Pulmonary and aortic blood flow measurements in normal subjects and patients after single lung transplantation at 0.5 T using velocity encoded cine MRI.

PURPOSE: It is the purpose of this study to compare pulmonary and aortic blood flow measurements obtained in patients after single lung transplantation (SLTX) with those in volunteers. METHODS/MATERIAL: In nine patients after SLTX (three male, six female) and nine volunteers (seven male, two female), double oblique phase contrast cine-MRI sequences perpendicular to the direction of blood flow were obtained in the ascending aorta, main, right, and left pulmonary artery on a 0.5-T unit (Philips Gyroscan; Best, the Netherlands) (repetition time, 600 to 800 ms; echo time, 8 ms; alpha=30; field of view=280 mm matrix, 128x256, ECG gating, temporal resolution 16 time frames/RR interval). An initial in vitro study using the same sequence on a nonpulsatile flow phantom showed excellent correlation (r=0.99) between MRI measurements of flow velocity and flow volume and true velocity and flow volume. Measurements of blood flow volume (mL/min), peak mean systolic velocity, resistive index, and distensibility index were obtained in each vessel. RESULTS: We found excellent correlations between left and right cardiac output as measured by velocity encoded cine-MRI (VEC-MRI) in the ascending aorta and main pulmonary artery both in normal volunteers (r=0.95) and in patients (r=0.91). Differential pulmonary blood flow measurements in volunteers showed that 55% of the right cardiac output was directed to the right and 45% to the left lung. Differential pulmonary blood flow in patients showed that most of the blood flow (81%) reaches the transplanted lung and only 19% reaches the patient's own lung (SLTX: 4.5+/-1.8 L/min, patient's own lung: 1.2+/-0.8 L/min). There were significant differences (p<0.05) in peak mean systolic velocity and resistive index obtained in the pulmonary arteries, both between normal volunteers and patients and between measurements obtained in the patient's own lung and the transplanted lung. CONCLUSION: VEC-MRI blood flow measurements are a promising noninvasive tool to monitor the hemodynamic changes of pulmonary blood flow after SLTX.

The postoperative spine.

During the last decade, magnetic resonance imaging (MRI) mostly has replaced computed tomography for evaluation of spinal surgery patients. The inherent advantages of MRI are obvious for this particularly difficult field of imaging. With MRI, it is possible to demonstrate anatomic as well as pathological and iatrogenic changes in three different imaging planes and countless neighboring planes and to obtain a superior view of the complex postoperative situation regardless of the spinal level imaged. Soft-tissue masses in particular can be identified more readily and located within three-dimensional space. One of the major advantages is that the nature and histology of the mass can be estimated precisely using different MR sequences in combination with intravenous contrast media. The most important benefit may be demonstration of inflammatory and hemorrhagic masses in the early postoperative periods (with special emphasis on alterations visible in the spinal cord itself) as well as repair processes and ongoing degeneration in later stages. This visualization is possible even when their extent is limited. In the postoperative spine, the application of MRI was facilitated with the advent of new materials, such as titanium alloys, used for surgical instrumentation. These new materials limit the amount of artifacts visible on MR images. Earlier implants made of other metallic material prohibit the use of computed tomography in the spine. This article provides a brief overview of the progress in spinal surgery and focuses on the developments in MRI techniques during the last decade. Technical questions about imaging of spinal instrumentation are discussed. "Normal" postoperative findings needed for interpretation of pathologic conditions are also discussed. Finally, the most important frequently asked questions from referring surgeons that radiologists must be able to answer by MRI are presented.

CT and MR assessment of osteoporosis.

Over the past decades there has been remarkable progress in the development and application of non-invasive radiological methods for assessing the skeletal bone mass and status. It is possible to evaluate the peripheral or axial entire skeleton as well as the trabecular bone or cortical bone envelopes with a high degree of accuracy and precision, and with a reasonable capacity for determining bone strength and predicting fracture risk. Cross sectional imaging methods such as CT and MR yield significant advantages for these applications since they are the only techniques which allow for accurate three dimensional localization of tissue and for true isolation of the trabecular and the cortical bone compartment. Both methods can be applied to practically every anatomic location in the human body.

Overuse edema in the bone marrow of the hand: demonstration with MRI.

In MRI of the skeleton, marrow edema is a frequent finding that can be caused by avascular necrosis, fracture, bone bruises, transient osteoporosis, osteomyelitis, primary tumors, metastases, and altered biomechanical properties. We examined a 29-year-old woman golfer with mild pain and swelling of the proximal phalanx II of the left hand. No signs of a stress fracture were seen on the MR images or plain radiographs. MRI revealed increased signal intensity on T2-weighted images in the metacarpal and proximal phalanx II in the left hand. We concluded that bone marrow edema may be the result of physiologic bone response to stress and may not necessarily correspond with severe trauma. Our case complements recent observations outlining the influence of altered biomechanics as a reason for marrow edema.

[Clinical application of densitometry]. / Die klinische Anwendung der Densitometrie.

An early diagnosis of osteoporosis and an accurate estimation of treatment outcome are the focus of the radiological efforts. The most commonly applied methods for the evaluation of the peripheral and axial skeleton are dual x-ray absorptiometry, quantitative computed tomography, and quantitative ultrasound. Data of an individual are generally compared to an age-, sex-, and ethically-matched control population. The bone mass measurement predict a patients future risk of fracture and the presence of osteoporosis can be diagnosed even in the absence of prevalent fractures. Fracture risk increases approximately 1.5-2.5 times for every 1.0 standard deviation an individual's bone mass is below the mean peak mass of healthy young individuals (T-score). The choice of the appropriate measurement sites may vary depending on the specific circumstances of the patient. The choice of the appropriate technique in any given clinical circumstance should be based on the strength and limitations of the different techniques.

[Bone densitometry: comparative value and limitations of different techniques]. / Osteodensitometrie: Signifikanz und Limitationen im methodischen Vergleich.

An early diagnosis of osteoporosis and an accurate estimation of treatment outcome are the focus of the radiological efforts. The most commonly applied methods for the evaluation of the peripheral and axial skeleton are dual x-ray absorptiometry, quantitative computed tomography, and quantitative ultrasound. Data of an individual are generally compared to an age-, sex-, and ethically-matched control population. The bone mass measurement predicts a patient's future risk of fracture and the presence of osteoporosis can be diagnosed even in the absence of prevalent fractures. Fracture risk increases approximately 1.5-2.5 times for every 1.0 standard deviation an individual's bone mass is below the mean peak bone mass of healthy young individuals (T-score). The choice of the appropriate measurement sites may vary depending on the specific circumstances of the patient. The choice of the appropriate technique in any given clinical circumstance should be based on the strength and limitations of the different techniques.

[Computed tomography and magnetic resonance imaging of acquired abnormalities of the inner ear and cerebello-pontine angle]. / CT und MRT erworbener Veränderungen des Innenohrs und Kleinhirnbrückenwinkels.

CT and MRI of acquired abnormalities of the inner ear and cerebello-pontine angle present themselves with very typical findings. The imaging should be adapted to the pathology looked for and either CT or MRI should be used alone or in combination. CT, especially high resolution CT (HRCT), provides an excellent bone contrast, while MRI has a much superior soft tissue contrast. Acute inflammatory changes of the inner ear are solely depicted by contrast-enhanced MRI. HRCT excellently depicts osseous changes of the inner ear and cerebellopontine angle such as chronic ossifying labyrinthitis occurring after acute labyrinthitis, otosclerotic or traumatic changes. Tumorous changes not yielding to bony changes are best delineated by MRI. Posttraumatic hemorrhage and chronic fibrotic changes within the labyrinth are depicted by MRI, only. In conclusion HRCT and MRI are excellent methods to delineate acquired abnormalities of the inner ear and cerebello-pontine angle. HRCT best depicts osseous changes while MRI best depicts soft tissue changes. HRCT and MRI are not concurrent methods but should better be used as complementary methods for imaging acquired abnormalities of inner ear and cerebellopontine angle.

[CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontine angle]. / CT und MRT tumoröser Veränderungen des Schläfenbeins.

Tumours lesions of the temporal bone and of the cerebello-pontine angle are rare. This tumours can be separated into benign and malignant lesions. In this paper the CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontane angle will be demonstrated. High resolution CT (HRCT) as usually performed in the axial plane are using a high resolution bone window level setting, coronal planes are the reconstructed from the axial data set or will be obtained directly. With the MRI FLAIR sequence in the axial plane the whole brain will be scanned either to depict or exclude a tumour invasion into the brain. After this,T2-weighted fast spin echo sequences or fat suppressed inversion recovery sequences in high resolution technique in the axial plane will be obtained from the temporal bone and axial T1-weighted spin echo sequences before and after the intravenous application of contrast material will be obtained of this region. Finally T1-weighted spin echo sequences in high resolution technique with fat suppression after the intravenous application of contrast material will be performed in the coronal plane. HRCT and MRI are both used to depict the most exact tumorous borders. HRCT excellently depicts the osseous changes for example exostosis of the external auditory canal, while also with HRCT osseous changes maybe characterized into more benign or malignant types. MRI has a very high soft tissue contrast and may therefore either characterize vascular space-occupying lesions for example glomus jugulare tumours or may differentiate between more benign or malignant lesions. In conclusion HRCT and MRI of the temporal bone are excellent methods to depict and mostly characterize tumour lesions and can help to differentiate between benign and malignant lesion. These imaging methods shall be used complementary and may have a great impact for the therapeutic planning.

Scimitar syndrome: MR assessment of hemodynamic significance.

We report a case of anomalous pulmonary venous drainage into the inferior vena cava (scimitar syndrome) in which the hemodynamic significance was noninvasively assessed by means of velocity-encoded cine MR. Left-to-right shunt was calculated from direct blood flow measurements performed in the ascending aorta, main pulmonary artery, and aberrant pulmonary vein.

[Calcium in the lung or: it might not always be tuberculosis]. / Der Kalk in der Lunge oder: Es muss nicht immer die Tuberkulose sein.

Pulmonary calcifications are a frequent finding in CT examinations of the chest. In many cases, characteristic CT morphology and distribution of pulmonary and mediastinal calcifications may lead to a straightforward specific diagnosis of the underlying disease. In that respect, calcifications are often the residual finding of previous infections. Less often, they may be due to neoplasms, metabolic disorders, occupational exposure or previous therapy. This review focuses on the etiology, pathogenesis and morphological CT features of pulmonary calcifications. A knowledge of the technical aspects of CT imaging is required to verify calcifications and avoid pitfalls.

Rheumatoid arthritis of the craniocervical region: assessment and characterization of inflammatory soft tissue proliferations with unenhanced and contrast-enhanced CT.

The aim of this study was to depict and characterize inflammatory soft tissue proliferations caused by rheumatoid arthritis (RA) in the craniocervical region by unenhanced and contrast-enhanced CT. Computed tomography of the craniocervical region was performed in 35 patients in the axial plane before and after the i.v. administration of contrast material. According to the densities and contrast enhancement of the inflammatory soft tissue proliferations, four groups were classified. Ancillary findings, such as a compression of the dural sac or spinal cord, erosions of the bony structures, and atlantoaxial subluxation, were also evaluated. Inflammatory soft tissue proliferations were depicted in 28 of 35 patients and could be differentiated by unenhanced and contrast-enhanced CT according to the above defined criteria: effusion in 6 patients (17%); hypervascular pannus in 8 (23%); hypovascular pannus in 5 (14%); and fibrous tissue in 9 patients (26%). A compression of the dural sac was seen in 11 (31%) patients; 3 of these had neurological symptoms. Erosions of the odontoid process were found in 20 (57%) patients; 16 (80%) of these also showed erosions of the atlas. Atlantoaxial subluxation was seen in 11 (31%) patients. Inflammatory soft tissue proliferations in the craniocervical region caused by RA can be reliably demonstrated and classified by unenhanced and contrast-enhanced CT, which can differentiate between joint effusion and various forms of pannus and depict ancillary findings. Computed tomography is an alternative method for patients unable to undergo an MRI examination.

[Pulmonary hypertension and cor pulmonale]. / Pulmonale Hypertension und Cor pulmonale.

Pulmonary hypertension is a severe disorder of the pulmonary circulation and occurs in a variety of vascular and parenchymal lung diseases. It leads to volume and/or pressure overload of the right ventricle and finally to right heart failure. Pulmonary vascular diseases such as chronic pulmonary embolism cause a drastic increase in pulmonary vascular resistance, which results in extremely high pulmonary artery pressures that can even reach systemic levels. On the other hand, moderate pulmonary hypertension can also occur in chronic obstructive and restrictive lung diseases. For a long time, the diagnosis of pulmonary hypertension and cor pulmonale was based upon findings in echocardiography and right heart catheterization. Today modern imaging techniques allow the radiologist to assess right ventricular and pulmonary artery morphology and function. The application of spiral CT, electron-beam CT and MRT permits the diagnosis and differential diagnosis of pulmonary hypertension and also the evaluation and follow-up of underlying vascular or parenchymal lung disorders. In addition, quantification of right ventricular function and calculation of pulmonary hemodynamic parameters are possible.

Comparison of imaging-guided and non-imaging-guided quantitative sonography of the calcaneus with dual X-ray absorptiometry of the spine and femur.

OBJECTIVE: The purpose of our study was to evaluate the diagnostic agreement between imaging-guided and non-imaging-guided quantitative sonography of the calcaneus and dual X-ray absorptiometry of the spine and femur to show osteoporosis. SUBJECTS AND METHODS: In 113 patients (73 women, 59 +/- 14 years old; 40 men, 48 +/- 16 years old), dual X-ray absorptiometry of the lumbar spine and the proximal femur, imaging-guided quantitative sonography, and non-imaging-guided quantitative sonography of the calcaneus were performed. The percentage of patients having a T-score equal to or less than a threshold of -2.5 SDs (prevalence of osteoporosis) was calculated for each imaging technique. The diagnostic agreement of the three techniques in identifying individuals with osteoporosis was assessed. RESULTS: Eleven percent of the women and 8% of the men were classified as osteoporotic by imaging-guided quantitative sonography, and 38% of the women and 25% of the men were so classified by non-imaging-guided quantitative sonography. At dual X-ray absorptiometry of the spine, 44% of the women and 38% of the men were classified as osteoporotic, and, at different femoral regions, 19-60% of the women and 8-38% of the men were so classified. Kappa analysis for both quantitative sonography techniques was not significant. Kappa analysis for both quantitative sonography techniques and dual X-ray absorptiometry showed diagnostic agreement to be generally poor. CONCLUSION: No advantage in diagnostic accuracy could be found for imaging-guided quantitative sonography. The considerable diagnostic disagreement between both quantitative sonography techniques and dual X-ray absorptiometry could be confusing in daily clinical practice.

Weil disease: importance of imaging findings for early diagnosis.

Weil disease is a rare and severe outcome of infection with leptospires. We report the radiographic appearance of this disease in a patient with hepatic, renal, and pulmonary involvement. Imaging findings added significantly to an early correct diagnosis and, thus, to immediate and successful therapy in this critically ill patient.

[Ewing sarcoma. Diagnostic imaging]. / Das Ewing-Sarkom. Bildgebende Diagnostik.

Ewing's sarcoma is a highly malignant neoplasm of the bone whose origin is still uncertain. A strong relationship exists between Ewing's sarcoma and tumors of neural origin (Ewing family of tumors). Ewing's sarcoma must be distinguished from other round-cell tumors like lymphoma and neuroblastoma and also must be differentiated from osteogenic sarcomas. On plain radiographs, Ewing's sarcoma appears as a lytic or mixed lytic-sclerotic, rarely as predominantly sclerotic lesion with margins Lodwick grade III. It is located primarily in the diaphyseal and metadiaphyseal regions of the long bones of the lower extremities. A large soft tissue tumor is usually present. Magnetic resonance imaging is the imaging modality of choice to evaluate the extent of the primary lesion, to monitor the response to neoadjuvant chemotherapy and to follow up non-resected Ewing's sarcomas. Bone scintigraphy is necessary to detect skeletal metastasis, and 201thallium scanning has been shown to be sensitive in the monitoring of treatment response. Today, computed tomography is not longer used to image the tumor site; however, spiral CT of the lungs plays a central role as a staging and follow-up tool.

Diagnostic disagreement of imaging quantitative sonography of the calcaneus with dual X-ray absorptiometry of the spine and femur.

OBJECTIVE: This study evaluates the diagnostic agreement between imaging quantitative sonography of the calcaneus and dual X-ray absorptiometry of the spine and femur for diagnosing osteoporosis. MATERIALS AND METHODS: In 498 female patients (56 +/- 18 years old), bone mineral density measurements by dual X-ray absorptiometry of the lumbar spine (posteroanterior, L1--L4) and the proximal femur and imaging quantitative sonography of the calcaneus were performed. The percentage of patients having T-scores less than or equal to a threshold of -2.5 standard deviations below a young normal reference was used to compare quantitative sonography with dual X-ray absorptiometry. The diagnostic agreement was assessed using kappa scores. RESULTS: Approximately 30% of the patients had a T-score less than or equal to -2.5 standard deviations as assessed by imaging quantitative sonography (broadband ultrasound attenuation), 26.5% as assessed by dual X-ray absorptiometry of the spine, and 16.7--56.4% as assessed by dual X-ray absorptiometry of the different regions of interest at the femur. Kappa analysis showed that severe diagnostic disagreement exists among broadband ultrasound attenuation and dual X-ray absorptiometry (kappa = 0.28-0.42). CONCLUSION: Considerable diagnostic disagreement exists between imaging quantitative sonography and dual X-ray absorptiometry of the spine and femur. The disagreement is in the same range as that reported recently in comparisons of dual X-ray absorptiometry and nonimaging quantitative sonography. In general, no distinct advantage for imaging quantitative sonography could be found when compared with other techniques.

Spiral CT of the lung in children with malignant extra-thoracic tumors: distribution of benign vs malignant pulmonary nodules.

The purpose of this paper is to clarify the distribution of benign vs malignant pulmonary nodules which are seen on spiral CT in children with malignant extra-thoracic solid tumors. Seventy-four children with known solid, extra-thoracic tumors underwent spiral CT of the chest. According to the initial and follow-up (interval 9.2+/-4.7 months) findings, the children were graded into four groups: I = normal; II = solitary nodule unchanged at follow-up; III = multiple nodules with one or more than one unchanged at follow-up; and IV = solitary or multiple nodules all changed at follow-up. Nodules without change at follow-up were regarded as benign. Forty-nine children did present with normal pulmonary CT exams. In 7 cases solitary pulmonary nodules were found unchanged (group II) at follow-up and in 2 cases (group III) some of the nodules were stationary. Thus, 12% (9 of 74) presented with at least one pulmonary nodule that did not change at follow-up. Solitary nodules (in groups II and IV) with a diameter <5 mm were in 70 % (7 of 10) unchanged at follow-up and regarded as benign. In children with known solid extra-thoracic tumors at initial presentation, 70% of solitary nodules ( <5 mm) may be benign. To avoid overstaging, smaller solitary nodules must not automatically be regarded as metastases.

Diagnostic agreement of quantitative sonography of the calcaneus with dual X-ray absorptiometry of the spine and femur.

OBJECTIVE: The aim of our study was to evaluate the diagnostic agreement between quantitative sonography of the calcaneus and dual X-ray absorptiometry (DXA) of the spine and femur for revealing osteoporosis. SUBJECTS AND METHODS: In 1252 patients (795 women, 54.9+/-15 years old; 457 men, 50.5+/-15 years old [mean+/-SD]), bone mineral density measurements of the lumbar spine (posteroanterior, L1-L4) and the proximal femur (neck, trochanter, intertrochanteric region, total proximal femur, and Ward's triangle) and quantitative sonographic measurements of the stiffness of the calcaneus were performed. The presence of osteoporosis is defined, according to the World Health Organization criteria, as a T-score lower than -2.5. The percentage of patients below the threshold (prevalence of osteoporosis) was calculated for each imaging technique. The diagnostic agreement in identifying individuals as osteoporotic was assessed using kappa scores. RESULTS: Forty-nine percent of the women and 42% of the men were classified as osteoporotic by quantitative sonography, 32% of women and 30% of men by DXA of the spine, and 23-54% of women and 16-54% of men by the different regions of interest revealed on femoral DXA. Kappa analysis showed the diagnostic agreement among these measures to be generally poor (kappa = .28-.41 [women] and .25-.45 [men]). CONCLUSION: The considerable diagnostic disagreement between quantitative sonography and DXA could cause confusion in the daily practice of radiology and make establishing the correct diagnosis a difficult task. The choice of imaging technique influences which patients are diagnosed as osteoporotic.