication of traumatic paraplegia. Four cases of this syndrome are described, with emphasis on the characteristic radiographic findings of severe juxta-articular bone destruction, dense appositional new bone formation, large osteophytosis, and soft-tissue bony debris. The factors predisposing patients to develop a neuropathic joint are diminished pain and proprioceptive sensations with maintained mobility. When a paraplegic patient transfers in or out of a wheelchair or moves his upper torso, he exerts force on an insensate spine. Repeated trauma increases joint mobility beyond the normal limits, and this leads to further damage, with the process culminating in severe instability and bone destruction. The other causes of neuropathic joints in the spine--tertiary syphilis, syringomyelia, and diabetes--must be ruled out on clinical grounds. Neuropathic changes in the spine are often silent, delaying treatment, or may be mistaken for infection or degenerative disease. Their true prevalence is difficult to determine, but the possibility should be considered in paraplegic patients with the characteristic radiographic findings.

A review of mammography test objects for the calibration of resolution, contrast, and exposure.

Mandated and voluntary accreditation and quality control programs for mammography require the use of standardized mammography test objects. We evaluated eleven commercially available test objects and three prototype test objects, comparing them with respect to their resolution targets, contrast targets, and the dose they required when imaged by the same automatic exposure meter. Ion chamber and/or thermoluminescent dosimeter measurements of exposure were made with each test object, while attenuation was measured for seven. Measurements of dosage using acrylic (5 test objects) and tissue equivalent epoxy (9 test objects) showed as much as a 400% variation in the radiation supplied by the same automatic exposure device when differences in thicknesses of test objects were normalized. Speck visibility was as dependent on the composition of the specks and of the surrounding material as on the size of the specks. Contrast targets were adequate in only three test objects. Optical density differences between images of a 4-cm-thick breast and of different test object materials, also 4 cm in thickness, exposed to the same radiation, imply that untested acrylic or epoxy resin materials should not used in the calibration of automatic exposure controls.

Film-screen mammography x-ray tube anodes: molybdenum versus tungsten.

Gridless screen-film mammography at 23 kVp with a W anode (inherent filtration: 0.1 mm A1, added filtration: 0.025 mm Mo) can achieve contrast identical to that achieved with gridless film-screen mammography at 27 kVp with a Mo anode (inherent filtration: 1.0 mm Be, added filtration: 0.025-mm Mo). However, W-anode film-screen mammograms obtained at 23 kVp require more radiation than Mo-anode film-screen mammograms obtained at 27 kVp. The lack of contrast of W-anode film-screen images produced at the same kVp as Mo-anode images was verified clinically and with a low contrast test object imaged over a range of densities. A step wedge test object was then used to match contrast between Mo- and W-anode gridless film-screen images at various kVp. The low contrast test object images verified the contrast equivalence of images obtained at 23 kVp for a W anode and 27 kVp for a Mo anode. A comparison of the two kVp for different anode materials was tested clinically on ten patients. The clinical and low contrast test object experiments were reviewed by three radiologists specializing in mammography.

Focal spot size measurements with pinhole and slit for microfocus mammography units.

Many mammography units now have microfocal spots ranging in size from 0.09 to 0.4 mm for magnification radiography. On site measurements of these focal spots are not possible without invasive procedures if National Equipment Manufactures Association (NEMA) specifications are to be followed. This paper describes a method to perform such measurements expeditiously (1.5 h) and noninvasively. We describe how this method differs from NEMA test specifications, and report the test results of 22 units from ten manufacturers. Six of the focal spots were larger than the manufacturer's specifications which were based on current NEMA standards. Emphasis is placed on the need for verifiable standards for mammography x-ray systems.

Using tissue texture surrounding calcification clusters to predict benign vs malignant outcomes.

The positive predictive value of mammography is between 20% and 25% for clustered microcalcifications. For very early cancers there is often a lack of concordance between mammographic signs and pathology. This study examines the usefulness of computer texture analysis to improve the accuracy of malignant diagnosis. Texture analysis of the breast tissue surrounding microcalcifications on digitally acquired images during stereotactic biopsy is used in this study to predict malignant vs benign outcomes. 54 biopsy proven cases (36 benign, 18 malignant) are used. The texture analysis calculates statistical features from gray level co-occurrence matrices and fractal geometry for equal probability and linear quantizations of the image data. Discriminant models are generated using linear discriminant analysis and logistic discriminant analysis. Results do not differ significantly by method of quantization or discriminant analysis. Jackknife results misclassify 2 of 18 malignant cases (sensitivity 89%) and 6 of 36 benign cases (specificity 83%) for logistic discriminant analysis. From this preliminary study, texture analysis appears to show significant discriminatory power between benign and malignant tissue, which may be useful in resolving problems of discordance between pathological and mammographic findings, and may ultimately reduce the number of benign biopsies.

Establishing minimum performance standards, calibration intervals, and optimal exposure values for a whole breast digital mammography unit.

Methods are developed to establish minimum performance standards, calibration intervals, and criteria for exposure control for a whole breast digital mammography system. A prototype phantom was designed, and an automatic method programmed, to analyze CNR, resolution, and dynamic range between CCD components in the image receptor and over time. The phantom was imaged over a 5 month period and the results are analyzed to predict future performance. White field recalibration was analyzed by subtracting white fields obtained at different intervals. Exposure effects were compared by imaging the prototype phantom at different kVp, filtration (Mo vs Rh) and mAs. Calcification detection tests showed that phantom images, obtained at 28 kVp with a Mo/Mo anode/filter and low mAs technique, often could not depict Al2O3 specks 0.24 mm in diameter, while a 28 kVp Mo/Rh, higher mAs technique usually could. Stability of the system tested suggests that monthly phantom imaging may suffice. Differences in CCD performance are greater (12%) than differences in a single CCD over time (6%). White field recalibration is needed weekly because of pixel variations in sensitivity which occur if longer intervals between recalibration occur. When mean glandular dose is matched, Rh filtration gives better phantom performance at 28 kVp than Mo filtration at 26 kVp and is recommended for clinical exposures. An aluminum step wedge shows markedly increased dynamic range when exit exposure is increased by using a higher energy spectrum beam. Phantoms for digital mammography units should cover the entire image receptor, should test intersections between components of the receptor, and should be automatically analyzed.

Testing mammography equipment: evolution over a 4-year period.

The results of quality control (QC) tests on 70 mammography units in Southern California from 1986 to 1990 are reported. Thirteen facilities, selected because they housed all of the mammography units in three communities involved in a National Institutes of Health research project, had their units tested twice at an interval of 1 year. Fourteen self-selected units were also tested twice at intervals ranging from 1-3 years. Forty-three self-selected units in 31 additional facilities had testing only once. All 70 units underwent measurement of focal spot size or resolution, tube output, half-value layer (HVL), automatic exposure control (AEC) accuracy, relative kVp accuracy, mean glandular dose, and imaging of several test objects. The test results for the units tested once showed no significant differences compared to those tested twice. For the latter, once the units were tested and determined to be acceptable, retesting showed differences only in overall film optical density, dose, and AEC performance.

Mammography fixed grid versus reciprocating grid: evaluation using cadaveric breasts as test objects.

In this study we use unfixed cadaveric breasts to obtain mammography images with fixed and reciprocating grids. Sheets of acrylic, containing one or more clusters of simulated calcifications and masses, were superimposed on two fresh cadaveric breasts (3.4 and 6.5 cm thick), and were imaged with a fixed grid and a reciprocating grid. Six radiologists, working independently, attempted to identify the number of clusters and/or masses in 114 images containing 139 clusters of simulated calcifications and 42 simulated masses. Thirty-four of these images were normal, containing no lesions. For the thinner breast, no statistically significant difference was found in the detection of clusters of calcifications in the images produced with the fixed grid compared to those produced with the reciprocating grid. However, for the detection of calcifications in images of the thicker breast, sensitivity of 74% for detection of calcifications when a fixed grid was used was significantly less than sensitivity of 86% when a reciprocating grid was used (P = 0.006). The mass detection sensitivity was 91% for images made with a fixed grid compared to 96% for images made with a reciprocating grid, but the difference was not statistically significant (P = 0.346). The use of cadaveric breasts as test objects was well accepted by radiologists. Only for the thick cadaveric breast were differences between the two grids significant, and these differences were restricted to the task of finding calcifications.

Imaging of breast masses.

The American College of Radiology Breast Imaging and Reporting Data System (ACR BI-RADS) defines a mass as a space-occupying lesion seen in at least two projections. This article focuses on the management of breast masses with mammography and ultrasonography. Recommended work-up pathways are modified for nonpalpable masses, palpable masses in women over the age of 30, and palpable masses in women under the age of 30. The suggested protocols are based on scientific peer-reviewed literature whenever possible, but when evidence based studies are not available, the author relies on expert opinion.

Clinical image evaluation.

The radiologist interpreting mammograms is responsible for an ongoing evaluation of the quality of the initial images produced by the facility. The Mammography Quality Standards act requires an external review of clinical images at least every 3 years from each facility accredited. Clinical image evaluation includes an assessment of position and compression, labeling, image quality, and artifacts. For each of these assessment categories, specific criteria have been identified for distinguishing properly performed from deficient clinical images.

Mammographic analysis of calcifications.

Because mammographically detected calcifications are frequently the only sign of breast cancer, the breast radiography equipment, screen-film imaging package, and film processing should be optimized to detect such calcifications. For this purpose, dedicated units with molybdenum targets, microfocal spot magnification capability, reciprocating grids, and high output x-ray tubes are required. With the greater use of state-of-the-art mammography, intraductal carcinoma, or DCIS, manifested only by calcifications is being detected more frequently than ever. DCIS can be of the comedo, cribriform, or micropapillary types. Comedocarcinoma, characterized by linear and branching (casting) calcifications, is the most aggressive type, and it has the highest rate of recurrence after breast-conserving surgery. Cribriform and micropapillary calcifications are characteristically punctate and vary in size and shape. In addition to histologic type, the recurrence of DCIS is related to its extent at detection and whether adequate tissue was removed at the time of breast-conserving surgery. Biopsies for suspicious calcifications should be followed immediately by specimen radiography to verify their removal. If breast-conserving surgery is elected for DCIS, the resected segment of tissue should be examined with pathologic techniques designed to determine whether the margins are clear of tumor. For DCIS and invasive cancers with extensive intraductal component, microfocus magnification mammography over the surgical site is recommended prior to radiotherapy to identify any residual tumor calcifications. Although state-of-the-art mammography is very sensitive in the detection of calcifications, it is low in specificity, thus resulting in a large number of false-positive mammograms and a relatively low true-positive biopsy rate. While some benign calcifications cannot be distinguished from those of malignancy, the number of biopsies for benign conditions can be decreased by careful analysis of the mammograms in a search for features indicating benignity.

The other arthritides. Roentgenologic features of osteoarthritis, erosive osteoarthritis, ankylosing spondylitis, psoriatic arthritis, Reiter's disease, multicentric reticulohistiocytosis, and progressive systemic sclerosis.

Osteoarthritis may be divided into primary generalized and secondary forms. Primary generalized osteoarthritis is characterized by narrowing of cartilage, marginal osteophytes, and absence of erosions. The most common sites of involvement are the distal interphalangeal joints of the fingers and the first carpometacarpal joint. Secondary osteoarthritis also results in narrowing of cartilage in the absence of erosions, but in regions of mechanical stress. Erosive osteoarthritis affects predominantly the proximal and distal interphalangeal joints, and evolves into bony fusion in 12 to 15 per cent of cases, about the same percentage of interphalangeal bony fusion that occurs in psoriatic arthritis. Ankylosing spondylitis predominates in the axial skeleton where it eventually leads to fusion of the vertebrae and sacroiliac joints. Psoriatic arthritis combines many features of rheumatoid arthritis, in which synovial inflammation predominates, and ankylosing spondylitis, in which ligamentous inflammation predominates. The hands and feet are involved to an equal extent, and in 20 per cent of patients the disorder also involves the sacroiliac joints and spine. Reiter's disease, like psoriatic arthritis, differs from ankylosing spondylitis in its inconstant involvement of the spine and greater involvement of peripheral joints. Reiter's disease differs from psoriatic arthritis in its predominant involvement of the lower limbs, particularly the feet, with relative sparing of the hands and wrists. Multicentric reticulohistiocytosis is a rare disorder in which polyarthritis usually precedes the onset of nodular cutaneous eruptions, a fact that emphasizes the importance of early roentgenologic recognition. The interphalangeal joints are the predominant sites of involvement in the hands, but eventually all of the synovium lined joints become affected, with arthritis mutilans the end result in one third of cases. The erosions are strikingly symmetrical and well circumscribed, and accompanying osteoporosis is disproportionately mild. Progressive systemic sclerosis is characterized by atrophy and dystrophic calcifications in the soft tissues, ultimately leading to joint deformities and resorption of the terminal tufts of the phalanges. Resorption of bone occurs at other sites as well, and marginal erosions may develop in the metacarpophalangeal and interphalangeal joints of the hands.

Radionuclide bone imaging.

Radionuclide bone imaging of the skeleton, now well established as the most important diagnostic procedure in detecting bone metastases, is also a reliable method for the evaluation of the progression or regression of metastatic bone disease. The article concentrates on the technetium-99m agents and the value of these agents in the widespread application of low-dose radioisotope scanning in such bone diseases as metastasis, osteomyelitis, trauma, osteonecrosis, and other abnormal skeletal conditions.

Mammography screening: successes and problems in implementing widespread use in the United States.

Deterrents to the use of screening mammography include perceived risks of radiation, perceived "unnecessary" biopsies and overdiagnosis, and high cost. In addition, physicians and patients have attitudinal barriers that do not reflect objective realities. Professional and public education efforts are needed to enable women and their physicians to develop a more sophisticated understanding of the usefulness of screening mammography and the role played by the radiologist. As part of their efforts to increase the implementation of screening mammography, the American College of Radiology has developed a Mammography Accreditation Program for radiological facilities and has produced a free Mammography Resource Kit for radiologists, while the American Cancer Society has undertaken the support of local and national campaigns to establish screening programs at reduced cost. Both organizations continue to strive in partnership to increase the acceptance of screening throughout the United States.

An integrated approach to the evaluation of metastatic bone disease.

The radionuclide bone scan is the most effective whole body screening test for bone metastases. Conventional radiography, although relatively insensitive to the presence of bone metastases, is the best modality for characterizing them once they are detected in radionuclide scans. When the radionuclide bone scan and appropriate correlative radiographs are analyzed and reported together, false-positive scan findings are reduced, and scan specificity is increased. Valuable information on response to treatment may be obtained by correlating the changes seen in radiographs and radionuclide bone scans. CT or MR imaging may be useful for evaluating suspicious radionuclide bone scan findings that cannot be explained radiographically, and may influence the decision regarding the need for biopsy. CT can also be used to monitor needle-biopsy procedures. The use of CT or MR imaging is helpful in determining the local extent of metastatic disease when planning palliative surgery or radiotherapy. Although a positive diagnosis by needle biopsy is considered definitive, a negative result must be suspect and may eventually necessitate open surgical biopsy. An algorithmic approach to the workup of a possible skeletal metastasis is illustrated in Figure 12.