Overnight Emergency CT Imaging: A 10-Year Experience at an Irish Tertiary Referral Hospital.

In recent years there has been increased utilisation of computed tomography (CT) imaging in developed countries, however there is a paucity of data regarding the utilisation of CT in the emergency overnight setting. We retrospectively analysed trends in 'overnight' (midnight to 8am) CT utilisation over a ten-year period at a single Irish tertiary referral hospital. Over the study period, we observed a significant increase in the proportion of CT imaging that was carried out overnight. There was no significant variation in the yield of pathological findings over the study period, which remained low (64% of CT studies were normal or had non-critical findings). The multiple factors which have contributed to the increased utilization of overnight emergency CT in recent years, the potential for reporting errors overnight and the implications therein for patient safety warrant consideration.

Accuracy of 64-section MDCT in the diagnosis of cruciate ligament tears.

AIM: To evaluate the accuracy of non-arthrographic 64-section multidetector computed tomography (CT) in the assessment of cruciate ligament tears. A secondary goal was to determine its accuracy in the diagnosis of additional soft-tissue injuries around the knee. MATERIALS AND METHODS: Forty consecutive outpatients underwent same-day magnetic resonance imaging (MRI) and 64-slice multidetector CT (MDCT) of the knee in this prospective study. MDCT images were independently evaluated for integrity of the anterior (ACL) and posterior cruciate ligaments (PCL), medial and lateral menisci, and medial and lateral collateral ligaments. Recognised secondary signs of ACL tears were also documented. MRI images were subsequently assessed by two radiologists and a consensus reached. RESULTS: The sensitivity of MDCT for ACL tears was 87.5-100%, with a specificity of 100%. The presence of one or more secondary signs of ACL tears on MDCT had a sensitivity of 50-87.5% with a specificity of 100%. The sensitivity of MDCT for PCL tears was 0-25% with a specificity of 100%. The sensitivity for meniscal tears was 9.1-23.1% with a specificity of 96.3-100%. CONCLUSION: 64-section MDCT has very high sensitivity and specificity for ACL tears and, as on MRI, secondary signs, such as buckling of the PCL, are also useful in their diagnosis. MDCT has a low sensitivity for other soft-tissue injuries at the knee; however, its high specificity indicates that apparent PCL, meniscal, and collateral ligament tears can reliably be treated as true-positive findings.

Ireland's recent contribution to the radiological literature; a bibliometric analysis.

The aim of this study was to identify and analyse all articles published by Irish radiology departments in the medical literature since the year 2000. The PubMed database was searched to identify and review all articles published by radiologists based in the Republic of Ireland or Northern Ireland. Citation counts were then obtained and the top ten most cited articles were identified. There were 781 articles published during the study period. Of these, 558 (71%) were published in radiology journals and the remaining 223 (29%) were published in general medical journals. Abdominal radiology was the most represented sub-specialty (33% of all articles). There was a general trend of increased publications per year. Only 75 (9.6%) of articles were collaborative efforts by more than one radiology department. Irish radiology departments have a considerable research output and this has increased since the year 2000. More collaborative research between Irish radiology departments is encouraged.

Is diffusion-weighted MRI sufficient for follow-up of neuroendocrine tumour liver metastases?

AIM: To assess if diffusion-weighted imaging (DWI) alone could be used for follow-up of neuroendocrine hepatic metastases. MATERIAL AND METHODS: This was a retrospective study, approved by the institutional review board. Twenty-two patients with neuroendocrine liver metastases who had undergone more than one liver magnetic resonance imaging (MRI) examination, (including DWI and using hepatocyte-specific contrast medium) were evaluated. Up to five metastases were measured at baseline and at each subsequent examination. The reference standard measurement was performed on the hepatocyte phase by one reader. Three independent readers separately measured the same lesions on DWI sequences alone, blinded to other sequences, and recorded the presence of any new lesions. RESULTS: The longest diameters of 317 liver metastases (91 on 22 baseline examinations and a further 226 measurements on follow-up) were measured on the reference standard by one reader and on three b-values by three other readers. The mean difference between DWI measurements and the reference standard measurement was between 0.01-0.08 cm over the nine reader/b-value combinations. Based on the width of the Bland and Altman interval containing approximately 95% of the differences between the reader observation and the mean of reference standard and DWI measurement, the narrowest interval over the nine reader/b-value combinations was -0.6 to +0.7 cm and the widest was -0.9 to 1 cm. In the evaluation of overall response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria, the weighted kappa statistic was between 0.49 and 0.86, indicating moderate-to-good agreement between the reference standard and DWI. CONCLUSION: The visualisation and measurement of hepatic metastases using DWI alone are within acceptable limits for clinical use, allowing the use of this rapid technique to restage hepatic disease in patients with neuroendocrine metastases.

Pathological fracture of the clavicle causing subclavian pseudoaneurysm formation.

Pseudoaneurysm of the subclavian artery is a rare but serious condition generally occurring as a result of penetrating injury to the shoulder region, often iatrogenic. As well as the potential for distal ischaemia, this condition can result in compression of adjacent structures. Untreated it can lead to rupture with life-threatening haemorrhage. We describe the unusual case of a patient with a background of metastatic breast carcinoma who presented with a pseudoaneurysm of the subclavian artery secondary to a pathological fracture of the clavicle. The patient was managed surgically due to the development of necrosis of the overlying skin. Less invasive management of subclavian pseudoaneurysms has recently been described, including endovascular stenting and percutaneous thrombin injection.

Mechanism of resistance to complement-mediated killing of bacteria encoded by the Salmonella typhimurium virulence plasmid gene rck.

We find that pADEO16, a recombinant cosmid carrying the rck gene of the Salmonella typhimurium virulence plasmid, when cloned into either rough or smooth Escherichia coli and Salmonella strains, confers high level resistance to the bactericidal activity of pooled normal human serum. The rck gene encodes a 17-kD outer membrane protein that is homologous to a family of virulence-associated outer membrane proteins, including pagC and Ail. Complement depletion, C3 and C5 binding, and membrane-bound C3 cleavage products are similar in strains with and without rck. Although a large difference in C9 binding was not seen, trypsin cleaved 55.7% of bound 125I-C9 counts from rough S. typhimurium with pADEO16, whereas only 26.4% were released from S. typhimurium with K2011, containing a mutation in rck. The majority of C9 extracted from rck strain membranes sediments at a lower molecular weight than in strains without rck, suggesting less C9 polymerization. Furthermore, SDS-PAGE analysis of gradient peak fractions indicated that the slower sedimenting C9-containing complexes in rck strains did not contain polymerized C9 typical of the tubular membrane attack complex. These results indicate that complement resistance mediated by Rck is associated with a failure to form fully polymerized tubular membrane attack complexes.

A comparative analysis of the occupational energy expenditure of radiologists versus clinicians.

BACKGROUND: Sedentary lifestyles have been associated with increased morbidity and mortality. Radiology as a profession may be sedentary compared to some clinical disciplines. AIM: Our aim was to measure the occupation-related energy expenditure of a cohort of radiologists versus clinicians using a specialized pedometer. METHODS: 25 radiologists and 25 clinicians (15 surgeons, 8 physicians and 2 emergency physicians) were measured. The amount of steps walked, stairs climbed and calories burned on a given day from 9 a.m. to 5 p.m. were compared between the groups. RESULTS: The difference in mean calorie usage per day was 320 greater, and steps walked per day 2,985 greater, in clinicians than in radiologists (p < 0.0001 for each). CONCLUSION: Such a difference in calorie intake can have significant long-term health implications in terms of increased weight or BMI. Means of combating this deficit are discussed.

Toxic shock syndrome: case report of a postpartum female and a literature review.

Toxic shock syndrome is one of the best understood of the systemic inflammatory response syndromes. The mechanisms of disease have been extensively studied; however, no therapies have been developed that can effectively reverse the syndrome once the inflammatory response has begun. Although toxic shock syndrome classically has been associated with tampon use, multiple other etiologies exist including postpartum toxic shock, which usually affects patients in the immediate weeks following delivery. We present a case of toxic shock in a woman 10 weeks postpartum and review the literature regarding both menstrual-related and nonmenstrual-related toxic shock.

John Thomas sign--a memorable but misleading sign in hip fractures.

OBJECTIVE: The John Thomas sign is a favourite of medical students and theorizes that in femoral neck fractures, the male member will lie to the side of the fracture on the plain radiograph. The aim of this study was to evaluate the accuracy, and examine the phenomenon of eponymous signs. We sought to answer the following questions: (1) How accurate is the sign in the context of a consecutive series of male patients with hip fractures? (2) Is there a relationship between side and size of penile lie and the side of fracture? HYPOTHESIS: That the accuracy of the John Thomas sign is, like many eponymous signs, spurious. MATERIALS AND METHODS: Two hundred male AP pelvis radiographs were examined, of which 100 had a hip fracture and compared these against 100 control films that did not. Age at presentation, and the side, length and angle of penile lie were measured. RESULTS: The results show two findings: that the accuracy of the supposed "sign" is less accurate than the toss of a coin; and that left lie and left-sided fractures are more common. We fail to show a relationship between side of fracture, John Thomas size or degree of angulation. CONCLUSION: John Thomas sign is no better than the toss of a coin in relation to hip fractures, and is not related to side of fracture, or penile attitude. We propose that the side of lie observed in male fractures may be as a result of handedness or natural underlying body asymmetry rather than as a result of the fracture. LEVEL OF EVIDENCE: Level III Case control study.

Pancreaticoduodenectomy: expected post-operative anatomy and complications.

Pancreaticoduodenectomy is a complex, high-risk surgical procedure performed for tumours of the pancreatic head and other periampullary structures. The rate of perioperative mortality has decreased in the past number of years but perioperative morbidity remains high. This pictorial review illustrates expected findings in early and late post-operative periods, including mimickers of pathology. It aims to familiarize radiologists with the imaging appearances of common and unusual post-operative complications. These are classified into early non-vascular complications such as delayed gastric emptying, post-operative collections, pancreatic fistulae and bilomas; late non-vascular complications, for example, biliary strictures and hepatic abscesses; and vascular complications including haemorrhage and ischaemia. Options for minimally invasive image-guided management of vascular and non-vascular complications are discussed. Familiarity with normal anatomic findings is essential in order to distinguish expected post-operative change from surgical complications or recurrent disease. This review summarizes the normal and abnormal radiological findings following pancreaticoduodenectomy.

Aggressive angiomyxoma of the thigh.

Aggressive angiomyxoma is a rare tumour that typically occurs in the perineum in women of reproductive age. A small number of cases occurring in men have been reported, all of which were located in the low pelvis, perineum or scrotum. While benign, the tumour is locally infiltrative and consequently has a high rate of local recurrence following surgery; therefore, accurate pre-operative diagnosis is important. The characteristic location of these tumours in the low pelvis or perineum has led to speculation that aggressive angiomyxomas arise from a mesenchymal cell that is unique to the perineum. We describe a case of aggressive angiomyxoma arising in the thigh of a 54-year-old man, which we believe is the first reported instance of this rare neoplasm occurring remote from the pelvis or perineum in a male patient. Cross-sectional imaging demonstrated a well-defined mass that had low density on CT and high intensity on fluid-sensitive MR sequences. Biopsy was non-diagnostic and excision was performed. At histological analysis, the tumour exhibited the characteristic features of aggressive angiomyxoma, with bland spindle cells and large, hyalinised blood vessels in a hypocellular myxoid matrix. Extensive immunohistochemical staining further supported the diagnosis. While the imaging features of these tumours are non-specific and suggestive of myxoid neoplasms, the diagnosis should be considered whenever biopsy of a myxoid-appearing mass yields hypocellular, non-diagnostic material, despite adequate sampling.

Ossifying lipoma of the thigh.

Lipomas are common soft-tissue tumours that are usually found in the subcutaneous adipose tissue. Occasionally, they may contain mesenchymal elements other than adipose tissue, including osseous components. These ossifying lipomas are usually located near or within bone, and it is very rare for a lipoma with no connection to bone to contain mature osseous tissue. We describe a case of a symptomatic ossifying intramuscular lipoma of the thigh.

The imaging appearances of metallosis.

Metallosis is an uncommon condition in which there is infiltration of periprosthetic soft tissues and bone by metallic debris resulting from wear of joint arthroplasties. It is often associated with significant osteolysis; therefore the identification of metallosis is an indication for revision arthroplasty. The radiographic, CT and MRI features of metallosis in a 63-year-old man who presented 16 years post-arthroplasty are described in this case report.

Natural history of oral Salmonella dublin infection in BALB/c mice: effect of an 80-kilobase-pair plasmid on virulence.

BALB/c mice were infected orally with Salmonella dublin strains Lane and LD842, an isogenic derivative of the former that is avirulent because it was cured of its 80-kilobase-pair virulence plasmid pSDL2. Both strains colonized the intestine and invaded Peyer's patches with equivalent efficiency. However, the parent strain multiplied in mesenteric nodes and in the spleen; the plasmid-cured strain reached these organs, but the infection was low grade and remained relatively static until the mice developed active immunity and cured themselves. The histological response to plasmid-free strain LD842 was mononuclear, whereas the virulent parent strain produced abscesses. Sublethal irradiation of the mice before infection with strain LD842 prevented the mononuclear infiltrate in the liver and made the animals susceptible. Thus the virulence plasmid of S. dublin allows multiplication within the reticuloendothelial system and does not have any effect on the organism's ability to colonize the intestine or invade Peyer's patches.

The Salmonella typhimurium virulence plasmid complement resistance gene rck is homologous to a family of virulence-related outer membrane protein genes, including pagC and ail.

A fragment of the Salmonella typhimurium virulence plasmid containing the rck locus, when cloned in the recombinant cosmid pADE016, was shown previously to confer high-level complement resistance on both rough and smooth Escherichia coli, Salmonella minnesota, and S. typhimurium and was associated with the production of an outer membrane protein. We determined the nucleotide sequence of the fragment containing the rck locus. Mutations in the two major open reading frames confirmed that the complement resistance mediated by pADE016 was due to a single 555-bp rck gene encoding a 17-kDa outer membrane protein. Analysis of the rck gene revealed that the Rck outer membrane protein consisted of 185 amino acid residues, with a calculated postcleavage molecular mass of 17.4 kDa. Rck is homologous to a family of outer membrane proteins expressed in gram-negative bacteria, two of which have been associated with virulence-related phenotypes: PagC, required by S. typhimurium for survival in macrophages and for virulence in mice; and Ail, a product of the Yersinia enterocolitica chromosome capable of mediating bacterial adherence to and invasion of epithelial cell lines. Rck, most closely related to PagC, represents the third outer membrane protein in this five-member family with a distinct virulence-associated phenotype.

Specificity of the complement resistance and cell association phenotypes encoded by the outer membrane protein genes rck from Salmonella typhimurium and ail from Yersinia enterocolitica.

Virulence-associated phenotypes of an outer membrane protein gene family of members of the family Enterobacteriaceae were compared by means of pBR322 constructs transformed into Escherichia coli HB101.rck (Salmonella typhimurium) and ail (Yersinia enterocolitica) promote serum resistance and eukaryotic cell invasion, properties not shared by other members of the gene family, pagC, ompX, and lom.

Identification of a domain in Rck, a product of the Salmonella typhimurium virulence plasmid, required for both serum resistance and cell invasion.

Rck is encoded on the Salmonella typhimurium virulence plasmid and is a member of a family of related 17- to 19-kDa outer membrane proteins of Enterobacteriaceae, including Ail (Yersinia enterocolitica) and PagC (S. typhimurium). Structural models for these proteins predict eight membrane-spanning domains alternating with hydrophilic inner and outer loops. When expressed in Escherichia coli, Rck and Ail, but not PagC, confer high-level resistance to the bactericidal activity of complement as well as the ability to adhere to and invade mammalian cell lines. To identify functional domains of Rck, we made and screened random mutations in Rck for decreased bioactivity. We found that a single amino acid substitution (glycine to aspartic acid) in the putative third outer loop greatly reduced Rck-mediated serum resistance and eukaryotic cell invasion. We then constructed two chimeric proteins between Rck and PagC. Substitution of the C-terminal half of Rck with the corresponding PagC fragment containing both the third and the fourth outer loops abolishes the Rck-mediated serum resistance and invasion phenotypes. Substitution of Rck with a smaller C-terminal portion of PagC containing the fourth outer loop did not affect the invasive phenotype or serum resistance. These data reveal that the third putative outer membrane loop region is important for the virulence-associated properties of the Rck protein and suggest a similarity between the mechanism of serum resistance and epithelial cell invasion involving the same domain of Rck.