Patrick M. Vos

Computer-aided detection of pulmonary embolism on CT angiography: Initial experience

Objective To evaluate the performance of a computer-aided detection (CAD) system for diagnosis of pulmonary embolism on computed tomography (CT) pulmonary angiography. Materials and Methods One hundred and four pulmonary CT angiograms for pulmonary emboli (PE) were reviewed both by radiologists and a CAD detection system (ImageChecker CT V2.0, R2 Technology Inc, Sunnyvale, CA). CT scans, read and reported by radiologists in a routine daily clinical setting, were later processed by the CAD system. The performance of the CAD system was analyzed. Results Forty-five PE were identified by the radiologists in 15 patients. The CAD system revealed 123 findings, interpreted by the system as PE. Twenty-six of them, detected in 8 patients, represented true-positive results. Ninety-seven (78.9%) CAD findings were not true PE and were defined as false-positive. Nineteen true PE in 7 patients were missed by the CAD system constituting 42% false-negative rate. Sensitivity of the CAD system was 53.3% and the specificity was 77.5%. The positive predictive value of CAD system was 28.5% and the negative predictive value was 90.7%. Conclusions With the evaluated CAD system, it is relatively simple and fast to check all detected findings and decide if they represent true PE. However, high false-negative results demand technologic improvement, to increase the sensitivity of the system. It is anticipated to become a promising supplement to the work and eyes of the radiologist in detecting PE on pulmonary CT angiography.

Evaluation of MRI for the Diagnosis of Appendicitis During Pregnancy When Ultrasound is Inconclusive

BACKGROUND To retrospectively evaluate the diagnostic performance and clinical utility of magnetic resonance imaging (MRI) in pregnant patients suspected of having acute appendicitis, when an ultrasound study generated an inconclusive result. METHODS The medical records of 19 consecutive women who underwent abdominal and pelvic MRI at a tertiary care referral center (St. Pauls Hospital, Vancouver, Canada), as part of the work up of clinically suspected acute appendicitis, were retrospectively reviewed. MRI was carried out when ultrasound findings were inconclusive. MRI findings were reviewed and compared with surgical findings and clinical follow-up data including pregnancy outcome. RESULTS One of the 19 patients (5.3%) in the study cohort had an appendicitis diagnosed by MRI that was confirmed at operation and by specimen histology. The remaining study patients were diagnosed as not having appendicitis by MRI. These patients were followed until delivery, which was uneventful for all but one patient who was found to have appendicitis during Cesarean section. Overall, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MRI for the diagnosis of appendicitis during pregnancy was 50.0%, 100%, 100%, 94.4%, and 94.7%, respectively. In three patients (16.7%) with no MRI evidence of appendicitis, MRI identified an alternative etiology for their abdominal pain (two patients diagnosed with ovarian cysts, one patient diagnosed with a uterine fibroid). CONCLUSIONS MRI represents a useful diagnostic test for acute appendicitis in pregnant women, and decreases the need for an emergency operation. Its high negative predictive value makes MRI useful for ruling out appendicitis in pregnant patients who have an inconclusive ultrasound. However, the low sensitivity observed in this study suggests that MRI, like other imaging modalities, is not perfect, and may miss an acute appendicitis diagnosis. Thus, future prospective clinical study of MRI as a diagnostic test for the evaluation of women who present with acute abdominal pain and possible appendicitis during pregnancy is warranted.

Chest Radiographic and CT Manifestations of Chronic Granulomatous Disease in Adults

OBJECTIVE The purpose of this study was to describe the thoracic radiologic findings of chronic granulomatous disease in adults. MATERIALS AND METHODS We retrospectively analyzed the chest radiographic and CT findings in four adults with chronic granulomatous disease during five episodes of lower respiratory tract infection. RESULTS Chest radiographic findings included areas of consolidation (60%), diffuse reticulonodular opacities (40%), pleural effusion (20%), and pulmonary artery enlargement (20%). CT findings included areas of consolidation (60%), pulmonary nodules in a random distribution (60%), centrilobular nodules (60%), tree-in-bud opacities (40%), areas of scarring and traction bronchiectasis (100%), emphysematous changes (75%), areas of decreased attenuation and vascularity associated with air trapping on expiratory CT (50%), mediastinal and/or hilar lymphadenopathy (60%), pulmonary artery enlargement (50%), and pleural effusion (20%). Areas of consolidation and nodules were the most prominent findings and at histologic examination were found to be associated with infection or granulomatous inflammation. CONCLUSION The pulmonary radiologic findings of chronic granulomatous disease include consolidation, nodules, areas of scarring, traction bronchiectasis, emphysema, air trapping, mediastinal and hilar lymphadenopathy, pulmonary artery enlargement, and pleural effusion.

Incidental littoral cell angioma of the spleen

BackgroundLittoral cell angioma (LCA) is a recently described primary vascular neoplasm of the spleen that may be associated with other malignancies and may itself also have malignant potential.Case presentationWe present a case of LCA that was discovered incidentally in a 52-year-old woman who presented with biliary colic at the time of consultation for cholecystectomy. This vascular neoplasm was evaluated by ultrasound, CT, MRI, Tc-99m labelled red blood cell scintigraphy, and core biopsy. A splenectomy revealed LCA by pathological evaluation. Post-operative outcome was favourable with no evidence of complication or recurrent disease. Following this case presentation, clinical, radiographic, and pathological features of LCA will be reviewed as well as recent advances in our understanding of this uncommon splenic lesion.ConclusionLCA is a rare, generally benign, primary vascular tumour of the spleen that typically is discovered incidentally. Individuals diagnosed with this tumour must be carefully evaluated to exclude primary, secondary, and synchronous malignancies.

T2 mapping of articular cartilage of glenohumeral joint with routine MRI correlation--initial experience.

The evaluation of articular cartilage currently relies primarily on the identification of morphological alterations of the articular cartilage. Unlike anatomic imaging, T2 mapping is sensitive to changes in the chemical composition and structure of the cartilage. Clinical evaluation of T2 mapping of the glenohumeral joint has not been previously reported. The objectives of this study were to evaluate the feasibility of magnetic resonance T2 mapping of the glenohumeral joint in routine clinical imaging, to assess the normal T2 mapping appearance of the glenohumeral joint, and to compare the findings on T2 maps to conventional MR pulse sequences. Magnetic resonance imaging (MRI) examinations of 27 shoulders were performed in a routine clinical setting. All studies included acquisition of T2 mapping using a dedicated software. The T2 maps were analyzed along with the routine MR exam and correlation of cartilage appearance on T2 map and on conventional MR sequences. T2 imaging maps were obtained successfully in all patients. T2 maps and routine MRI correlated in cases of normal cartilage and prolonged T2 values and cartilage defects. In four cases, increased T2 relaxation times in the cartilage and cartilage defects were more apparent on T2 maps. Acquisition of T2 maps at the time of routine MRI scanning is feasible and not time-consuming.

Is it a fibroid? Are you sure? Sonography with MRI assistance.

Uterine fibroids are common benign lesions. Other common benign masses include renal cysts, renal angiomyolipomas, hepatic cysts, hepatic hemangiomas, thyroid cysts, adrenal incidentalomas, pulmonary granulomas and hamartomas, ovarian cysts, and dermoids. All these conditions, especially in asymptomatic patients, almost never have clinical significance. However, it is important to differentiate them from more sinister or even malignant lesions. In general, when a lesion is described as a fibroid, no further evaluation is performed. So if we say that a lesion is a fibroid, we have to be sure. Endometrial fibroids may mimic endometrial polyps or endometrial cancer. Subserous, especially pedunculated fibroids, may need further evaluation to differentiate them from ovarian pathology, colonic pathology, or even müllerian duct anomalies. Pelvic magnetic resonance imaging may be helpful in these cases.

How to Measure Scapholunate and Cobb’s Angles on MRI and CT

The measurement of angles between anatomical structures is common in radiological and orthopedic practice. Frequently used measurements include scapholunate angle for assessment of wrist instability and Cobb’s angle used for assessment of scoliosis. Measurements of these angles are easily performed on plain X-ray radiographs. However, the situation is more complicated when these measurements are to be performed on cross-sectional (CT or MRI) examinations. On some of the diagnostic workstations, it is not possible to perform angle measurements between the structures if they are not identified on the same image and are located on different images of the same projection or plane. We present a simple solution to measure angles between structures on different images that can be used both in CT and MR.

Do we really need to thank the Beatles for the financing of the development of the computed tomography scanner

Abstract It is commonly believed that the revenues from the selling of the Beatles’ records by Electric and Musical Industries (EMI) allowed the company to develop the computed tomography (CT) scanner. Some went to define this as the Beatles’ gift to medicine. However, significant controversies and discrepancies arise from analysis of this statement, making its correctness doubtful. The details of financing required for the CT development and the part of EMI in financial input have never been publicly announced. This work analyzes the financial contributions to the CT development and investigates if the revenues received from the sales of the Beatles’ records were used for the creation of the CT scanner. Timeline of the development of the EMI CT scanner and the financial inputs of EMI and British Department of Health and Social Security (DHSS) were assessed. Without salary expenses to Godfrey Hounsfield and his team, the development of the CT scanner cost EMI approximately £100,000. The British DHSS’s expenses were £606,000. Hence, the financial contribution of DHSS into the development of the CT scanner was significantly bigger than that of EMI. Accordingly, British tax payers and officials of British DHSS are to be thanked for the CT scanner. The Beatles’ input into the world’s culture is valuable and does not require decoration by nonexistent connection to the development of CT. A positive aspect to this misconception is that it keeps in public memory the name of the company that developed the CT scanner.

Radiologic Signs of Weapons and Munitions: How Will Noncombatants Recognize Them?

OBJECTIVE The purpose of this work was to show the radiologic signs named after weapons and munitions along with their military counterparts to help radiologists recognize these signs, which will allow confident interpretation and diagnosis. CONCLUSION Numerous pathologic conditions have classic radiologic manifestations that resemble weapons and ammunition. Most of these signs are highly memorable and easy to recognize. However, the names of the weapons (some of them antique and some not commonly known) may confuse radiologists who are not familiar with the appearance of such weapons as the scimitar, bayonet, or dagger. The value of the signs is reduced if the radiologist is unfamiliar with the appearance of the corresponding weapon.

Dual-energy computed tomography: a promising novel preoperative localization study for treatment of primary hyperparathyroidism

BACKGROUND The objective of this study was to evaluate dual-energy computed tomography (DE-CT) for preoperative parathyroid tumor (PT) localization in individuals undergoing parathyroidectomy for treatment of primary hyperparathyroidism (PHP). METHODS DE-CT was evaluated by retrospective review of the clinical and biochemical characteristics, imaging, operative findings, and outcomes for PHP cases undergoing an initial operation at a single center. RESULTS The accuracy of each preoperative imaging test, based on operative findings and pathological confirmation of removal of a PT from the localized site was: 58% for ultrasound, 75% Tc-99m sestamibi noncontrast single photon emission noncontrast CT, and 75% for DE-CT. DE-CT was able to correctly localize a PT in a 3rd of cases that were nonlocalized. All study patients had normalization of serum calcium and parathyroid hormone levels postoperatively. CONCLUSIONS DE-CT shows promise for the preoperative PT localization, especially in nonlocalized PHP cases, and warrants further investigation.