Acute Klebsiella pneumoniae pneumonia alone and with concurrent infection: comparison of clinical and thin-section CT findings

The purpose of this study was to identify the clinical and thin-section CT findings in patients with acute Klebsiella pneumoniae pneumonia (KPP) alone and with concurrent infection. We retrospectively identified 160 patients with acute KPP who underwent chest thin-section CT examinations between August 1998 and August 2008 at our institution. The study group comprised 80 patients (54 male, 26 female; age range 18–97 years, mean age 61.5) with acute KPP alone, 55 (43 male, 12 female; age range 46–92 years, mean age 76.0) with KPP combined with methicillin-resistant Staphylococcus aureus (MRSA) and 25 (23 male, 2 female; age range 56–91 years, mean age 72.7) with KPP combined with Pseudomonas aeruginosa (PA). Underlying diseases in patients with each type of pneumonia were assessed. Parenchymal abnormalities were evaluated along with enlarged lymph nodes and pleural effusion. In patients with concurrent pneumonia, underlying conditions such as cardiac diseases, diabetes mellitus and malignancy were significantly more frequent than in patients with KPP alone. The mortality rate in patients with KPP combined with MRSA or PA was significantly higher than in those with KPP alone. In concurrent KPP, CT findings of centrilobular nodules, bronchial wall thickening, cavity, bronchiectasis, nodules and pleural effusion were significantly more frequent with concurrent pneumonia than in those with KPP alone.Klebsiella pneumoniae is among the most common Gram-negative bacteria encountered by physicians worldwide, and accounts for 0.5–5.0% of all cases of pneumonia. It is a clinically important type of pneumonia because of its severity, high incidence of complications and increased mortality [1–3]. The mortality rate in alcoholics with Klebsiella pneumoniae pneumonia (KPP) has been reported to be as high as 50–60% [4, 5].The characteristics of KPP on plain radiography have been described previously [1, 3, 6–9]. Felson et al [8] have studied 14 patients with acute KPP and reported that the presence of certain radiological features supports a diagnosis of acute KPP. These features are bulging fissures, sharp margins of the advancing border of the pneumonic infiltrate and early abscess formation.Recently, we have reported that in 764 of 962 patients (79.4%) with acute KPP, 1 or more additional pathogens, predominantly methicillin-resistant Staphylococcus aureus (MRSA) (36.7%) and Pseudomonas aeruginosa (PA) (23.3%), were found [10].To the best of our knowledge, no studies have compared the pulmonary CT findings in patients with acute and concurrent KPP. Therefore, the present study compared the clinical and pulmonary thin-section CT findings of patients with acute KPP alone and concurrent KPP with MRSA or PA.     

Meticillin-resistant Staphylococcus aureus and meticillin-susceptible S. aureus pneumonia: comparison of clinical and thin-section CT findings

Objectives

The purpose of this study was to compare the clinical and thin-section CT findings in patients with meticillin-resistant Staphylococcus aureus (MRSA) and meticillin-susceptible S. aureus (MSSA).

Methods

We retrospectively identified 201 patients with acute MRSA pneumonia and 164 patients with acute MSSA pneumonia who had undergone chest thin-section CT examinations between January 2004 and March 2009. Patients with concurrent infectious disease were excluded from our study. Consequently, our study group comprised 68 patients with MRSA pneumonia (37 male, 31 female) and 83 patients with MSSA pneumonia (32 male, 51 female). Clinical findings in the patients were assessed. Parenchymal abnormalities, lymph node enlargement and pleural effusion were assessed.

Results

Underlying diseases such as cardiovascular were significantly more frequent in the patients with MRSA pneumonia than in those with MSSA pneumonia. CT findings of centrilobular nodules, centrilobular nodules with a tree-in-bud pattern, and bronchial wall thickening were significantly more frequent in the patients with MSSA pneumonia than those with MRSA pneumonia (p=0.038, p=0.007 and p=0.039, respectively). In the group with MRSA, parenchymal abnormalities were observed to be mainly peripherally distributed and the frequency was significantly higher than in the MSSA group (p=0.028). Pleural effusion was significantly more frequent in the patients with MRSA pneumonia than those with MSSA pneumonia (p=0.002).

Conclusions

Findings from the evaluation of thin-section CT manifestations of pneumonia may be useful to distinguish between patients with acute MRSA pneumonia and those with MSSA pneumonia.Staphylococcus aureus is one of the most common and important pathogens involved in nosocomial pneumonia, particularly because of the development of meticillin-resistant S. aureus (MRSA) [1]. Pneumonia caused by MRSA is a clinically important type of pneumonia because of its severity, the high incidence of complications, and the increased mortality it causes in nosocomial pulmonary infections [2-4].In recent years, MRSA has also emerged as an increasingly important cause of community-acquired bacterial infection, often affecting healthy children and adults who have no apparent risk factors for infection. community-acquired MRSA strains causing life-threatening infections, such as necrotising pneumonia and necrotising fasciitis, have been found to frequently carry Panton–Valentine leukocidin (PVL) genes [5-7].The mortality of pneumonia is usually associated with inadequate initial antibiotic therapy; therefore, early recognition of S. aureus pneumonia is important for reducing morbidity and mortality. Meanwhile bacteriological evaluation may take time and cause a delay in diagnosis. As such, thin-section CT may be helpful in expediting differential diagnosis of infections and in the selection of appropriate antibiotics. Recently, a small number of reports have emerged describing thin-section CT findings in patients with pathogens, including Klebsiella pneumoniae, Mycoplasma pneumoniae and Chlamydia pneumoniae [8-11]. As for S. aureus pneumonia, several studies have shown differences in clinical findings between MRSA pneumonia and meticillin-susceptible S. aureus (MSSA) pneumonia [12-13]. In a radiological study, González et al [14] reported that there were no differences on chest radiographs between 32 patients with MRSA and 54 patients with MSSA. Nguyen and colleagues [15] reported CT findings in nine patients with community-acquired MRSA, whose conditions were characterised by extensive bilateral consolidation and frequent cavitation, which is commonly associated with rapid progression and clinical deterioration. However, there are currently very few reports with radiological findings in patients with MRSA or MSSA pneumonia. Moreover, to the best of our knowledge, no studies describing the comparison of CT findings in patients with MRSA with those with MSSA have been published. As such, the current study sought to evaluate thin-section CT findings of acute MRSA pneumonia compared with those with acute MSSA pneumonia.     

Radiological findings in acute Haemophilus influenzae pulmonary infection

Objective

The aim of this study was to assess pulmonary thin-section CT findings in patients with acute Haemophilus influenzae pulmonary infection.

Methods

Thin-section CT scans obtained between January 2004 and March 2009 from 434 patients with acute H. influenzae pulmonary infection were retrospectively evaluated. Patients with concurrent infection diseases, including Streptococcus pneumoniae (n=76), Staphylococcus aureus (n=58) or multiple pathogens (n=89) were excluded from this study. Thus, our study group comprised 211 patients (106 men, 105 women; age range, 16–91 years, mean, 63.9 years). Underlying diseases included cardiac disease (n=35), pulmonary emphysema (n=23), post-operative status for malignancy (n=20) and bronchial asthma (n=15). Frequencies of CT patterns and disease distribution of parenchymal abnormalities, lymph node enlargement and pleural effusion were assessed by thin-section CT.

Results

The CT findings in patients with H. influenzae pulmonary infection consisted mainly of ground-glass opacity (n=185), bronchial wall thickening (n=181), centrilobular nodules (n=137) and consolidation (n=112). These abnormalities were predominantly seen in the peripheral lung parenchyma (n=108). Pleural effusion was found in 22 patients. Two patients had mediastinal lymph node enlargement.

Conclusion

These findings in elderly patients with smoking habits or cardiac disease may be characteristic CT findings of H. influenzae pulmonary infection.Haemophilus influenzae is an important pneumonia pathogen because of its severity, high incidence of complications and high mortality. This Gram-negative bacillus frequently colonises the human upper respiratory tract, especially the nasopharynx, and is considered to form part of the normal respiratory flora [1]. Most H. influenzae infections are the result of direct extension from the nasopharynx to the lower respiratory tract [1].H. influenzae infection has received increasing attention because it is an important factor in the acute exacerbation of chronic obstructive pulmonary disease (COPD) [1,2]. Acute exacerbation is a frequent event during the prolonged chronic course of COPD, which entails significant morbidity and mortality, and the main aetiology for the majority of episodes is infection.The mortality rate in patients with H. influenzae pneumonia has been reported as 10–42% [3-6]. Moreover, nosocomial outbreaks caused by H. influenzae have been reported [7]. Therefore, it is important to identify the risk factors associated with H. influenzae infection and to evaluate the radiological findings so that no time is lost in initiating appropriate management.Several studies have presented the clinical and microbiological findings in patients with H. influenzae infection [1-4,6,7]. The characteristics of H. influenzae pneumonia on plain radiography have also been described previously [1,8]. Recently, Nei et al [8] have described CT findings of Mycoplasma pneumoniae pneumonia and community-acquired pneumonia caused by other organisms, including 12 patients with H. influenzae pneumonia. The CT finding of bronchial wall thickening in patients with H. influenzae pneumonia was more common than in patients with Streptococcus pneumoniae or Klebsiella pneumoniae.However, to the best of our knowledge, no other English-language studies of pulmonary CT findings in patients with acute H. influenzae pneumonia have been published. This study aimed to assess the clinical findings and pulmonary thin-section CT findings in patients with acute H. influenzae pneumonia.     

Comparison of pulmonary thin section CT findings and serum KL-6 levels in patients with sarcoidosis

Objective

This study aimed to compare thin-section CT images from sarcoidosis patients who had either normal or elevated serum KL-6 levels.

Methods

101 patients with sarcoidosis who underwent thin-section CT examinations of the chest and serum KL-6 measurements between December 2003 and November 2008 were retrospectively identified. The study group comprised 75 sarcoidosis patients (23 male, 52 female; aged 19–82 years, mean 54.1 years) with normal KL-6 levels (152–499 U ml^–1, mean 305.7 U ml^–1) and 26 sarcoidosis patients (7 male, 19 female; aged 19–75 years, mean 54.3 years) with elevated KL-6 levels (541–2940 U ml^–1, mean 802.4 U ml^–1). Two chest radiologists, unaware of KL-6 levels, retrospectively and independently interpreted CT images for parenchymal abnormalities, enlarged lymph nodes and pleural effusion.

Results

CT findings in sarcoidosis patients consisted mainly of lymph node enlargement (70/75 with normal KL-6 levels and 21/26 with elevated KL-6 levels), followed by nodules (50 and 25 with normal and elevated levels, respectively) and bronchial wall thickening (25 and 21 with normal and elevated levels, respectively). Ground-glass opacity, nodules, interlobular septal thickening, traction bronchiectasis, architectural distortion and bronchial wall thickening were significantly more frequent in patients with elevated KL-6 levels than those with normal levels (p<0.001, p<0.005, p<0.001, p<0.001, p<0.001 and p<0.001, respectively). By comparison, there was no significant difference in frequency of lymph node enlargement between the two groups.

Conclusion

These results suggest that serum KL-6 levels may be a useful marker for indicating the severity of parenchymal sarcoidosis.KL-6 is a mucin-like high molecular weight glycoprotein that is expressed on Type II pneumocytes and respiratory bronchiolar epithelial cells in the normal lung [1, 2]. Serum levels of KL-6 are elevated in various respiratory and non-respiratory conditions, including breast and pancreatic cancers [3, 4] and diabetes mellitus [5]. This observation has led to a focus on the use of KL-6 as a diagnostic and prognostic tool in respiratory diseases.Serum and bronchoalveolar lavage fluid levels of KL-6, first described by Kohno et al [6] in 1988, were raised in patients with interstitial pneumonia [1, 2, 7]. Several investigators have also reported that KL-6 is a useful serum marker to confirm diagnosis and for long-term management in patients with diffuse pulmonary diseases, particularly interstitial lung diseases. Patients with idiopathic pulmonary fibrosis or non-specific interstitial pneumonia showed significantly elevated KL-6 levels [8-13].Several studies indicate that the serum KL-6 level is elevated in patients with sarcoidosis [14-16]. However, no studies describing radiological findings comparing thin-section CT images between patients with elevated KL-6 levels and those with normal KL-6 levels have been published in the English language literature.Thus, we aimed to retrospectively evaluate and compare pulmonary CT findings between patients with elevated KL-6 levels and those with normal KL-6 levels.     

Thin-section CT findings of patients with acute Streptococcus pneumoniae pneumonia with and without concurrent infection

Objectives

The aim of this study was to compare the pulmonary thin-section CT findings of patients with acute Streptococcus pneumoniae pneumonia with and without concurrent infection.

Methods

The study group comprised 86 patients with acute S. pneumoniae pneumonia, 36 patients with S. pneumoniae pneumonia combined with Haemophilus influenzae infection, 26 patients with S. pneumoniae pneumonia combined with Pseudomonas aeruginosa infection and 22 patients with S. pneumoniae pneumonia combined with methicillin-susceptible Staphylococcus aureus (MSSA) infection. We compared the thin-section CT findings among the groups.

Results

Centrilobular nodules and bronchial wall thickening were significantly more frequent in patients with pneumonia caused by concurrent infection (H. influenzae: p<0.001 and p<0.001, P. aeruginosa: p<0.001 and p<0.001, MSSA: p<0.001 and p<0.001, respectively) than in those infected with S. pneumoniae alone. Cavity and bilateral pleural effusions were significantly more frequent in cases of S. pneumoniae pneumonia with concurrent P. aeruginosa infection than in cases of S. pneumoniae pneumonia alone (p<0.001 and p<0.001, respectively) or with concurrent H. influenzae (p<0.05 and p<0.001, respectively) or MSSA infection (p<0.05 and p<0.05, respectively).

Conclusions

When a patient with S. pneumoniae pneumonia has centrilobular nodules, bronchial wall thickening, cavity or bilateral pleural effusions on CT images, concurrent infection should be considered.Streptococcus pneumoniae has long been recognised as the most common cause of community-acquired pneumonia (CAP) and is responsible for the increasing frequency of nosocomial pneumonia [1-3]. The mortality associated with pneumonia is linked to inadequate initial antibiotic therapy; therefore, early detection of S. pneumoniae pneumonia is important for reducing morbidity and mortality.A rapid immunochromatographic membrane test was developed for the detection of S. pneumoniae antigens in urine samples [4]. It is a useful technique for the rapid diagnosis of pneumococcal pneumonia; however, the urinary antigens cannot be detected a few days after S. pneumoniae infection, and this test is unable to detect concurrent pathogen infections.Most cases of CAP are probably caused by a single pathogen, but dual or multiple infections have been increasingly reported in the literature [5-8]. There is growing concern for the concurrent presence of a second pathogen in a significant proportion of cases of CAP previously thought to be monomicrobial [5,7-10]. De Roux et al [8] reported that in 82 patients with mixed CAP, S. pneumoniae was the most prevalent microorganism (n=44), that the most frequent combination of organisms was S. pneumoniae with Haemophilus influenzae (n=17) and that patients with mixed pyogenic pneumonia more frequently developed shock than patients with single pyogenic pneumonia.The classic chest radiographic appearances of pneumococcal pneumonia have been described as sublobar, lobar or multilobar opacities, often homogeneous with an air bronchogram [11-13]. As for CT findings, a few studies have been reported in patients with S. pneumoniae pneumonia; Miyashita et al [14] reported CT findings in 68 patients with S. pneumoniae pneumonia who were not infected with any other microorganisms.However, to the best of our knowledge, no studies have been published that compare CT findings in patients with S. pneumoniae pneumonia alone with those displaying concurrent pneumonia caused by S. pneumoniae and another pathogen. The present study therefore compared the pulmonary thin-section CT findings of patients with acute S. pneumoniae pneumonia alone with those of patients with concurrent S. pneumoniae pneumonia.     

Pulmonary thin-section CT findings in acute Moraxella catarrhalis pulmonary infection

Objective

Moraxella catarrhalis is an important pathogen in the exacerbation of chronic obstructive pulmonary disease. The aim of this study was to assess the clinical and pulmonary thin-section CT findings in patients with acute M. catarrhalis pulmonary infection.

Methods

Thin-section CT scans obtained between January 2004 and March 2009 from 292 patients with acute M. catarrhalis pulmonary infection were retrospectively evaluated. Clinical and pulmonary CT findings in the patients were assessed. Patients with concurrent infection including Streptococcus pneumoniae (n = 72), Haemophilus influenzae (n = 61) or multiple pathogens were excluded from this study.

Results

The study group comprised 109 patients (66 male, 43 female; age range 28–102 years; mean age 74.9 years). Among the 109 patients, 34 had community-acquired and 75 had nosocomial infections. Underlying diseases included pulmonary emphysema (n = 74), cardiovascular disease (n = 44) or malignant disease (n = 41). Abnormal findings were seen on CT scans in all patients and included ground-glass opacity (n = 99), bronchial wall thickening (n = 85) and centrilobular nodules (n = 79). These abnormalities were predominantly seen in the peripheral lung parenchyma (n = 99). Pleural effusion was found in eight patients. No patients had mediastinal and/or hilar lymph node enlargement.

Conclusions

M. catarrhalis pulmonary infection was observed in elderly patients, often in combination with pulmonary emphysema. CT manifestations of infection were mainly ground-glass opacity, bronchial wall thickening and centilobular nodules.Moraxella catarrhalis is a Gram-negative, aerobic, oxidase-positive diplococcus that was first described in 1896 [1]. The pathogen, also known as Micrococcus catarrhalis, Neisseria catarrhalis and Brahamella catarrhalis, is a clinically important pathogen and is a common cause of respiratory infections, particularly otitis media in children and lower respiratory tract infection in elderly patients [2-5]. M. catarrhalis is considered to be the third most common and most important cause of bronchopulmonary infections after Streptococcus pneumoniae and Haemophilus influenzae [6,7]. In the Alexander project in Europe and the US between 1992 and 1993, M. catarrhalis was identified in 13.5% of bacterial isolates [8].M. catarrhalis has also gained attention as a nosocomial respiratory pathogen and as a community-acquired pathogen. On the basis of epidemiological evidence, the spread of M. catarrhalis was suggested to occur within the hospital environment [9,10]. McLeod et al [11] reported that 43 of 81 patients (53%) with M. catarrhalis infection were infected in a hospital and that the infection was associated with the proximity of the patient to other patients. Most nosocomial infections with M. catarrhalis involve the respiratory tract and outbreaks have been reported in respiratory units and paediatric intensive care units [10,12].M. catarrhalis infection has received increasing attention because it is an important factor in the acute exacerbation of chronic obstructive pulmonary disease (COPD). Acute exacerbation is a frequent event during the prolonged chronic course of COPD, which entails significant morbidity and mortality. The main aetiology for the majority of episodes is infection.Al-Anazi et al [13] reported a CT image of pneumonia associated with M. catarrhalis in a haematopoietic stem cell transplant patient. However, to the best of our knowledge, no other English-language studies of pulmonary CT findings in patients with acute M. catarrhalis pulmonary infection have been published. Therefore, this study aimed to assess the clinical and pulmonary thin-section CT findings in acute M. catarrhalis pulmonary infection.     

A comparative study of thin-section CT findings between seasonal influenza virus pneumonia and Streptococcus pneumoniae pneumonia

Objective:

To compare the pulmonary thin-section CT findings in patients with seasonal influenza virus pneumonia with Streptococcus pneumoniae pneumonia.

Methods:

The study group included 30 patients (20 males and 10 females; age range, 20–91 years; mean age, 55.9 years) with seasonal influenza virus pneumonia and 71 patients (47 males and 24 females; age range, 27–92 years; mean age, 67.5 years) with S. pneumoniae pneumonia.

Results:

The proportion of community-acquired infection was significantly higher in patients with influenza virus pneumonia than with S. pneumoniae pneumonia (p = 0.001). CT findings of ground-glass attenuation (GGA) (p = 0.012) and crazy-paving appearance (p = 0.03) were significantly more frequent in patients with influenza virus pneumonia than with S. pneumoniae pneumonia. Conversely, consolidation (p < 0.001), mucoid impaction (p < 0.001), centrilobular nodules (p = 0.04) and pleural effusion (p = 0.003) were significantly more frequent in patients with S. pneumoniae pneumonia than in those with influenza virus pneumonia.

Conclusion:

Pulmonary thin-section CT findings, such as consolidation and mucoid impaction may be useful in distinguishing between seasonal influenza virus pneumonia and S. pneumoniae pneumonia.

Advances in knowledge:

(1) Distinguishing seasonal influenza virus pneumonia with S. pneumoniae pneumonia is important. (2) The CT findings of GGA and crazy-paving appearance were more frequently found in patients with influenza virus pneumonia than in patients with S. pneumoniae pneumonia, whereas consolidation, mucoid impaction, centrilobular nodules and pleural effusion were more frequently found in patients with S. pneumoniae pneumonia.Influenza virus is responsible for seasonal epidemics of community-acquired pneumonia (CAP), with outbreaks occurring predominantly during the winter months. Secondary bacterial superinfections are the most frequent complications among fatal cases of seasonal and pandemic influenza.Streptococcus pneumoniae is the most common pathogen of CAP and is also responsible for the increasing frequency of nosocomial pneumonia.^1–3 The mortality related with pneumonia is affected by initial antibiotic therapy; therefore, early detection of S. pneumoniae pneumonia is important for reducing mortality. Moreover, S. pneumoniae has been identified as the most prominent causative agent for secondary bacterial pneumonia following influenza virus infection.⁴A rapid immunochromatographic membrane test was developed for the detection of S. pneumoniae antigens.⁵ It is a useful technique for the rapid diagnosis of S. pneumoniae pneumonia; however, it does have its limitations. For example, urinary antigens of S. pneumoniae pneumonia cannot be detected a few days after S. pneumoniae infection, and assay sensitivity is approximately 70–80%.There are several reports of the radiologic features of novel influenza virus pneumonia and S. pneumoniae pneumonia.^6–8 However, there are few reports of the CT findings of seasonal influenza virus pneumonia.^9–11 Furthermore, to the best of our knowledge, no studies comparing CT findings in patients with seasonal influenza virus pneumonia to those with S. pneumoniae pneumonia have been published. The present study therefore compared the pulmonary thin-section CT findings of patients with seasonal influenza virus pneumonia to those with S. pneumoniae pneumonia.     

CT in the clinical and prognostic evaluation of acute graft-vs-host disease of the gastrointestinal tract

Objective

To determine the role of abdominal CT in assessment of severity and prognosis of patients with acute gastrointestinal (GI) graft-vs-host disease (GVHD).

Methods

During 2000–2004, 41 patients with a clinical diagnosis of acute GI-GVHD were evaluated. CTs were examined for intestinal and extra-intestinal abnormalities, and correlated with clinical staging and outcome.

Results

20 patients had GVHD clinical Stage I–II and 21 had Stage III–IV. 39 (95%) had abnormal CT appearances. The most consistent finding was bowel wall thickening: small (n=14, 34%) or large (n=5, 12%) bowel, or both (n=20, 49%). Other manifestations included bowel dilatation (n=7, 17%), mucosal enhancement (n=6, 15%) and gastric wall thickening (n=9, 38%). Extra-intestinal findings included mesenteric stranding (n=25, 61%), ascites (n=17, 41%), biliary abnormalities (n=12, 29%) and urinary excretion of orally administered gastrografin (n=12, 44%). Diffuse small-bowel thickening and any involvement of the large bowel were associated with severe clinical presentation. Diffuse small-bowel disease correlated with poor prognosis. 8 of 21 patients responded to therapy, compared with 15 of 20 patients with other patterns (p=0.02), and the cumulative incidence of GVHD-related death was 62% and 24%, respectively (p=0.01). Overall survival was not significantly different between patients with diffuse small-bowel disease and patients with other patterns (p=0.31). Colonic disease correlated with severity of GVHD (p=0.04), but not with response to therapy or prognosis (p=0.45).

Conclusion

GVHD often presented with abdominal CT abnormalities. Diffuse small-bowel disease was associated with poor therapeutic response. CT may play a role in supporting clinical diagnosis of GI GVHD and determining prognosis.Allogeneic stem-cell transplantation (SCT) has been used increasingly to treat haematopoietic disorders and haematological malignancies [1,2]. Among the complications of SCT, graft-vs-host disease (GVHD) is one of the major causes of morbidity and mortality [3-5]. Intestinal GVHD is one of the most frequent features of acute GVHD. Gastrointestinal (GI) symptoms include abdominal pain, nausea, vomiting and profuse diarrhoea [5-8]. The diagnosis and grading of the disease are based on a spectrum of clinical and laboratory features. Clinical parameters such as the quantity of diarrhoea are used to determine the clinical severity of GI GVHD [9]. These are, however, not very accurate, as assessment of the volume of diarrhoea is inconvenient and inaccurate. Endoscopic evaluation, with histological examination of biopsy specimens, can be useful for diagnosing and staging intestinal GVHD [10-12]. However, GI biopsies may be hazardous in patients with severe thrombocytopenia, coagulopathy and granulopenia [13]. Moreover, both endoscopic evaluation and histology can underestimate the severity of the disease [14].Recently, non-invasive methods have been used to assess the extent and severity of intestinal GVHD, including CT [15-20], high-resolution ultrasonography [21,22], MRI [23] and positron emission tomography with fluorodeoxyglucose (PET-FDG) [24]. Abdominal CT has been the main modality, showing abnormal findings in gastrointestinal GVHD [16,25] which correlate with both pathological [18] and clinical grading [20]. No study has as yet tried to correlate these CT findings with the outcome of the disease. This study was therefore designed to determine the role of abdominal CT in the assessment of severity and prognosis of patients with acute intestinal GVHD.     

Miliary tuberculosis: a comparison of CT findings in HIV-seropositive and HIV-seronegative patients

The aim of this study was to determine the differences in CT findings of miliary tuberculosis in patients with and without HIV infection. Two radiologists reviewed retrospectively the CT findings of 15 HIV-seropositive and 14 HIV-seronegative patients with miliary tuberculosis. The decisions on the findings were reached by consensus. Statistical analysis was performed using the χ² test, Mann–Whitney U-test and Fisher''s exact test. All of the HIV-seropositive and -seronegative patients had small nodules and micronodules distributed randomly throughout both lungs. HIV-seropositive patients had a higher prevalence of interlobular septal thickening (p = 0.017), necrotic lymph nodes (p = 0.005) and extrathoracic involvement (p = 0.040). The seropositive patients had a lower prevalence of large nodules (p = 0.031). In conclusion, recognition of the differences in the radiological findings between HIV-seropositive and -seronegative patients may help in the establishment of an earlier diagnosis of immune status in patients with miliary tuberculosis.Miliary tuberculosis (TB), which results from lympho-haematogenous dissemination of Mycobacterium tuberculosis, is a complication of both primary and post-primary TB [1, 2]. This disease results in the formation of small discrete foci of granulomatous tissue, which are uniformly distributed throughout the lung [3].An increase in TB incidence, including miliary TB, has been associated with infection by human immunodeficiency virus (HIV) [4]. In 2005, the World Health Organization estimated that 12% of HIV deaths globally were caused by TB, and that there were 630 000 new co-infections with TB and HIV [5]. Disseminated TB accounted for 5.4–8.1% of culture-confirmed TB cases, with 10–14% of patients coinfected with HIV having clinically recognisable dissemination [6, 7].Chest radiography may be helpful in the detection and final diagnosis of miliary TB. The characteristic radiographical findings consist of the presence of fine granular or numerous small nodular opacities measuring 1–3 mm in diameter scattered throughout both lungs [1, 3, 8, 9]. However, the radiograph may appear to be normal in the early stage of disease or in cases with nodules below the threshold of perceptibility; therefore, a diagnosis of miliary TB from chest radiographs can be difficult [10].Several studies have shown that CT imaging is more sensitive for the detection of parenchymal abnormalities in patients with AIDS who have active intrathoracic disease, and it has been suggested that CT may also be helpful in the differential diagnosis [11–14]. In addition, it has been reported that certain imaging techniques provided by multidetector-row CT are useful for the diagnosis of multiple micronodular infiltrative lung disease [15]. CT findings of miliary TB have been described in previous reports [16–18]; however, only a few studies on miliary TB in patients with HIV, particularly with reference to the CD4 count, have been reported [19, 20]. The radiographic manifestations of HIV-associated pulmonary TB are thought to be dependent upon the level of immunosuppression at the time of overt disease [21–23].The purpose of this study was to determine the differences in the CT findings of miliary TB for patients with and without HIV infection and to analyse any correlation between the CT features and the level of immunosuppression in patients.     

MRI features of serous oligocystic adenoma of the pancreas: differentiation from mucinous cystic neoplasm of the pancreas

Objectives

The purpose of this study was to describe the MRI features of the benign pancreatic neoplasm serous oligocystic adenoma (SOA) that differ from those of mucinous cystic neoplasm (MCN), a neoplasm with the potential for malignant degeneration.

Methods

Seven patients with SOA (seven women; mean age 36.6 years) and eight patients with MCN (eight women: mean age 39.9 years) were included. Several imaging features were reviewed: mass size, location, shape, wall thickness, cyst configuration (Type I, unilocular; Type II, multiple clustered cyst; Type III, cyst with internal septation) and signal intensity of the lesion with heterogeneity.

Results

SOA lesions were smaller (3.4 cm) than those of MCN (9.3 cm) (p=0.023). The commonest lesion shape was lobulated (85.7%) for SOA, but oval (50.0%) or lobulated (37.5%) for MCN (p=0.015). The most common cyst configuration was Type II (85.7%) for SOA and Type III (75.0%) for MCN (p=0.008). Heterogeneity of each locule in T₁ weighted images was visible in all cases of MCN, but in no case for SOA (p=0.004).

Conclusion

SOA could be differentiated from MCN by identifying the imaging features of lobulated contour with multiple clustered cyst configurations and homogeneity of each locule in T₁ weighted MR images.Serous oligocystic adenoma (SOA) is a recently described rare, benign pancreatic neoplasm and a morphological variant of serous microcystic adenoma, because it contains six or fewer cysts and the cysts are large (>2 cm) [1,2]. Pathologically, SOA is a benign pancreatic neoplasm composed of a few relatively large cysts uniformly lined with glycogen-rich cuboidal epithelial cells [3]. According to the World Health Organization classification, SOA is a subgroup of pancreatic serous cystic tumours and the term SOA is a synonym for macrocystic serous cystadenoma [3,4].The CT and MRI features of SOA of the pancreas are documented [2]. On CT and MRI, SOA typically appears as a small unilocular or bilocular cyst (<5 cm) with a thin wall (<2 mm) that lacks mural nodules or calcifications [2]. Because the cystic spaces are >2 cm, SOA images can be mistaken for mucinous cystic neoplasm (MCN), pseudocyst or intraductal papillary mucinous tumour [2,5-7]. It is very difficult to differentiate SOA from MCN by clinical and radiological features [2,6,8,9]. SOA does not require resection unless it causes symptoms, but MCN should be resected because of a potential for malignant degeneration [5,7,8]. Endoscopic ultrasound and cyst fluid aspiration have a role in distinguishing mucinous and serous lesions, but it is an invasive procedure with a risk of complications such as pancreatitis [10]. Therefore, it is clinically valuable to determine characteristic imaging findings that can distinguish SOA from MCN.Recently, Kim et al [6] and Cohen-Scali et al [5] described characteristic CT findings that can be used to differentiate SOA from MCN. MRI can demonstrate septa within a lesion with greater sensitivity than CT; therefore, MRI provides a better evaluation of tissue characteristics than CT [1,11]. However, few studies have described the MRI features of SOA [1,2]. The purpose of this study was to describe the differences in the MRI features of SOA and MCN in the pancreas.     

Prognostic factors associated with a subchondral insufficiency fracture of the femoral head

Objective

The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF).

Methods

Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh’s index, were documented. The morphological characteristics of the low-intensity band on T₁ weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre).

Results

Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values.

Conclusion

These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.Subchondral insufficiency fractures of the femoral head (SIF) often occur in osteoporotic elderly patients [1-9]. Patients usually suffer from acute hip pain without any obvious antecedent trauma. Radiologically, a subchondral fracture is seen primarily in the superolateral portion of the femoral head [4,5,10]. T₁ weighted MRI reveal a very low-intensity band in the subchondral area of the femoral head, which tends to be irregular, disconnected and convex to the articular surface [2,4,5,7,9,11]. This low-intensity band in SIF was histologically proven to correspond with the fracture line and associated repair tissue [5,9]. Some cases of SIF resolve after conservative treatment [5,11-14]; other cases progress until collapse, thereby requiring surgical treatment [4-10,15]. The prognosis of SIF patients remains unclear.The current study investigated the risk factors that influence the prognosis of SIF based on the progression to collapse.     

Non-osseous incidental findings in low-dose whole-body CT in patients with multiple myeloma

Objective:

The purpose of this study was to identify the frequency and grading of non-osseous incidental findings (NOIF) in non-contrast whole-body low-dose CT (LDCT) in patients with multiple myeloma.

Methods:

In the time period from 2010 to 2013, 93 patients with multiple myeloma were staged by non-contrast whole-body LDCT at our radiological department. LDCT images were analysed retrospectively for NOIF, which also included unsuspected extramedullary manifestation of multiple myeloma. All NOIF were classified as major or clinically significant, moderate or possibly clinically significant and minor or not clinically significant. Medical records were analysed regarding further investigation and follow-up of the identified NOIF.

Results:

In the 93 patients, 295 NOIF were identified (on average, 3.2 NOIF per patient). Most of the NOIF (52.4%) were not clinically significant, 25.8% of the NOIF were possibly clinically significant and 21.8% of the NOIF were clinically significant. Clinically significant NOIF were investigated further by CT after intravenous administration of contrast medium and/or by ultrasound or MRI. In 34 of these cases, extramedullary relapse of myeloma, occult carcinoma or infectious/septic incidental findings were diagnosed (11.5% of all NOIF). In the remaining 10.3% of the NOIF classified as clinically significant, various benign lesions were diagnosed.

Conclusion:

LDCT detected various non-osseous lesions in patients with multiple myeloma. 36.6% of the patients had clinically significant NOIF. Therefore, LDCT examinations in patients with multiple myeloma should be evaluated carefully for the presence of NOIF.

Advances in knowledge:

LDCT identified several NOIF. A total of 36.6% of patients with multiple myeloma had clinically significant NOIF. Radiologists should analyse LDCT examinations in patients with multiple myeloma not only for bone lesions, but also for lesions in other organs.CT is used for screening or staging in several malignancies.^1–8 As reported previously, the staging CT examination also provides additional information regarding the general health status of the patient or so-called incidental findings (IF).^1,3,6,7 Several IF on CT examinations were described in the literature.^1–6 According to previous reports, IF can be classified into five different categories: Group “0”, limited examination, that is, evaluation of IF are severely limited; Group “1”, normal findings or anatomic variant; Group “2”, clinically unimportant findings, such as liver or kidney cysts; Group “3”, likely unimportant findings; and Group “4”, potentially important findings, such as solid renal masses or lymphadenopathy.⁵ In another publication, a three-part classification of IF according to their clinical importance was proposed, namely major, moderate and minor IF.¹Most of the IF are clinically non-significant, such as colonic diverticula or simple cysts.^1–7 However, serious IF, such as aortic aneurysm or dissection, thrombosis, pulmonary embolism and second primary tumours, can also occur,^1,3,6,7 and some of them may be not visible on low-dose CT (LDCT).Most reports regarding IF are based on contrast-enhanced CT.^1,7,9–11 There are only a few reports regarding IF in LDCT.¹² They described IF in screening programmes for lung cancer and based the findings on thoracic LDCT only.¹² In addition, non-contrast LDCT has been established for staging of bone lesions in multiple myeloma.^13–16 However, radiologists should analyse LDCT examinations not only for bone lesions but also for lesions in other organs, which may include extramedullary manifestation of multiple myeloma as well as unrelated IF.Although IF in multiple myeloma have also been described previously,¹⁴ to the best of our knowledge, there exists no analysis focused on frequency and distribution of non-osseous IF (NOIF) on whole-body LDCT. Therefore, the purpose of this study was to identify the frequency and grading of NOIF in non-contrast whole-body LDCT in patients with multiple myeloma.     

Acute appendicitis: relationships between CT-determined severities and serum white blood cell counts and C-reactive protein levels

Objectives

The aim of this study was to evaluate the relationships between the severity of appendicitis as depicted on CT and blood inflammatory markers of serum white blood cell (WBC) count and C-reactive protein (CRP).

Methods

CT images in 128 patients (109 surgically proven and 19 with clinically excluded appendicitis) were retrospectively reviewed. Two radiologists by consensus evaluated and scored (using a 0, 1 or 2 point scale) severities based on CT-determined appendiceal diameters, appendiceal wall changes, caecal changes, periappendiceal inflammatory stranding and phlegmon or abscess formation. We investigated whether CT findings were significantly related to elevated WBC counts or CRP levels and performed the correlations of WBC counts and CRP levels with CT severity scores. Patients were also subjectively classified using four grades from normal (Grade I) to perforated appendicitis (Grade IV) on the basis of CT findings to evaluate differences in WBC counts and CRP levels between grades.

Results

Only appendiceal wall changes and the phlegmon or abscess formation were related to elevated WBC counts and CRP levels, respectively (p<0.05). CT severity scores were found to be more strongly correlated with CRP levels (r = 0.669) than with WBC counts (r = 0.222). On the basis of CT grades, the WBC counts in Grade I were significantly lower than in other grades (p<0.001), whereas CRP levels in Grade IV were significantly higher than in other grades (p<0.001).

Conclusion

CRP levels were found to correlate with CT-determined acute appendicitis severity and could be a useful predictor for perforated appendicitis, whereas WBC counts might be useful to detect early acute appendicitis.Acute appendicitis is one of the most common surgical conditions in patients with right lower quadrant pain. Acute appendicitis is usually diagnosed on the basis of clinical findings such as fever, right lower quadrant pain and tenderness and muscle guarding [1]. However, the accuracy of clinically based diagnoses depends on clinician experience and has been reported to range from 71% to 97% [2]. By contrast, ultrasonography and CT have substantially increased the accuracy of diagnosing acute appendicitis. In particular, multidetector row CT (MDCT) has been reported to be highly accurate and effective at diagnosing acute appendicitis [3,4].We have observed that in many institutions blood inflammatory markers such as white blood cell (WBC) counts and C-reactive protein (CRP) levels are performed in patients suspected of having acute appendicitis. In fact, some investigators have stressed the importance of these blood inflammatory markers in the context of deciding upon discharge or admission for further investigation [5-10]. However, some reports show that these inflammatory markers have low diagnostic accuracy in acute appendicitis [11-13]. As a result of these disparate results, the importance of WBC counts and CRP levels during the diagnostic stage remains controversial.Some articles conclude that WBC counts and CRP levels are reliable indicators of disease severity and that they are significantly correlated with pathological findings [5,9]. In addition, a small number of studies have reported that CT findings are significantly correlated with surgical–pathological severity [14,15]. However, to the best of our knowledge, no study has been performed on the relationship between the CT findings of acute appendicitis and WBC counts or CRP levels. Accordingly, we undertook this retrospective study to evaluate these relationships in patients with acute appendicitis.     

Adrenal venous sampling for stratifying patients for surgery of adrenal nodules detected using dynamic contrast enhanced CT

PURPOSE

We aimed to assess the value of adrenal venous sampling (AVS) for diagnosing primary aldosteronism (PA) subtypes in patients with a unilateral nodule detected on adrenal computed tomography (CT) and scheduled for adrenalectomy.

MATERIALS AND METHODS

This retrospective study included 80 consecutive patients with PA undergoing CT and AVS. Different lateralization indices were assessed, and a cutoff established using receiver operating characteristic curve analysis. The value of CT alone versus CT with AVS for differentiating PA subtypes was compared. The adrenalectomy outcome was assessed, and predictors of cure were determined using univariate analysis.

RESULTS

AVS was successful in 68 patients. A cortisol-corrected aldosterone affected-to-unaffected ratio cutoff of 2.0 and affected-to-inferior vena cava ratio cutoff of 1.4 were the best lateralization indices, with accuracies of 82.5% and 80.4%, respectively. CT and AVS diagnosed 38 patients with aldosterone-producing adenomas, five patients with unilateral adrenal hyperplasia, and 25 patients with bilateral adrenal hyperplasia. Of the 52 patients with a nodule detected on CT, subsequent AVS diagnosed bilateral adrenal hyperplasia in 14 patients (27%). Compared to the results of combining CT with AVS, the accuracy of CT alone for diagnosing aldosterone-producing adenomas was 71.1% (P < 0.001). The cure rate for hypertension after adrenalectomy was 39.2%, with improvement in 53.5% of patients. On univariate analysis, predictors of persistent hypertension were male gender and preoperative systolic blood pressure.

CONCLUSION

To avoid inappropriate surgery, AVS is necessary for diagnosing unilateral nodules with aldosterone hypersecretion detected by CT.Primary aldosteronism (PA) is the most common form of secondary hypertension, with a prevalence of 5%–11% (1–3). PA is due primarily to the hypersecretion of aldosterone by an aldosterone-producing adenoma (APA) or unilateral (primary) adrenal hyperplasia (UAH), which constitute 30%–40% of cases; the remainder are presumed to be secondary to idiopathic bilateral adrenal hyperplasia (BAH) (1, 4, 5). APA and UAH are two forms of unilateral aldosterone hypersecretion, and both are curable with adrenalectomy. BAH induces bilateral aldosterone hypersecretion, and anti-aldosterone drugs are used in its medical management (5–7).The plasma aldosterone-to-renin ratio is used to screen for PA in patients at high risk for PA (8). Recent guidelines recommend using computed tomography (CT) of the adrenal gland to categorize the subtype after confirming PA. However, CT cannot reliably visualize a microadenoma or distinguish between an incidentaloma or BAH and APA. It has been suggested that adrenal venous sampling (AVS) be performed to determine the subtype of PA and to differentiate between unilateral and bilateral production of aldosterone preoperatively (9). AVS to measure the adrenal vein aldosterone and cortisol is the gold standard for lateralizing aldosterone secretion (10). Lateralization is defined using several ratios. In patients with APA or UAH, a unilateral adrenalectomy results in a complete cure or improved hypertension and potassium normalization in approximately 30% of patients, with reported rates up to 86% (11–15).This study assessed several lateralization ratios to establish the most predictive of unilateral disease. We also compared the CT results with those of bilateral AVS for differentiating the PA subtype, with the assumption that AVS is necessary before surgery, even in patients with nodules <10 mm detected with CT. Finally, we assessed the outcomes of adrenalectomy in our patients to identify preoperative predictors of a good outcome.     

Accessory or additional renal arteries show no relevant effects on the width of the upper urinary tract: a 64-slice multidetector CT study in 1072 patients with 2132 kidneys

Objective

The aim of this study was to find out on an unselected patient group whether crossing vessels have an influence on the width of the renal pelvis and what independent predictors of these target variables exist.

Methods

In this cross-sectional study, 1072 patients with arterially contrasted CT scans were included. The 2132 kidneys were supplied by 2736 arteries.

Results

On the right side, there were 293 additional and accessory arteries in 286 patients, and on the left side there were 304 in 271 patients. 154 renal pelves were more than 15 mm wide. The greatest independent factor for hydronephrosis on one side was hydronephrosis on the contralateral side (p<0.0001 each). Independent predictors for the width of the renal pelvis on the right side were the width of the renal pelvis on the left, female gender, increasing age and height; for the left side, predictors were the width of the renal pelvis on the right, concrements, parapelvic cysts and great rotation of the upper pole of the kidney to dorsal. Crossing vessels had no influence on the development of hydronephrosis. Only anterior crossing vessels on the right side are associated with widening of the renal pelvis by 1 mm, without making it possible to identify the vessel as an independent factor in multivariate regression models.

Conclusion

The width of the renal pelvis on the contralateral side is the strongest independent predictor for hydronephrosis and the width of the renal pelvis. There is no link between crossing vessels and the width of the renal pelvis.Obstructions of the ureteropelvic junction (UPJ) can be caused by intrinsic or extrinsic factors [1]. Although there are no studies of this to date, crossing the UPJ by an aberrant crossing vessel is considered the most important [2] of the extrinsic factors [3]. Crossing vessels, which are thought to cause from 40% to over 50% of the extrinsic UPJ obstructions in adults [4, 5], are located ventral more often than dorsal to the UPJ. These are usually normal vessels of the lower pole segment [4, 6–9], which can be divided into additional renal arteries arising from the aorta, and accessoric renal arteries arising from branches of the aorta [10, 11]. The primary surgical therapy of choice is endoscopic endopyelotomy [12]. The success rate of 89–90% [12, 13] is thought to be noticeably poorer in patients with crossing vessels [12, 13]; however, this is not undisputed [14, 15]. Be that as it may, to prevent bleeding complications it is necessary to be familiar with the vascular situation around the UPJ prior to the procedure [3, 16–18]. CT angiography is used for this purpose, as it is highly accurate, quick to perform and shows all relevant anatomical structures in relation to one another [3, 19, 20]. The objective of this study was to determine whether or not there are vascular morphological patterns or other factors that influence the width of the renal collecting system, regardless of the definitions of hydronephrosis.     

Multidetector CT findings in patients with mesenteric ischaemia following cardiopulmonary bypass surgery

Objective:

To investigate CT findings in patients with pathologically proven mesenteric ischaemia post-cardiopulmonary bypass surgery and compare them with the control group of patients without ischaemia.

Methods:

68 patients were identified by a search of local surgical and pathological databases; these patients met the inclusion criteria of a laparotomy within 1 month of a procedure requiring cardiopulmonary bypass and a CT abdomen/pelvis within 1 week of the pathological diagnosis. Two radiologists independently reviewed the studies, evaluating 17 separate findings relating to the bowel, the vasculature or other structures; consensus was subsequently reached. The diagnostic value of CT findings was assessed using logistic regression.

Results:

52 of 68 patients had pathologically proven ischaemia. Portal venous gas, mesenteric venous gas and small bowel faeces sign all had specificities of >0.94 for ischaemia but low sensitivity (<0.27). Differential mural enhancement had high sensitivity (0.92) but poor specificity (0.50). The combination of pneumatosis, bowel loop dilatation and differential mural enhancement predicted bowel ischaemia with a probability of 98%. The hardest signs to interpret based on poor interreader kappa agreement were bowel wall thinning, mesenteric stranding and differential mural enhancement.

Conclusion:

A combination of CT signs was predictive of ischaemic bowel; however, the more specific findings lacked sensitivity. If clinical suspicion is high for bowel ischaemia, prompt surgical intervention is warranted, regardless of CT findings.

Advances in knowledge:

Arterial occlusion was uncommon and venous occlusion was not present, which is supportive of a predominantly non-occlusive aetiology for ischaemia in this patient group.Mesenteric ischaemia with resulting bowel infarction is a potentially life-threatening complication following cardio-pulmonary bypass (CPB) surgery. The frequency following such operations is rare (0.49–2.00%) [1–3]; however, the mortality from acute mesenteric ischaemia of any aetiology is high at 70–100%, even for patients managed in specialist tertiary referral centres [4–6]. Although there has been a recent move away from coronary artery bypass graft (CABG) surgery to percutaneous transluminal coronary intervention, there has been an increase in the number of complex CABG surgical procedures performed, e.g. CABG with mixed valve replacement. This, combined with an ageing patient population with associated increased co-morbidities and risk factors, may lead to a rise in the incidence of ischaemic bowel in patients following CPB surgery [3]. Furthermore, definitive radiological diagnosis is known to be difficult in such patients [7]. The most common CT findings lack specificity, whereas the more specific findings are rarely present [8], thus knowledge of such CT findings and their diagnostic value would be beneficial.Mesenteric angiography was previously considered the gold standard radiological test for the diagnosis of mesenteric ischaemia of any aetiology. Although this offers the additional benefit of treatment in certain cases [9], the technique is invasive, availability may be limited in the acute setting, and it may be challenging in unstable post-operative patients [10]. CT overcomes some of these issues and provides additional diagnostic information about the bowel wall, solid intra-abdominal organs and vessel walls. In our selected patient group, non-occlusive mesenteric ischaemia owing to hypoperfusion associated with a low cardiac output postoperatively would be expected to be more prevalent than occlusive ischaemia [11,12].There have been several studies with a small number of patients looking at the multidetector CT features of patients presenting with mesenteric ischaemia [7,9,13–15], but to our knowledge, apart from a small case series [16], there are no studies specifically investigating the CT signs of bowel ischaemia in a post-cardiac surgery cohort. Thus, the aim of our study was to investigate the CT findings following pathologically proven mesenteric ischaemia/infarction in a retrospective group of patients postcardiac bypass surgery and compare this with the known features of acute mesenteric ischaemia.     

Pulmonary tuberculosis associated with the reversed halo sign on high-resolution CT

We describe the case of a 32-year-old woman with pulmonary tuberculosis in whom a high-resolution CT scan demonstrated the reversed halo sign. The diagnosis of tuberculosis was made by lung biopsy and the detection of acid-fast bacilli in the sputum smear and culture. Follow-up assessment revealed a significant improvement in the lesions.The reversed halo sign is observed on high-resolution CT (HRCT) as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation [1, 2]. It was first described as being relatively specific for cryptogenic organising pneumonia [1], but was later observed in several other infectious [3–5] and non-infectious [6, 7] diseases.We report a case of a 32-year-old patient with tuberculosis who exhibited the reversed halo sign on chest CT. To our knowledge, this sign has not been previously described in an adult with pulmonary tuberculosis.     

Calcifying cystic odontogenic tumour: CT imaging

Objectives

Calcifying cystic odontogenic tumour (CCOT) is a rare disorder of the jaw. A comparison between conventional radiographs and CT images in CCOTs has not been reported. The purposes of this study were to analyse conventional radiographs and CT images of CCOTs, establish CT images of CCOTs and assess the utility of CT in the diagnosis of CCOTs.

Methods

Nine patients with a histopathologically confirmed CCOT who had both conventional radiographs and CT images were enrolled.

Results

CT was superior to conventional radiographs in detecting buccolingual expansion, odontomas and radio-opaque bodies.

Conclusion

The characteristic CT appearances of CCOT were that radio-opaque bodies were typically located in the periphery of the lesion and the shape of radio-opaque bodies was linear and/or spotted. CT was useful in diagnosing a CCOT.The calcifying odontogenic cyst (COC) was first recognised as a distinct pathological entity by Gorlin et al [1] in 1962. COC is a rare disorder of the jaw [2], and the reported frequency of COCs varies from 0.37 to 2.1% of all odontogenic tumours [3]. In 2005, COC was classified as a tumour and designated as a “calcifying cystic odontogenic tumour” (CCOT) by the World Health Organization (WHO) [4].Histopathologically, the cyst wall is lined by a thin ameloblastomatous epithelium with the formation of ghost cells. These ghost cells may calcify [4], and the frequency of calcification in some of the ghost cells varies from 19 to 77% [5].Radiographically, a CCOT generally appears as a unilocular lesion with a well-defined margin and contains calcification [3]. Few studies have reported on the radiographic features of CCOTs in the English language literature [3,6], although CT image findings of CCOTs have been described [2,3,7]. A comparison between conventional radiographs and CT image findings in CCOTs, however, has not been reported.The purposes of this study were to analyse conventional radiographs and CT images of CCOTs, establish CT images of CCOTs and assess the utility of CT in the diagnosis of CCOTs.     

Comparative assessment of three image reconstruction techniques for image quality and radiation dose in patients undergoing abdominopelvic multidetector CT examinations

Objective

To compare image quality and radiation dose of abdominal CT examinations reconstructed with three image reconstruction techniques.

Methods

In this Institutional Review Board-approved study, contrast-enhanced (CE) abdominopelvic CT scans from 23 patients were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASiR) and iterative reconstruction in image space (IRIS) and were reviewed by two blinded readers. Subjective (acceptability, sharpness, noise and artefacts) and objective (noise) measures of image quality were recorded for each image data set. Radiation doses in CT dose index (CTDI) dose–length product were also calculated for each examination type and compared. Imaging parameters were compared using the Wilcoxon signed rank test and a paired t-test.

Results

All 69 CECT examinations were of diagnostic quality and similar for overall acceptability (mean grade for ASiR, 3.9±0.3; p=0.2 for Readers 1 and 2; IRIS, 3.9±0.4, p=0.2; FBP, 3.8±0.9). Objective noise was considerably lower with both iterative techniques (p<0.0001 and 0.0016 for ASiR and IRIS). Recorded mean radiation dose, i.e. CTDI_vol, was 24% and 10% less with ASiR (11.4±3.4 mGy; p<0.001) and IRIS (13.5±3.7 mGy; p=0.06), respectively, than with FBP: 15.0±3.5 mGy.

Conclusion

At the system parameters used in this study, abdominal CT scans reconstructed with ASiR and IRIS provide diagnostic images with reduced image noise and 10–24% lower radiation dose than FBP.

Advances in knowledge

CT images reconstructed with FBP are frequently noisy on lowering the radiation dose. Newer iterative reconstruction techniques have different approaches to produce images with less noise; ASiR and IRIS provide diagnostic abdominal CT images with reduced image noise and radiation dose compared with FBP. This has been documented in this study.CT continues to expand its role as an essential imaging modality [1]. However, with its increasing use, concerns of radiation overexposure have prompted efforts to reduce the cumulative dose to a patient [2]. Recent studies have highlighted increased utilisation of radiological examination and 10-fold increase in medical radiation exposure at the population level [3,4]. Therefore, lowering the CT radiation dose without compromising the image quality is desirable. Several technical approaches have been proposed to accomplish these goals including commonly used tube current modulation and adopting lower peak kilovoltage [5-8]. However, excessive dose reduction has remained difficult in the abdomen and pelvis CT due to increased levels of image noise and artefacts that lower the quality of the CT examination. Moreover, abdominopelvic CT demands higher image quality for confident detection of low-contrast lesions in various viscera [9]. The conventional technique of image reconstruction, filtered back projection (FBP), is an efficient method for image production, but makes several assumptions and therefore requires higher dose for delivering diagnostic quality images [10,11]. To overcome these limitations, iterative reconstruction (IR) techniques have been introduced, which have been shown to render optimal image quality at lower radiation dose [12-20]. Unlike advanced iterative techniques, partial IR approaches such as adaptive statistical iterative reconstruction (ASiR) and iterative reconstruction in image space (IRIS) are computationally less demanding and therefore faster to process images. In essence, both rely on mathematic modelling of the CT raw data to selectively identify image noise and reduce it. The ASiR technique models statistical variations in the distribution of noise from acquired image data and improves the signal-to-noise ratio while preserving image contrast [5,8,12]. Since its introduction, several investigators have confirmed its capabilities to deliver diagnostic quality images at 30–50% lower radiation dose. [8,12]. IRIS, on the other hand, reduces image noise by forming multiple iterations within the image space itself [10-14]. Phantom studies have demonstrated its ability in maintaining transverse and z-axis spatial resolution, as well as CT number accuracy and linearity while reducing image noise [18]. Its capability in preserving diagnostic accuracy and improving image quality at lower tube potential settings has been documented by Schindera et al [18] as has its ability to reduce noise and radiation dose in clinical studies by approximately 35–50% [11-16]. Owing to differences in image reconstruction approach by ASiR and IRIS, we investigated the performance of these two IR methods on image quality and radiation dose in patients undergoing contrast-enhanced (CE) abdominal CT examinations compared with the FBP technique.