Castleman Disease Presenting with Pseudotumour Cerebri and Myasthenia Gravis: A Case Report and Literature Review.

Castleman disease (CD) is a rare lymphoproliferative disorder that may present with various autoimmune, inflammatory, or neurologic syndromes. This is a case of a 21-year-old woman who presented with signs and symptoms of pseudotumour cerebri (PTC) who subsequently developed myasthenia gravis (MG), and was incidentally found to have a large mass in the posterior mediastinum. Upon resection, the mass was classified as unicentric CD involved with follicular dendritic cell sarcoma. Following treatment with IVIG in the setting of progressive weakness and dyspnea, she has had complete symptom resolution while maintained on a low dose of pyridostigmine for the last two years. There are 13 cases of MG and five cases of optic disc edema described as PTC associated with CD in the literature, but to our knowledge, this is the sole case reported of the intersection of all three conditions in one patient. Increased serum levels of interleukin-6 and vascular endothelial growth factor may provide clues as to the association of CD with these neurologic syndromes.

Clinical utility of quantitative imaging.

Quantitative imaging (QI) is increasingly applied in modern radiology practice, assisting in the clinical assessment of many patients and providing a source of biomarkers for a spectrum of diseases. QI is commonly used to inform patient diagnosis or prognosis, determine the choice of therapy, or monitor therapy response. Because most radiologists will likely implement some QI tools to meet the patient care needs of their referring clinicians, it is important for all radiologists to become familiar with the strengths and limitations of QI. The Association of University Radiologists Radiology Research Alliance Quantitative Imaging Task Force has explored the clinical application of QI and summarizes its work in this review. We provide an overview of the clinical use of QI by discussing QI tools that are currently used in clinical practice, clinical applications of these tools, approaches to reporting of QI, and challenges to implementing QI. It is hoped that these insights will help radiologists recognize the tangible benefits of QI to their patients, their referring clinicians, and their own radiology practice.

Methods and challenges in quantitative imaging biomarker development.

Academic radiology is poised to play an important role in the development and implementation of quantitative imaging (QI) tools. This article, drafted by the Association of University Radiologists Radiology Research Alliance Quantitative Imaging Task Force, reviews current issues in QI biomarker research. We discuss motivations for advancing QI, define key terms, present a framework for QI biomarker research, and outline challenges in QI biomarker development. We conclude by describing where QI research and development is currently taking place and discussing the paramount role of academic radiology in this rapidly evolving field.

Complications from computed tomography-guided core needle biopsy for patients receiving stereotactic body radiation therapy for early-stage lesions of the lung.

BACKGROUND: Obtaining a tissue diagnosis has traditionally been standard practice before initiating therapy for early-stage non-small-cell lung cancer (NSCLC). In several recent studies from Europe and Asia, a substantial proportion of patients have received stereotactic body radiation therapy (SBRT) based only on the imaging characteristics of the suspicious lesion. The underlying assumption is that the risk of percutaneous needle biopsy may outweigh the benefits in a population that generally has underlying pulmonary dysfunction and other medical comorbidity. Nevertheless, there is limited information regarding biopsy-related complication rates in high-risk patients with early-stage NSCLC who are treated with SBRT. MATERIALS AND METHODS: This was a retrospective review of outcomes after biopsy in patients treated with SBRT. Complications of percutaneous core needle biopsy were analyzed in relation to patient and tumor characteristics. Each biopsy event was analyzed independently for patients with multiple biopsies. RESULTS: A total of 112 percutaneous biopsies were performed in 103 patients. Pneumothorax of any degree was observed in 40 patients (35%) (95% CI, 27%-45%), and 12 patients (10.7%) had a clinically significant pneumothorax requiring chest tube placement (95% CI, 6%-18%). The time to first fraction of SBRT was not different in patients who had a pneumothorax or placement of a chest tube. On multivariate analysis, age, performance status, smoking history, pack-years of smoking, chronic obstructive pulmonary disease history, and forced expiratory volume in the first second of expiration were not statistically significantly associated with chest tube placement. CONCLUSION: Computed tomography-guided needle biopsy in a primarily medically inoperable patient population is safe, with an acceptable degree of complications.

Measurement of cardiac output from dynamic pulmonary circulation time CT.

PURPOSE: To introduce a method of estimating cardiac output from the dynamic pulmonary circulation time CT that is primarily used to determine the optimal time window of CT pulmonary angiography (CTPA). METHODS: Dynamic pulmonary circulation time CT series, acquired for eight patients, were retrospectively analyzed. The dynamic CT series was acquired, prior to the main CTPA, in cine mode (1 frame/s) for a single slice at the level of the main pulmonary artery covering the cross sections of ascending aorta (AA) and descending aorta (DA) during the infusion of iodinated contrast. The time series of contrast changes obtained for DA, which is the downstream of AA, was assumed to be related to the time series for AA by the convolution with a delay function. The delay time constant in the delay function, representing the average time interval between the cross sections of AA and DA, was determined by least square error fitting between the convoluted AA time series and the DA time series. The cardiac output was then calculated by dividing the volume of the aortic arch between the cross sections of AA and DA (estimated from the single slice CT image) by the average time interval, and multiplying the result by a correction factor. RESULTS: The mean cardiac output value for the six patients was 5.11 (l/min) (with a standard deviation of 1.57 l/min), which is in good agreement with the literature value; the data for the other two patients were too noisy for processing. CONCLUSIONS: The dynamic single-slice pulmonary circulation time CT series also can be used to estimate cardiac output.

A case of hut lung: scanning electron microscopy with energy dispersive x-ray spectroscopy analysis of a domestically acquired form of pneumoconiosis.

Hut lung is a pneumoconiosis caused by exposure to smoke derived from biomass fuels used for cooking in poorly ventilated huts. We report, to our knowledge, the first analysis of the dust deposited in the lungs in hut lung by scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDS). A Bhutanese woman presented with shortness of breath and an abnormal chest radiograph. Chest CT scan showed innumerable tiny bilateral upper lobe centrilobular nodules. Transbronchial biopsy revealed mild interstitial fibrosis with heavy interstitial deposition of black dust. SEM/EDS showed that the dust was carbonaceous, with smaller yet substantial numbers of silica and silicate particles. Additional history revealed use of a wood/coal-fueled stove in a small, poorly ventilated hut for 45 years. The possibility of hut lung should be considered in women from countries where use of biomass-fueled stoves for cooking is common. Our findings support the classification of this condition as a mixed-dust pneumoconiosis.

KERMA ratios in pediatric CT dosimetry.

BACKGROUND: Patient organ doses may be estimated from CTDI values. More accurate estimates may be obtained by measuring KERMA (Kinetic Energy Released in Matter) in anthropomorphic phantoms and referencing these values to free-in-air X-ray intensity. OBJECTIVE: To measure KERMA ratios (R(K)) in pediatric phantoms at CT. MATERIALS & METHODS: CT scans produce an air KERMA K in a phantom and an air KERMA K(CT) at isocenter. KERMA ratios (R(K)) are defined as (K/K(CT)), measured using TLD chips in phantoms representing newborns to 10-year-olds. RESULTS: R(K) in the newborn is approximately constant. For the other phantoms, there is a peak R(K) value in the neck. The median R(K) values for the GE scanner at 120 kV were 0.92, 0.83, 0.77 and 0.76 for newborns, 1-year-olds, 5-year-olds and 10-year-olds, respectively. Organ R(K) values were 0.91 ± 0.04, 0.84 ± 0.07, 0.74 ± 0.09 and 0.72 ± 0.10 in newborns, 1-year-olds, 5-year-olds and 10-year-olds, respectively. At 120 kV, a Siemens Sensation 16 scanner had R(K) values 5% higher than those of the GE LightSpeed Ultra. CONCLUSION: KERMA ratios may be combined with air KERMA measurements at the isocenter to estimate organ doses in pediatric CT patients.

In-patient to isocenter KERMA ratios in CT.

PURPOSE: To estimate in-patient KERMA for specific organs in computed tomography (CT) scanning using ratios to isocenter free-in-air KERMA obtained using a Rando phantom. METHOD: A CT scan of an anthropomorphic phantom results in an air KERMA K at a selected phantom location and air kerma K(CT) at the CT scanner isocenter when the scan is repeated in the absence of the phantom. The authors define the KERMA ratio (R(K)) as K∕ K(CT), which were experimentally determined in a Male Rando Phantom using lithium fluoride chips (TLD-100). R(K) values were obtained for a total of 400 individual point locations, as well as for 25 individual organs of interest in CT dosimetry. CT examinations of Rando were performed on a GE LightSpeed Ultra scanner operated at 80 kV, 120 kV, and 140 kV, as well as a Siemens Sensation 16 operated at 120 kV. RESULTS: At 120 kV, median R(K) values for the GE and Siemens scanners were 0.60 and 0.64, respectively. The 10th percentile R(K) values ranged from 0.34 at 80 kV to 0.54 at 140 kV, and the 90th percentile R(K) values ranged from 0.64 at 80 kV to 0.78 at 140 kV. The average R(K) for the 25 Rando organs at 120 kV was 0.61 ± 0.08. Average R(K) values in the head, chest, and abdomen showed little variation. Relative to R(K) values in the head, chest, and abdomen obtained at 120 kV, R(K) values were about 12% lower in the pelvis and about 58% higher in the cervical spine region. Average R(K) values were about 6% higher on the Siemens Sensation 16 scanner than the GE LightSpeed Ultra. Reducing the x-ray tube voltage from 120 kV to 80 kV resulted in an average reduction in R(K) value of 34%, whereas increasing the x-ray tube voltage to 140 kV increased the average R(K) value by 9%. CONCLUSIONS: In-patient to isocenter relative KERMA values in Rando phantom can be used to estimate organ doses in similar sized adults undergoing CT examinations from easily measured air KERMA values at the isocenter (free in air). Conversion from in-patient air KERMA values to tissue dose would require the use of energy-appropriate conversion factors.

Diagnosis of pulmonary Langerhans cell histiocytosis by CT-guided core biopsy of lung: a report of three cases.

A pathological diagnosis of pulmonary Langerhans cell histiocytosis (PLCH) usually requires a surgical lung biopsy. To date, diagnosis of PLCH by core needle biopsy has not been reported. Three cases are presented of PLCH diagnosed by CT-guided core biopsy in adult female smokers found to have multiple small bilateral lung nodules. The nodules biopsied were 5 mm, 7 mm and 1 cm in size, and showed interstitial expansion by Langerhans cells and eosinophils. CT-guided core biopsy should be considered as one of the less invasive techniques by which a pathological diagnosis of PLCH can be established.

Treatment advances for medically inoperable non-small-cell lung cancer: emphasis on prospective trials.

Advances in technology have changed the treatment of patients with early stage non-small-cell lung cancer who are not healthy enough for standard surgical resection. Previously, patients with severe underlying cardiopulmonary dysfunction were often dissuaded from pursuing definitive therapy, even though most patients died from their lung cancer and not as a result of comorbid medical illness. Recent advances in the technology to treat early stage disease have led to new-found enthusiasm for treating and studying high-risk patients. This Review focuses on the management of these patients, including use of conformal radiotherapy, stereotactic body radiation therapy, sublobar resection, intraoperative brachytherapy, and radiofrequency ablation. Ongoing challenges are presented and prospective data are emphasised.

Definitive treatment of poor-risk patients with stage I lung cancer: a single institution experience.

PURPOSE: Lung cancer remains the leading cause of cancer death in both men and women. A substantial number of patients with early stage non-small cell lung cancer (NSCLC) are unfit for standard surgery due to cardiopulmonary dysfunction and/or other comorbidity. The appropriate management for this population has not been defined. METHODS: Retrospective analysis of patients with clinical stage I NSCLC judged to be unsuitable for lobectomy between 1996 and 2005. RESULTS: Ninety-six patients, representing 23% of all patients treated for clinical stage I NSCLC were included in this analysis. The median age was 73 years and most patients were female. Patients underwent limited resection (LR, n = 45), primary radiotherapy (RT, n = 39) or radiofrequency ablation (n = 12). With median follow-up of 30 months, 61 patients remain alive. Actuarial 3-year survival is 65% following LR and 60% after primary RT. Local tumor relapse and distant metastases were observed with approximate equal probability following either LR or RT. CONCLUSION: Medical inoperability does not necessarily correspond to poor survival in patients with early stage NSCLC. A nihilistic approach is not warranted towards this population, and prospective trials are needed to better define optimal treatment strategies.

A method to obtain mean organ doses in a RANDO phantom.

A quantitative method of obtaining average organ dose from point measurements made in the male RANDO phantom is described for 24 compact organs of interest in patient dosimetry. A three-dimensional Cartesian coordinate system was created by considering each of the 36 RANDO phantom sections as the z coordinate, and using a rectangular frame to assign x and y coordinates relative to the center of each section. Anatomical atlases and clinical experience were used to identify the location and extent of each organ and tissue in the RANDO phantom. This proposed scheme is comparable to one used in a commercial phantom and offers investigators a comprehensive protocol for obtaining mean organ doses in the RANDO phantom.

Thyroid involvement with Langerhans cell histiocytosis in a 3-year-old male.

We report on the thyroid involvement with Langerhans cell histiocytosis (LCH) in a 3-year-old male. The patient presented with goiter and primary hypothyroidism. His goiter caused life-threatening airway obstruction. He developed locally invasive disease 4 years after his response to LCH therapy. LCH should be suspected as a cause of goiter and thyroidectomy is recommended.

How do lesion size and random noise affect detection performance in digital mammography?

RATIONALE AND OBJECTIVES: We investigated the effect of random noise and lesion size on detection performance in mammography. MATERIALS AND METHODS: Digital mammograms were obtained of an anthropomorphic breast phantom with and without simulated mass lesions. Digital versions of the mass lesions, ranging in size from 0.8 to 12 mm, were added back to the breast phantom image. Four alternate forced choice experiments were performed to determine the lesion contrast required to achieve a 92% correct lesion detection rate, denoted I92. Experiments were performed using identical phantom images and different versions of phantom images obtained using the same techniques but with different random noise patterns. RESULTS: For lesions larger than 1 mm, the slope of the contrast detail curves was always positive. This behavior contrasts with conventional contrast-detail curves in uniform backgrounds in which the slope is approximately -0.5. There was no difference between twinned experiments and those obtained using different patterns of random noise for lesions greater than 1 mm. When the lesion size was reduced below 1 mm, the detection threshold increased indicating a deterioration of lesion detectability, and detection performance was significantly lower when random noise patterns were used. CONCLUSION: Our results suggest that lesion detection is dominated by anatomical structure for lesions with a size >1 mm, but by random noise for submillimeter sized lesions.

Protective pneumothorax for needle biopsy of mediastinum and pulmonary hilum.

The risk of performing CT-guided transthoracic needle biopsy of some mediastinal and pulmonary hilar masses is increased by the presence of intervening lung. A series of patients is presented in whom a protective pneumothorax provided access for biopsy of masses in the mediastinum and pulmonary hilum. Review of Interventional Radiology records revealed 24 patients who had biopsies of mediastinum or pulmonary hilum, in whom protective pneumothorax was used, or attempted, to provide percutaneous access for biopsy. Characteristics of these patients and their procedures were reviewed. Percutaneous access to the pleural space was gained in 21/24 (88%) of patients. A protective pneumothorax was established in 19 (79%); 2 patients had pleural adhesions that prevented the lung from being displaced. The process of creating the protective pneumothorax added a mean time of 17 minutes to the procedure (range 6-30 minutes). All patients had biopsy using coaxial technique, with either a 20-gauge or 18-gauge core biopsy instrument, in addition to needle aspiration. Air leak requiring tube drainage occurred in 1/19 (5%) of patients who had a protective pneumothorax, and in 2/5 (40%) of patients in whom protective pneumothorax was not established. Percutaneous creation of a protective pneumothorax is a safe method that provides access for needle biopsy of deep lesions in the chest without traversing aerated lung.

Performance of a single lookup table (LUT) for displaying chest CT images.

RATIONALE AND OBJECTIVES: To evaluate the ability to view mediastinal and lung information on one window setting by processing images with a bilinear lookup table (LUT). MATERIALS AND METHODS: Chest computed tomography (CT) studies were obtained from 32 consecutive adult patient studies, which included 7 iodine contrast studies. From each CT examination, four sections were selected containing the suprasternal notch, carina, right inferior pulmonary vein, and the dome of the lower hemidiaphragm. Each image was processed with a bilinear LUT in addition to the lung setting (window width 1500 and window level -500) and mediastinal setting (window width 450 and window level 50) normally used. Seven radiologists compared the quality of the bilinear LUT with the corresponding lung and mediastinum display settings. A five-point scale was used to assess image quality, with a score of 5 being equivalent to the corresponding lung (or mediastinum) display, 3 being acceptable, and 1 being unacceptable. RESULTS: The average score of the bilinear LUT for all images and readers was 3.90 +/- 0.93 for lung information and 3.17 +/- 1.00 for mediastinum information. Use of the bilinear LUT resulted in unacceptable images in 0.3% cases for lung information and 5.9% for mediastinum information. Chest CT images that contained iodinated contrast resulted in a higher score than those obtained without contrast, but these differences did not achieve statistical significance. CONCLUSION: Use of a bilinear LUT has the potential to significantly improve operational efficiency with acceptable image quality for most chest CT images.

Patient size and x-ray transmission in body CT.

Physical characteristics were obtained for 196 patients undergoing chest and abdomen computed tomography (CT) examinations. Computed tomography sections for these patients having no evident pathology were analyzed to determine patient dimensions (AP and lateral), together with the average attenuation coefficient. Patient weights ranged from approximately 3 kg to about 120 kg. For chest CT, the mean Hounsfield unit (HU) fell from about -120 HU for newborns to about -300 HU for adults. For abdominal CT, the mean HU for children and normal-sized adults was about 20 HU, but decreased to below -50 HU for adults weighing more than 100 kg. The effective photon energy and percent energy fluence transmitted through a given patient size and composition was calculated for representative x-ray spectra at 80, 100, 120, and 140 kV tube potentials. A 70-kg adult scanned at 120 kVp transmits 2.6% of the energy fluence for chest and 0.7% for abdomen CT examinations. Reducing the patient size to 10 kg increases transmission by an order of magnitude. For 70 kg patients, effective energies in body CT range from approximately 50 keV at 80 kVp to approximately 67 keV at 140 kVp; increasing patient size from 10 to 120 kg resulted in an increase in effective photon energy of approximately 4 keV. The x-ray transmission data and effective photon energy data can be used to determine CT image noise and image contrast, respectively, and information on patient size and composition can be used to determine patient doses.

Use of the VIP-Man model to calculate energy imparted and effective dose for x-ray examinations.

A male human tomographic model was used to calculate values of energy imparted (epsilon) and effective dose (E) for monoenergetic photons (30-150 keV) in radiographic examinations. Energy deposition in the organs and tissues of the human phantom were obtained using Monte Carlo simulations. Values of E/epsilon were obtained for three common projections [anterior-posterior (AP), posterior-anterior (PA), and lateral (LAT)] of the head, cervical spine, chest, and abdomen, respectively. For head radiographs, all three projections yielded similar E/epsilon values. At 30 keV, the value of E/epsilon was approximately 1.6 mSv J(-1), which is increased to approximately 7 mSv J(-1) for 150 keV photons. The AP cervical spine was the only projection investigated where the value of E/epsilon decreased with increasing photon energy. Above 70 keV, cervical spine E/epsilon values showed little energy dependence and ranged between approximately 8.5 mSv J(-1) for PA projections and approximately 17 mSv J(-1) for AP projections. The values of E/epsilon for AP chest examinations showed very little variation with photon energy, and had values of approximately 23 mSv J(-1). Values of E/epsilon for PA and LAT chest projections were substantially lower than the AP projections and increased with increasing photon energy. For abdominal radiographs, differences between the PA and LAT projections were very small. All abdomen projections showed an increase in the E/epsilon ratio with increasing photon energy, and reached a maximum value of approximately 13.5 mSv J(-1) for AP projections, and approximately 9.5 mSv J(-1) for PA/lateral projections. These monoenergetic E/epsilon values can generate values of E/epsilon for any x-ray spectrum, and can be used to convert values of energy imparted into effective dose for patients undergoing common head and body radiological examinations.

How good is the ACR accreditation phantom for assessing image quality in digital mammography?

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the American College of Radiology (ACR) accreditation phantom for assessing image quality in digital mammography. MATERIALS AND METHODS: Digital images were obtained of an ACR accreditation phantom at varying mAs (constant kVp) and varying kVp (constant mAs). The average glandular dose for a breast with 50% glandularity was determined for each technique factor. Images were displayed on a 5 mega-pixel monitor, with the window width and level settings individually optimized for viewing the fibers, specks, and masses in the ACR phantom. Digital images of the ACR phantom were presented in a random manner to eight observers, each of whom indicated the number of objects visible in each image. RESULTS: Intraobserver variability was greater than interobserver variability for the detection of fibers and specks, but the reverse was true for the detection of masses. As the mAs increased, the number of fibers visible increased from less than one at 5 mAs to all six being visible at 80 mAs. The corresponding number of visible specks increased from 12 to 24, and the number of visible masses increased from 1.25 to about four. Above 26 kVp, object visibility was constant with increasing x-ray tube voltage. Reducing the x-ray tube voltage to 24 kVp, however, reduced the number of visible fibers from six to five, the number of visible specks from 24 to 21.1, and the number of visible masses from four to 3.1. Observer performance was approximately constant for average glandular doses greater than 1.6 mGy, so that the range of lesion detectability in the ACR phantom occurs at doses lower than those normally encountered in clinical practice. CONCLUSION: The current design of the ACR phantom is unsatisfactory for assessing image quality in digital mammography.

How do radiographic techniques affect image quality and patient doses in CT?

The radiation dose received by patients who undergo CT examinations has become a subject of considerable interest. Adult effective doses for head CT examinations are of the order of 1 to 2 mSv, and for single body examinations, patient doses are typically between 4 and 6 mSv. These doses are high in comparison to most other types of radiological examinations that use ionizing radiation. Patient CT doses may also be compared with natural background (3 mSv/year), dose limits to members of the public (1 mSv/year), and the highest level of occupational exposure, which is about 5 mSv/year. The advent of multi-slice technology will serve to increase CT utilization, as well as individual doses for any given examination. Radiologists are responsible for medical radiation doses to their patients, and it is imperative that they understand the relationship between radiation dose and image quality. In this review, we address the impact that variations in radiographic techniques (ie, selected values of X-ray kVp and mAs) have on patient doses as well as the quality of the resultant CT images.