Crescent Sign Research Articles

Abdominal aortic aneurysm: rupture associated with the high-attenuating crescent sign.

To determine the histopathologic features of the ruptured abdominal aortic aneurysm associated with the high-attenuating crescent sign on computed tomographic (CT) scans and to suggest a possible mechanism for the rupture. Histopathologic examination was performed with specimens from six patients with a ruptured aneurysm associated with the high-attenuating crescent sign and from eight patients with a nonruptured aneurysm and in whom the high-attenuating crescent sign was not present. Acute hemorrhage in the mural thrombus or aneurysmal wall coincident with the high-attenuating crescent sign was present in all six patients with a ruptured aneurysm. Clefts with seeping blood in the mural thrombus were seen in four patients with a ruptured aneurysm; intact specimens of the mural thrombus were not obtained in two patients because the hemorrhagic thrombus was fragile. Clefts with seeping blood were scattered from the inner to the outer layers of the mural thrombus. In the eight patients with uncomplicated aneurysm, no hemorrhage in the mural thrombus or aneurysmal wall was noted, and no clefts were seen. The cause of high-attenuating crescents in a ruptured aneurysm may be attributed to hemorrhage in the mural thrombus or in the aneurysmal wall.

Retained sponge after thoracotomy that mimicked aspergilloma

A 63-year-old man, who had had operation for the treatment of pulmonary tuberculosis 40 years before the present disorder, was admitted to our hospital with massive hemoptysis. Radiologic examinations showed a mass shadow with a crescent air sign resembling aspergilloma. Operative exploration showed a well-encapsulated retained surgical sponge between the middle and lower lobes. A bronchial fistula was present in the lower lobe. The appearance of the crescent air sign was caused by drainage of exudative effusion around the retained sponge. Intrathoracic retained surgical sponges associated with bronchial fistula should be included in the differential diagnosis of patients who have mass shadows with crescent air signs but no evidence of Aspergillus infection, and who have a history of thoracotomy.

Pulmonary mucormycosis

Mucormycosis is an opportunistic, angioinvasive fungal infection characteristically affecting individuals with diabetes mellitus, chronic renal failure, and hematologic malignancies. In most cases it is a rapidly progressive infection with an 80% overall mortality. Radiographic manifestations are usually nonspecific focal consolidation or masses. The air crescent sign is a rare manifestation of angioinvasive fungi and indicates either aspergillosis or mucormycosis.

Varied radiologic appearances of pulmonary aspergillosis.

Pulmonary aspergillosis represents a common, potentially lethal opportunistic infection that has four unique forms: allergic bronchopulmonary aspergillosis (ABPA), aspergilloma, and invasive and semi-invasive aspergillosis. In individuals who are at risk, pulmonary aspergillosis is characterized by a spectrum of clinical and radiographic findings that are intrinsically related to the status of the immune system or the presence of structural lung disease. ABPA, occurring almost exclusively in asthma patients, is characterized radiographically by fleeting pulmonary alveolar opacities caused by deposition of immune complexes and inflammatory cells within the lung parenchyma. Mucus plugging and bronchial wall thickening can be expected in time. Aspergilloma, occurring in patients with structural lung disease, typically appears radiographically as a focal intracavitary mass and is characterized initially by an increase in the wall thickness of a preexisting cavity or cyst. Invasive aspergillosis, which occurs primarily in profoundly immunocompromised patients, may exhibit nonspecific patchy nodular opacities or lobar-type air-space disease in cases with vascular invasion. Computed tomography may reveal a halo or ground-glass attenuation and is more accurate in the detection of early disease. Cavitation often develops with time and typically results in the air crescent sign. Semi-invasive aspergillosis is radiographically similar to the invasive form but differs in clinical course, being associated with mild immunosuppression or chronic illness and typically progressing over the course of months rather than weeks.

Pulmonary zygomycosis: CT appearance.

We describe the CT appearance of pulmonary zygomycosis (mucormycosis), an opportunistic infection typically occurring in immunocompromised patients. Eight patients with pulmonary zygomycosis imaged with CT were reviewed, seven at initial diagnosis and one with a subsequent complication. The appearance, number, and location of pulmonary lesions and the presence of pleural effusions and extrapulmonary involvement were assessed. Rim enhancement, air bronchograms, the halo sign, air crescent sign, cavitation, and central low attenuation suggesting necrosis were recorded. There were 14 nodules and 5 areas of mass-like or wedge-shaped consolidation. Pleural effusion was present in five patients, halo sign in three, central low attenuation in two, and cavitation in one. In the affected lobe 13 of 14 nodules and all consolidations were posterior. Of 19 lesions 16 (84%) were confined to the upper lobes, with 3 in the superior segment of a lower lobe. Endobronchial disease with lobar collapse was the only manifestation in one patient. Major complications were direct spinal invasion in one patient and multiple pulmonary artery pseudoaneurysms in another patient. In the appropriate clinical circumstance, nodules or mass-like or wedge-shaped consolidation, especially posteriorly in the upper lobes of the lung, should suggest zygomycosis. Endobronchial zygomycosis is less common.

Differential diagnosis between intussusception and gastroenteritis by plain film.

The objective of this study is to reassess the validity of plain film diagnosis for pediatric intussusception with consideration of the combinations of radiologic findings. Sixty-six cases of intussusception and 81 controls of gastroenteritis were collected. Their films were read blindly by three radiologists together, with emphasis on nine radiologic findings: sparse colon gas (F1), sparse fecaloid content in colon (F2), gas-filled small bowel loops in right hypochondrium (F3), small bowel obstruction (F4), difficulty in assessing cecum position (F5), pneumoperitoneum (F6), discernible mass lesion (F7), target sign (F8) and crescent sign (F9). The sensitivity and specificity of individual findings and combinations of findings were analyzed. No cases showed F6. Listed in decreasing order of sensitivity, the other eight findings were F1, F5, F2, F7, F3, F4, F9 and F8. The sensitivity and specificity of these eight findings were inversely proportional with significant p-values (F8: < 0.005; the other seven findings: < 0.001). Sixty-three films (95%) in case group displayed combination of at least three radiologic findings. If the diagnostic criteria must consist of at least three radiologic findings, 60 cases (74%) of control group can be excluded. After eliminating the confounding effect of small bowel obstruction on the percentage of gas-filled small bowel loops in right hypochondrium and excluding the data agreed by only one radiologist from the study by Ratcliffe et al, the results of plain film findings were consistent with those of previous reports. The plain abdominal film can play an active role in the diagnosis of pediatric intussusception. Its validity increases when combinations of radiologic findings rather than individual signs are emphasized.

Core decompression of the osteonecrotic femoral head.

The results in 114 hips of ninety-two patients who had osteonecrosis of the femoral head were assessed after treatment with core decompression. The average duration of follow-up was three years and four months (range, two years to six years and six months). The average age of the patients was forty-one years (range, fifteen to sixty-seven years). The presumed risk factors were the use of corticosteroids (thirty-seven hips), excessive use of alcohol (thirty-two hips), trauma (seven hips), and various other factors (seven hips). No specific risk factor was identified for thirty-one hips, and the osteonecrosis was considered to be idiopathic. The preoperative evaluation consisted of clinical assessment, magnetic resonance imaging, and radiographic staging according to a modification of the system of Ficat. Thirty-two hips were in stage I; thirty-eight, in stage IIA; twenty-five, in stage IIB (transition stage, with a crescent sign); and nineteen, in stage III. Clinical failure was defined as the performance of a subsequent operation. Over-all, sixty-four hips (56 percent) failed clinically. Fifty-seven were treated with a hip replacement; four, with a femoral osteotomy; and three, with a vascularized fibular graft. Clinical failure was seen in five (16 percent) of the thirty-two hips in stage I, twenty (53 percent) of the thirty-eight hips in stage IIA, twenty (80 percent) of the twenty-five hips in stage IIB, and in all nineteen of the hips in stage III.(ABSTRACT TRUNCATED AT 250 WORDS)

High-attenuating crescent in abdominal aortic aneurysm wall at CT: a sign of acute or impending rupture.

To determine whether a peripheral high-attenuating crescent in an abdominal aortic aneurysm (AAA) on unenhanced computed tomographic (CT) scans is a sign of impending or active aneurysm rupture. CT scans were reviewed of 149 consecutive patients operated on because of AAA who had undergone preoperative unenhanced CT scanning. The presence of a peripheral high-attenuating crescent on CT scans was correlated with surgical findings of aneurysm complication. Aneurysm diameter was correlated with presence or absence of pain at the time of CT, high-attenuating crescent, and aneurysm complication. Sensitivity of the high-attenuating crescent sign as an indication of complicated aneurysm was 77%; specificity, 93%; and positive predictive value, 53%. The sign showed a statistically significant correlation with large aneurysm size (P < .001) and presence of pain at the time of CT (P < .003). In patients without CT evidence of frank aneurysm leak, the high-attenuating crescent sign should be regarded as a sign of impending AAA rupture, particularly in patients with pain.

Pulmonary Aspergillosis in Patients With AIDS: Clinical and Radiographic Correlations

To evaluate the clinical and radiographic features of pulmonary aspergillosis as they present in AIDS patients; in particular, to determine similarities and differences between Aspergillus infection in patients with AIDS vs those without AIDS. Six new cases of confirmed or probable pulmonary aspergillosis were discovered during a search of hospital records. These are reviewed with 30 previously reported cases with special attention to radiographic appearance of disease and how radiographic appearance influences clinical outcome. Symptoms of pulmonary aspergillosis in AIDS were nonspecific, most often including fever, cough, and dyspnea, and less commonly, chest pain or hemoptysis. Major risk factors for the development of pulmonary aspergillosis in patients with AIDS were steroid administration and neutropenia. Neutropenia was often a complication of therapies for AIDS, in particular, ganciclovir and zidovudine. Radiographic appearance of disease could be divided into three general categories. One third of the patients (13/36) presented with cavitary upper lobe disease resembling noninvasive or chronic necrotizing aspergillosis. Fatal hemoptysis occurred in 42 percent of patients with this form of disease. Twenty-two percent (8/36) of the cases presented as a nondescript focal alveolar opacity similar to invasive aspergillosis. In several patients, the focal infiltrate remained stable for several months, a feature that is unusual for aspergillosis in non-AIDS patients. The air crescent sign was present in none of the 36 reported cases. Patients with only focal disease had the best prognosis of patients with pulmonary aspergillosis. Bilateral alveolar or interstitial disease similar to invasive aspergillosis was present in 23 percent (9/36) of the patients. Bilateral disease appears to be a marker for disseminated infection and was associated with a high mortality due to aspergillosis. Two new forms of bronchial aspergillosis (5/36 cases) have been described previously. These patients presented with either obstructing fungal casts or bronchial pseudomembranes demonstrated bronchoscopically. In some patients with the bronchial forms of aspergillosis, transient alveolar opacities were seen on chest radiographs. These opacities may represent regions of atelectasis due to airway obstruction. One patient who had bilateral pneumothoraces without parenchymal opacities did not correspond to any of the three previously mentioned categories. Mortality due to aspergillosis was greater than 50 percent among AIDS patients. Death was subsequent to fatal hemoptysis or widespread pulmonary or systemic infection. Unlike other risk groups that tend to contract only one form of pulmonary aspergillosis, AIDS patients can develop the whole spectrum of aspergillosis-related pulmonary disorders, including chronic cavitary, invasive, and bronchial forms of aspergillosis. Clinical symptoms are nonspecific and major risk factors include neutropenia, which is often a side effect of various therapies for AIDS, and steroid administration. Patients with the chronic cavitary form of disease have an unusually high mortality due to fatal hemoptysis. Patients with bilateral pulmonary infiltrates and aspergillosis have a high mortality due to disseminated infection.

Pulmonary gangrene and the air crescent sign.

A study was carried out to increase familiarity with the aetiology, pathogenesis, and radiographic features that characterise pulmonary gangrene. Four patients with one of the disorders vasoinvasive aspergillosis, infarcted tuberculous cavity, chronic necrotising aspergillosis, and gangrene due to Pseudomonas aeruginosa were selected because they showed the variations of the typical radiographic pattern and illustrated the pathogenesis. A fifth case is also presented, in which pulmonary gangrene was simulated by the invagination of a loculated pleural effusion into the wall of a contiguous lung abscess. Evolution of a crescent or rim of air within a homogeneous shadow is the feature that both heralds the development and facilitates the recognition of pulmonary gangrene. It is most often the result of vascular thrombosis induced by the infecting organism. The outcome of treatment is often unfavourable, principally because of the severity of the predisposing systemic or local underlying disorder, although a delay in diagnosis, possibly due to unfamiliarity with the radiographic pattern, may have contributed to the adverse outcome in some instances.

Clinical observation of the pulmonary aspergilloma

The authors conducted a clinical observation of 13 cases of pulmonary aspergilloma at Yeungnam University Hospital from March 1983 to March 1992, and the following results were observed : 1) The male to female ratio was 1 : 1.2, and the age distribution was ranged 30 to 67 years old. 2) All cases were symptomatic : hemoptysis, cough, sputum and dyspnea. Especially, hemoptysis was the presenting compliant in 10 patients(77%). 3) The underlying lung disease were pulmonary tuberculosis in 9, COPD in 5 and bronchiectasis in 2, 3 cases were without underlying disease. 4) According to radiographic appearance, 8 cases had the typical crescent sign and 5 cases were seen nodular lesion. And the lesions of 11 cases were located in both upper lung. 5) 10 cases were treated with surgical resection. Among these cases, 8 cases were alieved and 2 cases, died. And other 3 cases were treated with conservative treatment. We suggest that these findings would be helpful for the diagnosis and treatment of pulmonary aspergilloma and further study might be needed to evaluate the prognosis of pulmonary aspergilloma.

The plain abdominal film in intussusception: the accuracy and incidence of radiographic signs.

The incidence of four plain abdominal film features associated with intussusception was recorded by four observers in 180 films of patients with intussusception mixed with 100 films of control subjects. The crescent sign and target sign were the most accurate indicators of intussusception. The target sign was the commoner being seen in 68% of films. Signs of small bowel obstruction were not useful in the diagnosis of intussusception. The soft tissue mass was the commonest indicator of intussusception. The soft tissue mass was found more commonly, however, than small bowel obstruction in the control subjects who did not have intussusception.

Invasive aspergillosis in immunocompromised patients: findings on plain film and (HR)CT

The CT and plain chest film abnormalities in eight patients with invasive pulmonary aspergillosis (IPA) are described and compared. The various radiologic findings of IPA were (sub)segmental and patchy consolidation, cavitation and an air crescent sign. CT had a higher sensitivity for multiplicity of lesions and cavitation compared with the plain chest film. Because these abnormalities are keypoints of the diagnosis, CT is recommended in patients suspected of IPA.

Structural consequences of subchondral bone involvement in segmental osteonecrosis of the femoral head

Appearance of a crescent sign usually marks the onset of necrotic femoral head collapse, but very little is known about which local factors contribute most critically to avoiding or postponing fracture of at-risk juxtaarticular cancellous bone. A three-dimensional finite element model was used to test the hypothesis that an initially mechanically uncompromised subchondral plate could provide a substantial degree of stress protection to a weakened underlying segmental infarction. The computational simulation of osteonecrosis showed that the principal stress distribution for an assumption of subchondral plate weakening (given also an underlying, comparably weakened segmental infarction) differed inappreciably from that of a normal femoral head. However, the tendency for local structural failure, as reflected in the ratio of stress to strength, was substantially higher in the former instance. If, instead, the mechanical integrity of the subchondral plate overlying the weakened segmental infarction was assumed to be preserved, computed stress levels in the at-risk subjacent necrotic cancellous bone were still over 70% as high as for the weakened-plate case. The data thus indicate that even a fully normal subchondral plate can provide only modest stress protection of a weakened underlying segmental infarction, whereas weakening of the necrotic cancellous bone throughout the infarction induces marked stress increase in the overlying subchondral plate. These findings suggest that the onset of collapse is probably dominated much more strongly by the degree of structural degradation of the cancellous bone within the main infarct body, than by the degree of structural degradation within the subchondral plate.

Intrathoracic aspergilloma: role of CT in diagnosis and treatment.

The authors describe the computed tomographic (CT) appearances of aspergilloma in 26 patients. With narrow (3-mm) sections, a bone algorithm, and wide window settings, CT scans enabled accurate identification of both the forming aspergilloma as well as the mature fungus ball in 25 cases. The diagnostic accuracy of CT was confirmed histologically in nine cases. The radiologic concept of the aspergilloma as a solid mass partially surrounded by a crescent of air is no longer tenable as the only definite criterion for diagnosis. In cases in which this classic appearance is seen on CT scans, mobility is easily demonstrated with use of prone and supine positions. In other cases, the aspergilloma appears as an irregular spongework containing air spaces and filling the cavity, obliterating the air crescent sign. The fungus ball is therefore fixed and immobile. Forming aspergillomas can also be identified by the fungal strands that fall into the cavity lumen, trapping air and initiating the sponge-work appearance. The CT appearance in patients with positive precipitins is characteristic and allows earlier diagnosis than does conventional tomography.

The left subphrenic crescent sign in direct cholangiography

Left subdiaphragmatic collections of contrast medium were demonstrated in three patients during cholangiography. All the patients had undergone previous surgery for either biliary, gallbladder or pancreatic disease. The shape of the collections was crescentic and the underlying abnormality was an anterior subdiaphragmatic abscess. Left subphrenic abscesses should therefore be considered when crescentic left subphrenic accumulations of contrast medium occur during cholangiography.

Computerised tomographic demonstration of the „crescent sign” confirming gangrenous sloughing of the lung associated with a primary lung carcinoma

Computerised tomographic demonstration of the „crescent sign” confirming gangrenous sloughing of the lung associated with a primary lung carcinoma

Invasive pulmonary aspergillosis and acute leukemia. Limitations in the diagnostic utility of the air crescent sign.

The air crescent sign is regarded as an important diagnostic finding in invasive pulmonary aspergillosis (IPA). This study examined the incidence, clinical importance, and natural history of air crescents in 25 patients with acute leukemia and IPA. Twelve (50%) of the patients had cavities (ten with an air crescent) that appeared an average of 15 days after the initial infiltrate. The diagnostic utility of the air crescent sign was relatively minor; cavities developed after the diagnosis was established in 50% of cases and after therapy was started in 75% of cases. In each case, the pneumonia improved at the time of cavitation. In six patients (50%), the cavities resolved over 2-8 months. Three patients (25%), however, experienced massive hemoptysis. Air crescent formation, previously shown to be dependent on granulocyte recovery, was associated with improved survival (67%) compared with the group without cavitation (8%). In the latter group, the pneumonia in ten (77%) of 13 patients progressed to diffuse disease. In patients with leukemia, the diagnostic value of the air crescent sign is limited by cavities that develop relatively late, as the infection improves after white blood cell recovery; cavities that do not occur in patients who remain neutropenic; and associated hemorrhage, at times life-threatening, that obscures the air crescent. The diagnosis of IPA should not await observation of air crescents in these patients.

Pathogenesis of Idiopathic Osteonecrosis: The Ubiquitous Crescent Sign

The repair of a large subchondral osteonecrotic lesion follows a precise sequence of biologic events. The repair of osteonecrosis becomes clinically significant with the development of a subchondral fracture manifested radiographically as the crescent sign. Once the subchondral fracture occurs, collapse and subsequent degenerative arthritis are generally inevitable. The repair process, radiologic appearance, and clinical features (pain and loss of function) are identical regardless of the site of the disease.

The air crescent sign of invasive pulmonary aspergillosis in acute leukaemia.

<h3>Introduction</h3> Women may seek abortion at gestations when there is no visible intrauterine pregnancy on ultrasound scanning. Clinical protocols for pregnancy of unknown location (PUL) require measurement of serum human chorionic gonadotrophin (hCG), with the National Institute for Health and Care Excellence recommending that values above 1500 IU/L be further investigated to exclude ectopic pregnancy. Our aim was to determine whether a point-of-care test (POCT) could be used instead of laboratory serum hCG measurement. <h3>Methods</h3> Over 12 months, women who presented to an abortion service with a PUL had a POCT for blood or urine hCG and laboratory serum hCG measurement. The POCT machine used provides a discrete hCG value below 1000 IU/L and above this gives results as a range. The sensitivity and specificity of the POCT in identifying cases where laboratory serum hCG results were above 1500 IU/L were calculated. <h3>Results</h3> A total of 118 women presented with a PUL, of whom 70 had a POCT on blood (n=49) or urine (n=21) and a corresponding laboratory serum hCG. The sensitivity of the blood POCT was 0.67 (95% CI 0.38 to 0.87) and the specificity was 0.97 (95% CI 0.83 to 0.99). The sensitivity of the urine POCT was 0.25 (CI 0.01 to 0.78) and the specificity was 0.94 (CI 0.69 to 0.99). <h3>Conclusion</h3> Although both the blood and urine POCTs had a high level of specificity, neither test was acceptably sensitive. While promising, this POCT for hCG is not sufficiently reliable to replace laboratory serum hCG testing in the management of women with PUL in an abortion service.