MRI Brain Findings in 126 Patients with COVID-19: Initial Observations from a Descriptive Literature Review.

BACKGROUND AND PURPOSE: Recently, numerous investigational studies, case series, and case reports have been published describing various MR imaging brain findings in patients with COVID-19. The purpose of this literature review was to compile and analyze brain MR imaging findings in patients with COVID-19-related illness. MATERIALS AND METHODS: Literature searches of PubMed, publicly available Internet search engines, and medical journal Web sites were performed to identify articles published before May 30, 2020 that described MR imaging brain findings in patients with COVID-19. RESULTS: Twenty-two articles were included in the analysis: 5 investigational studies, 6 case series, and 11 case reports, encompassing MR imaging of the brain in 126 patients. The articles originated from 7 different countries and were published in 14 medical journals. MR imaging brain findings included specific diagnoses (such as acute infarct, posterior reversible encephalopathy syndrome) or specific imaging features (such as cortical FLAIR signal abnormality, microhemorrhages). CONCLUSIONS: The most frequent diagnoses made on brain MR imaging in patients with COVID-19 were acute and subacute infarcts. Other common findings included a constellation of leukoencephalopathy and microhemorrhages, leptomeningeal contrast enhancement, and cortical FLAIR signal abnormality.

The negative predictive value of spiral computed tomography for the diagnosis of pulmonary embolism in patients with nondiagnostic ventilation-perfusion scans.

BACKGROUND: There is no noninvasive method to rule out pulmonary embolism when the clinical suspicion for pulmonary embolism is high. We did a prospective observational study to determine the negative predictive value of spiral computed tomography (CT) in this situation. METHODS: We performed spiral CT scans of the thorax in consecutive patients with high clinical suspicion of pulmonary embolism with intermediate or low probability ventilation-perfusion scans. Patients with negative or indeterminate spiral CT results had conventional angiography at the discretion of the attending physician. Only patients with positive spiral CT results or positive conventional angiograms were treated. All patients were observed for 6 months for evidence of venous thromboembolic disease. Clinical outcome without treatment or the results of conventional angiography were used as reference standards. False-negative results were defined as a negative spiral CT with a positive conventional angiogram or any diagnosis of venous thromboembolism within 6 months. RESULTS: Among the 103 patients who were studied, spiral CT scans were positive in 22 patients, indeterminate in 10 patients, and negative in 71 patients. Twenty-seven (26%) patients had pulmonary embolism by clinical outcome, including 3 of the 71 patients with negative spiral CT scans and 2 of the 10 patients with indeterminate scans. A negative spiral CT result had a likelihood ratio of 0.12 (95% confidence interval [CI]: 0.04 to 0.35) with a negative predictive value of 96% (95% CI: 88% to 99%). Using conventional angiography only as the reference standard, a negative spiral CT result had a likelihood ratio of 0.08 (95% CI: 0.02 to 0.31) and a negative predictive value of 93% (95% CI: 77% to 98%). CONCLUSIONS: Spiral CT has a high negative predictive value for pulmonary embolism and may replace conventional angiography in the workup of pulmonary embolism. Patients with indeterminate spiral CT results should be considered for conventional angiography.

Computed tomography and magnetic resonance imaging of patients with valvular heart disease.

Although computed tomographic (CT) and magnetic resonance (MR) evaluation of patients with valvular heart disease is almost never performed as a first line of diagnostic intervention, their performance does provide important morphologic and physiologic information concerning the etiology and the current status of the valvular dysfunction. Evaluation of chamber and great artery size as well as ventricular wall thickness provide the basis for diagnosing and analyzing severity of valvular heart disease. Furthermore, additional findings, including calcification and evidence of interstitial pulmonary edema, increase diagnostic sensitivity and confidence in diagnosis. MR examination has the advantage over CT of providing direct demonstration of the signal void jets of dysfunctional valves, as well as a means of quantitating regional and global ventricular function and severity of valvular pressure gradients.

Imaging of Mycobacterium avium-intracellulare infection in AIDS patients on highly active antiretroviral therapy: reversal syndrome.

OBJECTIVE: We recently encountered six patients with AIDS and an unusual complication of disseminated infection with Mycobacterium avium-intracellulare, which developed after the initiation of highly active antiretroviral therapy, including protease inhibitors and two new nucleoside analogues. Each patient had a febrile illness after the initiation of therapy and then developed mass lesions containing mycobacterial organisms in various organ systems, including bone, skin, and mesenteric and mediastinal nodes. All these patients suddenly experienced improvement in immunologic status as evidenced by decreasing viral loads and increasing CD4 cell counts. We chose to call this reaction "M. avium-intracellulare reversal syndrome." We describe the radiologic appearance of this unusual manifestation of infection with M. avium-intracellulare in patients with AIDS. CONCLUSION: New or enlarging lymphadenopathy or unusual musculoskeletal and cutaneous infections in patients with AIDS who are receiving highly active antiretroviral therapy may represent a response of the recovering immune system to a new or previously subclinical infection with M. avium-intracellulare.

Non-small-cell lung cancer: practice patterns of extrathoracic imaging.

RATIONALE AND OBJECTIVES: The purpose of this study was to identify practice patterns of extrathoracic imaging in patients newly diagnosed with non-small-cell lung, cancer. MATERIALS AND METHODS: The authors retrospectively reviewed the charts of 125 patients (71 men, 54 women; mean age, 67 years) from five hospitals (25 patients each) with newly diagnosed non-small-cell lung cancer. Charts were reviewed for cancer cell type, evidence of metastatic disease, and performance and results of extrathoracic imaging, including computed tomography (CT) and magnetic resonance (MR) imaging of the brain, bone scanning, and abdominal CT. RESULTS: Of 125 patients, 77 (62%) underwent extrathoracic imaging. These patients included 64 (64%) of 100 patients with clinical symptoms or laboratory signs of metastatic disease and 13 (52%) of 25 patients with no such indications. Extrathoracic imaging did not differ according to cancer cell type: It was performed for 30 (60%) of 50 patients with squamous cell carcinoma, 26 (60%) of 43 patients with adenocarcinoma, and 16 (73%) of 22 patients with non-small-cell lung cancer that was not further characterized. Brain CT or MR imaging bone scanning, or abdominal CT were performed in only 48%, 39%, and 30% of patients, respectively. Brain CT or MR images or bone scans revealed metastatic disease in seven of 20 and nine of 22 patients with clinical symptoms or laboratory signs of disease, respectively. These examinations revealed disease in four of 40 and two of 27 patients without such symptoms or signs, respectively (P < .05). No significant differences emerged among the practice patterns at the five participating hospitals. CONCLUSION: No consensus was found on performance of extrathoracic imaging in patients with newly diagnosed non-small-cell lung cancer.

Incidental lung carcinoma detected at CT in patients selected for lung volume reduction surgery to treat severe pulmonary emphysema.

PURPOSE: The authors present their experience with previously unsuspected carcinoma of the lung detected at preoperative computed tomography (CT) in patients with severe pulmonary emphysema who were scheduled to undergo lung volume reduction surgery. MATERIALS AND METHODS: Preoperative chest CT was performed in 148 patients (84 men, 64 women; mean age, 65 years +/- 8 [standard deviation]) with advanced pulmonary emphysema before lung volume reduction surgery. At surgery, an attempt was made to excise any pulmonary nodule considered suspicious for carcinoma at CT. RESULTS: Eighteen pulmonary nodules suspicious for lung cancer were found at CT in 17 (11%) of the 148 patients. Sixteen of these 148 nodules were resected at lung volume reduction surgery. Nine non-small cell carcinomas (adenocarcinoma, n = 4, including three with bronchioloalveolar differentiation; poorly differentiated, n = 3; squamous cell carcinoma, n = 2) were found in eight (5%) patients. Eight of the cancers were stage I, and one was unstaged surgically. Maximum diameters of the cancers ranged between 1.0 and 3.8 cm (median, 1.6 cm). The seven (5%) other resected nodules were all benign. CONCLUSION: A 5% rate of stage I primary lung cancer in patients selected for lung volume reduction surgery suggests that performance of chest CT in candidates for lung volume reduction surgery is appropriate not only to identify patterns of pulmonary parenchymal destruction but also to search for stage I lung cancer.

Lung volumes before and after lung volume reduction surgery: quantitative CT analysis.

The volume and severity of pulmonary emphysema in individual lungs were measured by means of quantitative computed tomography (CT) studies in 28 patients (14 women, 14 men, median age 65 yr) who underwent either bilateral (n = 15) or unilateral (n = 13) lung volume reduction surgery (LVRS). Spirometric, total body plethysmographic, and CT data (at TLC and RV) were correlated before and after LVRS. Lung volumes determined by CT correlated well with volumes obtained by total body plethysmography (p < 0.0001). For individual lungs after LVRS, CT-derived mean lung capacity decreased 13% and residual volume 20% (p < 0.00001 for each), while mean total functional lung volume (TFLV, defined as the volume of lung with CT attenuation greater than -910 Hounsfield units) increased 9% (p < 0.01), and the mean ratio of the air space to tissue space volume (V(AS)/V(TS)) decreased more at RV (23%) than at TLC (14%) (p < 0.0005 for each). In contrast, unilateral LVRS did not affect exhalation from the unoperated lung (2% reduction in RV, p = NS). The magnitude of the postoperative response (CT-derived TLC, RV, TFLV, V(AS)/V(TS)) of each operated lung was comparable for unilateral and bilateral LVRS. Thus, a lung's response to LVRS was independent from that of the contralateral lung. Moreover, postoperative alterations in TFLV and FEV1 correlated significantly (r = 0.80, p < 0.0001), which suggests that the expansion of functioning tissue may contribute to the mechanism by which LVRS palliates airway obstruction.

Increased Tc-99m MDP in multiple lumbar intervertebral disk spaces in Scheuermann disease without concomitant radiographic calcification or diskitis.

A radionuclide bone scan serendipitously revealed deposition of Tc-99m MDP in multiple lumbar intervertebral disk spaces in a 29-year-old man with extensive trauma to the left femur as a result of a motor vehicle accident. In the authors' experience, alcoholic liver disease or altered weight bearing secondary to prior trauma are not associated with intervertebral radiotracer uptake. Although it is possible that radiographically undetectable microcalcifications in the intervertebral disk spaces associated with degenerative changes, common in Scheuermann disease, account for this unusual finding, a literature search found that increased disk uptake had been reported only in two patients with Scheuermann disease who had concomitant active or healing diskitis. No other causes of increased disk uptake of Tc-99m MDP were found.