Multi-detector computed tomography of acute abdomen

Selection of density standard and X-ray tube settings for computed digital absorptiometry in horses using the k-means clustering algorithm

BACKGROUND

In veterinary medicine, conventional radiography is the first-choice method for most diagnostic imaging applications in both small animal and equine practice. One direction in its development is the integration of bone density evaluation and artificial intelligence-assisted clinical decision-making, which is expected to enhance and streamline veterinarians' daily practices. One such decision-support method is k-means clustering, a machine learning and data mining technique that can be used clinically to classify radiographic signs into healthy or affected clusters. The study aims to investigate whether the k-means clustering algorithm can differentiate cortical and trabecular bone in both healthy and affected horse limbs. Therefore, identifying the optimal computed digital absorptiometry parameters was necessary.

METHODS AND RESULTS

Five metal-made density standards, made of pure aluminum, aluminum alloy (duralumin), cuprum alloy, iron-nickel alloy, and iron-silicon alloy, and ten X-ray tube settings were evaluated for the radiographic imaging of equine distal limbs, including six healthy limbs and six with radiographic signs of osteoarthritis. Density standards were imaged using ten combinations of X-ray tube settings, ranging from 50 to 90 kV and 1.2 to 4.0 mAs. The relative density in Hounsfield units was firstly returned for both bone types and density standards, then compared, and finally used for clustering. In both healthy and osteoarthritis-affected limbs, the relative density of the long pastern bone (the proximal phalanx) differed between bone types, allowing the k-means clustering algorithm to successful differentiate cortical and trabecular bone.

CONCLUSION

Density standard made of duralumin, along with the 60 kV, 4.0 mAs X-ray tube settings, yielded the highest clustering metric values and was therefore considered optimal for further research. We believe that the identified optimal computed digital absorptiometry parameters may be recommended for further researches on the relative quantification of conventional radiographs and for distal limb examination in equine veterinary practice.

A Novel Diagnostic Imaging Method for the Early Detection of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, with a survival rate of less than 10% [...].

The added value of multidetector CT in the diagnosis of gastrointestinal causes of acute abdomen in geriatrics

Background

Due to changes in the gastrointestinal system in geriatric people, there are higher rates of atypical presentations of common disorders. In order to decrease the mortality rate, an efficient and correct diagnosis should be given for these patients. The aim of this study was to assess the role of MDCT in evaluating gastrointestinal tract-related acute abdominal pain in geriatric patients.

Results

Among fifty geriatric patients presented clinically with acute abdominal pain of gastrointestinal origin from November 2019 to September 2020, mean age was 70.2 ± 5.6 years ranging from 65 to 86 years. Majority were female, (thirty patients, 60%). Gastric causes (16%): obstruction (62.5%) and perforation (37.5%); and intestinal causes (84%): obstruction (71.4%), inflammatory (28.6%), perforation (23.8%), vascular (11.9%), and others (2.4%) were the frequent causes of acute abdominal pain in the studied patients. MDCT had a very high sensitivity of 98% (95% CI) as well as its PPV (95% CI) was 100% in the evaluation of gastrointestinal-related acute abdominal pain.

Conclusion

MDCT is a reliable diagnostic imaging modality for geriatric patients presented with acute abdominal pain suggested to be of gastrointestinal origin with a very high sensitivity in diagnosing the causative pathological conditions. MDCT can efficiently differentiate between obstructive, inflammatory, perforated, and ischemic bowel disorders.

Surgeon-performed ultrasound for the staging of acute diverticulitis: Preliminary results of a prospective study

INTRODUCTION

Although contrast-enhanced abdominal computed tomography (CEACT) is still considered the criterion standard for the assessment of suspected acute diverticulitis, in recent years, the use of point-of-care ultrasound (POCUS) has been spreading more and more in this setting. The aim of this study was to compare CEACT to POCUS for the diagnosis and staging of suspected acute diverticulitis.

METHODS

This is a prospective study conducted on 55 patients admitted to the emergency department of two Italian Hospitals with a clinical suspicion of acute diverticulitis between January 2014 and December 2017. All the patients included underwent POCUS first and CEACT immediately afterward, with the diagnosis and the staging reported according to the Hinchey (H) classification modified by Wasvary et al. [Wasvary H, Turfah F, Kadro O, Beauregard W. Same hospitalization resection for acute diverticulitis. Am Surg. 1999;65:632-635.] Three surgeons performed all the POCUS, and the same two radiologists retrospectively analyzed all the CEACT images. The radiologists were informed of the clinical suspicion but unaware of the POCUS findings. The CEACT was used as the criterion standard for the comparison.

RESULTS

The final cohort included 30 females (55%) and 25 males (45%). The median age was 62 years (range, 24-88 years), and the median body mass index was 26 kg/m2 (range, 19-42 kg/m2). Forty-six of 55 patients had a confirmed diagnosis of acute diverticulitis on both POCUS and CEACT, whereas, in 7 patients, the diagnosis was not confirmed by both methods. Point-of-care ultrasound sensitivity and specificity were 98% and 88%, respectively. Point-of-care ultrasound positive and negative predictive values were 98% and 88%, respectively. Point-of-care ultrasound accuracy was 96%. Point-of-care ultrasound classified 33 H1a, 11 H1b, 1 H2, and 1 H3 acute diverticulitis. This staging was confirmed in all patients but three (93%) by CEACT.

CONCLUSION

Point-of-care ultrasound appeared a reliable technique for the diagnosis and the staging of clinically suspected H1 and H2 acute diverticulitis. It could contribute in saving time and resources and in avoiding unnecessary radiation exposure to most patients.

LEVEL OF EVIDENCE

Diagnostic test, level III.

A case of perforation of Meckel's diverticulum with enterolith

Background

Perforation of Meckel’s diverticulum with enteroliths is a rare complication. Here, we report a case of perforation of Meckel’s diverticulum with one enterolith, which could not be accurately diagnosed by preoperative computed tomography.

Case presentation

A 16-year-old male patient with acute onset of severe abdominal pain and a localized muscle guarding in the right hypochondrium had a solitary stone detected in the right abdomen by radiography. Abdominal computed tomography revealed a saclike outpouching of the small intestine, which contained fluid levels and an enterolith, with a mesenteric inflammatory change in the right paraumbilical area. He was diagnosed with peritonitis due to appendicitis or Meckel’s diverticulitis with enterolith, and emergency operation was indicated. The perforated Meckel’s diverticulum was identified approximately 30 cm proximal to the ileocecal valve. The diverticulum was transected at the base and removed. The patient’s postoperative course was uneventful.

Conclusions

It is crucial for clinicians to thoroughly examine patients and appropriately request investigations that consider perforation of Meckel’s diverticulum as a possible diagnosis to facilitate prompt treatment.

Perforated Meckel's Diverticulum in an Adult

Meckel's diverticulum is the commonest congenital anomaly of the gastrointestinal tract. Its complications have an extensive variety of clinical and imaging manifestations, extending from benign and indolent findings to acute life-threatening conditions. Complicated Meckel's diverticulum often constitutes a challenging diagnosis for both the clinician and the radiologist. Therefore, imaging techniques play an important role in this condition in evaluating its complications, determining decision making. We describe a case of a 49-year-old man suffering from right abdominal pain with fever and constipation, during the past 5 days. Laboratory data revealed C-reactive protein of 306 mg/L and leukocytosis. Contrast-enhanced CT features were highly suggestive of perforated Meckel's diverticulum. The purpose of this article is to emphasize that besides its rarity, Meckel's diverticulum complications can occur in adult patients.

Discrepancies in interpretation of night-time emergency computed tomography scans by radiology residents

Background

In many emergency radiology units, most of the night-time work is performed by radiology residents. Residents’ preliminary reports are typically reviewed by an attending radiologist. Accordingly, it is known that discrepancies in these preliminary reports exist.

Purpose

To evaluate the quality of night-time computed tomography (CT) interpretations made by radiology residents in the emergency department.

Material and Methods

Retrospectively, 1463 initial night-time CT interpretations given by a radiology resident were compared to the subspecialist’s re-interpretation given the following weekday. All discrepancies were recorded and classified into different groups regarding their possible adverse effect for the emergency treatment. The rate of discrepancies was compared between more and less experienced residents and between different anatomical regions.

Results

The overall rate of misinterpretations was low. In 2.3% (33/1463) of all night-time CT interpretations, an important and clinically relevant diagnosis was missed. No fatalities occurred due to CT misinterpretations during the study. The total rate of discrepancies including clinically irrelevant findings such as anatomical variations was 12.2% (179/1463). Less experienced residents were more likely to miss the correct diagnosis than more experienced residents (18.3% vs. 10.9%, odds ratio [OR] = 1.82, P = 0.001). Discrepancies were more common in body CT interpretations than in neurological CTs (18.1% vs. 9.1%, OR = 2.30, P < 0.0001).

Conclusion

The rate of clinically important misinterpretations in CT examinations by radiology residents was found to be low. Experience helps in lowering the rate of misinterpretations.

Multiplanar Computed Tomography of Vascular Etiologies of Acute Abdomen: A Pictorial Review

Acute abdomen is a common presentation in the emergency department and radiologic imaging plays a pivotal role in the evaluation of such patients. Multi-detector computed tomography (MDCT) is the most commonly utilized radiologic investigation in such patients as it can be performed fairly rapidly and has excellent accuracy for diagnosing various causes of an acute abdomen. Additionally, MDCT may also reveal clues towards an alternative diagnosis that was not even suspected on the basis of a history and physical examination. Consequently, it is indispensable for radiologists to be able to accurately and efficiently recognize imaging features of disorders that may present as an acute abdomen. While gastrointestinal, hepatobiliary and genitourinary causes account for most cases of acute abdomen, vascular etiologies may also be implicated in a small-but significant-proportion of cases. Therefore, in this pictorial review, we describe the typical MDCT imaging features of various vascular etiologies that may present as an acute abdomen.

CT findings in acute peritonitis: a pattern-based approach

Many inflammatory and infectious entities may acutely affect the peritoneum causing a thickening of its layers. Unfortunately, several acute peritoneal diseases can have overlapping features, both clinically and at imaging. Therefore, the awareness of the clinical context, although useful, may be sometimes insufficient to identify the underlying cause. This article provides a specific computed tomography-based approach including morphologic characteristics of peritoneal thickening (e.g., smooth, irregular, or nodular) and ancillary findings to narrow the differential diagnosis of acute peritonitis.

Effect of reconstruction methods and x-ray tube current-time product on nodule detection in an anthropomorphic thorax phantom: A crossed-modality JAFROC observer study

Purpose:

To evaluate nodule detection in an anthropomorphic chest phantom in computed tomography (CT) images reconstructed with adaptive iterative dose reduction 3D (AIDR^3D) and filtered back projection (FBP) over a range of tube current–time product (mAs).

Methods:

Two phantoms were used in this study: (i) an anthropomorphic chest phantom was loaded with spherical simulated nodules of 5, 8, 10, and 12 mm in diameter and +100, −630, and −800 Hounsfield units electron density; this would generate CT images for the observer study; (ii) a whole-body dosimetry verification phantom was used to ultimately estimate effective dose and risk according to the model of the BEIR VII committee. Both phantoms were scanned over a mAs range (10, 20, 30, and 40), while all other acquisition parameters remained constant. Images were reconstructed with both AIDR^3D and FBP. For the observer study, 34 normal cases (no nodules) and 34 abnormal cases (containing 1–3 nodules, mean 1.35 ± 0.54) were chosen. Eleven observers evaluated images from all mAs and reconstruction methods under the free-response paradigm. A crossed-modality jackknife alternative free-response operating characteristic (JAFROC) analysis method was developed for data analysis, averaging data over the two factors influencing nodule detection in this study: mAs and image reconstruction (AIDR^3D or FBP). A Bonferroni correction was applied and the threshold for declaring significance was set at 0.025 to maintain the overall probability of Type I error at α = 0.05. Contrast-to-noise (CNR) was also measured for all nodules and evaluated by a linear least squares analysis.

Results:

For random-reader fixed-case crossed-modality JAFROC analysis, there was no significant difference in nodule detection between AIDR^3D and FBP when data were averaged over mAs [F(1, 10) = 0.08, p = 0.789]. However, when data were averaged over reconstruction methods, a significant difference was seen between multiple pairs of mAs settings [F(3, 30) = 15.96, p < 0.001]. Measurements of effective dose and effective risk showed the expected linear dependence on mAs. Nodule CNR was statistically higher for simulated nodules on images reconstructed with AIDR^3D (p < 0.001).

Conclusions:

No significant difference in nodule detection performance was demonstrated between images reconstructed with FBP and AIDR^3D. mAs was found to influence nodule detection, though further work is required for dose optimization.

Evaluating Patients with Left Upper Quadrant Pain

Imaging plays a major role in the evaluation of patients who present to the emergency department with acute left upper quadrant (LUQ) pain. Multidetector computed tomography is currently the primary modality used for imaging these patients. The peritoneal reflections, subperitoneal compartment, and peritoneal spaces of the LUQ are key anatomic features in understanding the imaging appearance of acute diseases in this area. Diseases of the stomach, spleen, pancreas, and splenic flexure are encountered in patients with acute LUQ pain. Optimization of the imaging protocol is vital for accurate diagnosis and characterization of these diseases in the acute setting.

Acute abdominal pain in childhood and adolescence: assessing the impact of sonography on diagnosis and treatment

PURPOSE

To assess the impact of ultrasonography on defining the diagnostic and therapeutic pathways for pediatric patients admitted to the emergency department for acute abdominal pain.

METHODS

We performed a retrospective study of all patients aged <16 years with acute abdominal pain who underwent ultrasound examination at our Diagnostic Imaging Department from October 2010 to March 2012. We investigated for each patient the pathway following ultrasound examination and definitive diagnosis. The impact of ultrasonography was defined based on the frequency with which the information resulting from this examination confirmed or denied the diagnostic suspicion made by the emergency physician on the basis of clinical and laboratory findings.

RESULTS

In 497/729 patients (69 %), ultrasound examination did not determine variations in the diagnostic and therapeutic pathways, either because it confirmed the outcome of clinical examination and laboratory tests, or because, even addressing in the opposite direction to these, the emergency physician did not consider its result because of being particularly alarmed or sufficiently reassured by clinical examination and laboratory tests. In the remaining 232/729 cases (31 %), ultrasound examination determined an increase or a reduction of the provided care and attention (subsequently proved justified in the vast majority of cases) in spite of what was initially assessed based on clinical examination and laboratory tests.

CONCLUSIONS

The results of our retrospective study demonstrated that ultrasonography was a valuable tool in the management of pediatric patients with acute abdominal pain together with clinical examination and laboratory tests.

Accuracy of 64-row multidetector CT in the diagnosis of surgically treated acute abdomen

OBJECTIVE

To assess the accuracy of 64-row computed tomography (CT) in the differential diagnosis of acute abdomen in the emergency department.

MATERIALS AND METHODS

Prospective analysis of 181 patients with surgically treated acute abdomen.

RESULTS

In 158/181 cases, CT was totally concordant with surgical repertoire. Partial concordance was found in 15 cases. Overall sensitivity was 87.3% when only cases of complete concordance were considered, 95.6% if also partial concordance cases were included.

CONCLUSION

CT showed high reliability in the differential diagnosis of acute abdomen surgically treated, although associated conditions can sometimes be missed.

An evolutionary role of the ED: outcomes of patients with colorectal cancers presenting to the ED were not compromised

PURPOSE

Patients with colorectal cancer (CRC) who present to the emergency department (ED) reportedly have poorer prognoses than other referral sources. The purpose of this study was to compare the clinical presentations and outcomes of patients referred to the hospital from the ED and those referred from non-ED facilities.

METHODS

This retrospective medical record review study was conducted from January 1, 2008, to December 31, 2008, and comprised patients newly diagnosed as having CRC admitted to the hospital from the ED or referred from non-ED sources. Patients were admitted for CRC diagnosis confirmation, staging, and treatment. The staging at diagnosis and 2-year mortality were measured.

RESULTS

Forty-five (29.2%) patients comprised the ED group, and another 109 (70.8%) patients comprised the non-ED group. Patients in the ED group had significantly longer hospital stays, greater in-hospital mortality, abdominal pain, intestinal obstruction, complications, lower hemoglobin levels, and more proximal than rectosigmoid tumor locations compared with patients referred from other sources. However, there was no statistically significant difference in stage at diagnosis or 2-year mortality rate between the groups.

CONCLUSIONS

The ED played a pivotal role in the clinical and diagnostic evaluations of patients with CRC at our institution. Emergency department physicians provided timely diagnoses of CRC because the stage at diagnosis and 2-year mortality rate of ED patients were not compromised compared with that of patients referred from non-ED sources. Efforts should be made to reduce the numbers of patients with late presentations and acute complications associated with in-hospital mortality.

Mesenteric vascular occlusion: comparison of ancillary CT findings between arterial and venous occlusions and independent CT findings suggesting life-threatening events

OBJECTIVE

To compare the ancillary CT findings between superior mesenteric artery thromboembolism (SMAT) and superior mesenteric vein thrombosis (SMVT), and to determine the independent CT findings of life-threatening mesenteric occlusion.

MATERIALS AND METHODS

Our study was approved by the institution review board. We included 43 patients (21 SMAT and 22 SMVT between 1999 and 2008) of their median age of 60.0 years, and retrospectively analyzed their CT scans. Medical records were reviewed for demographics, management, surgical pathology diagnosis, and outcome. We compared CT findings between SMAT and SMVT groups. Multivariate analysis was conducted to determine the independent CT findings of life-threatening mesenteric occlusion.

RESULTS

Of 43 patients, 24 had life-threatening mesenteric occlusion. Death related to mesenteric occlusion was 32.6%. A thick bowel wall (p < 0.001), mesenteric edema (p < 0.001), and ascites (p = 0.009) were more frequently associated with SMVT, whereas diminished bowel enhancement (p = 0.003) and paralytic ileus (p = 0.039) were more frequent in SMAT. Diminished bowel enhancement (OR = 20; p = 0.007) and paralytic ileus (OR = 16; p = 0.033) were independent findings suggesting life-threatening mesenteric occlusion.

CONCLUSION

The ancillary CT findings occur with different frequencies in SMAT and SMVT. However, the independent findings indicating life-threatening mesenteric occlusion are diminished bowel wall enhancement and paralytic ileus.

Beyond appendicitis: common and uncommon gastrointestinal causes of right lower quadrant abdominal pain at multidetector CT

Right lower quadrant abdominal pain is one of the most common causes of a patient visit to the emergency department. Although appendicitis is the most common condition requiring surgery in patients with abdominal pain, right lower quadrant pain can be indicative of a vast list of differential diagnoses and is thus a challenge for clinicians. Other causes of right lower quadrant pain beyond appendicitis include inflammatory and infectious conditions involving the ileocecal region; diverticulitis; malignancies; conditions affecting the epiploic appendages, omentum, and mesentery; and miscellaneous conditions. Multidetector computed tomography (CT) has emerged as the modality of choice for evaluation of patients with several acute traumatic and nontraumatic conditions causing right lower quadrant pain. Multidetector CT is an extremely useful noninvasive method for diagnosis and management of not only the most common causes such as appendicitis but also less common conditions.

Standard outpatient re-evaluation for patients not admitted to the hospital after emergency department evaluation for acute abdominal pain

Background

The aim of the present study was to investigate the efficacy and safety of standard outpatient re-evaluation for patients who are not admitted to the hospital after emergency department surgical consultation for acute abdominal pain.

Methods

All patients seen at the emergency department between June 2005 and July 2006 for acute abdominal pain were included in a prospective study using a structured diagnosis and management flowchart. Patients not admitted to the hospital were given appointments for re-evaluation at the outpatient clinic within 24 h. All clinical parameters, radiological results, diagnostic considerations, and management proposals were scored prospectively.

Results

Five-hundred patients were included in this analysis. For 148 patients (30%), the final diagnosis was different from the diagnosis after initial evaluation. Eighty-five patients (17%) had a change in management after re-evaluation, and 20 of them (4%) were admitted to the hospital for an operation. Only 6 patients (1.2%) had a delay in diagnosis and treatment, which did not cause extra morbidity.

Conclusions

Standard outpatient re-evaluation is a safe and effective means of improving diagnostic accuracy and helps to adapt management for patients that are not admitted to the hospital after surgical consultation for acute abdominal pain at the emergency department.

Prediction and management of a low-lying costal arch which restricts the operative working space during laparoscopic cholecystectomy

BACKGROUND/PURPOSE

Laparoscopic cholecystectomy is difficult to perform in patients with a low-lying costal arch that entirely covers the liver. We conducted this study to clarify the factors related to a low-lying costal arch and establish countermeasures to circumvent this characteristic.

METHODS

The study included 103 consecutive patients who underwent a laparoscopic cholecystectomy. The possible clinical factors associated with a low-lying costal arch restricting the operative working space were analyzed. The position of the liver against the costal arch and the presumed surgical visual angle for laparoscopic cholecystectomy, comprising the hepatic porta, umbilicus, and costal arch, were estimated with abdominal multidetector computed tomography (MDCT).

RESULTS

Seven (7%) patients had a low-lying costal arch presenting an inadequate exposure of Calot's triangle and restricted instrument mobility during laparoscopic cholecystectomy, and three patients required conversion to a laparotomy. A low-lying costal arch was significantly associated with advanced age, shorter stature, lighter body weight, coexisting kyphoscoliosis, gallbladder pathology, laparotomy conversion, and most of all, the liver edge lying above the costal arch and a narrow surgical visual angle upon MDCT. Of the seven patients with a critical low-lying costal arch, four underwent a successful laparoscopic cholecystectomy, this being done by lifting the right costal arch to create a workable surgical field; the rib-lifting procedure was planned as part of the scheduled procedure in the other three patients because the preoperative MDCT examination indicated a poor working space for a laparoscopic cholecystectomy.

CONCLUSIONS

A low-lying costal arch is a substantial risk factor for conversion to a laparotomy when performing a laparoscopic cholecystectomy. However, the operative difficulty related to a low-lying costal arch can be predicted by using preoperative MDCT images and can be managed with proper planning and the appropriate use of the rib-lifting technique.

Computed tomography of complicated Meckel's diverticulum in adults: a pictorial review

OBJECTIVE: To show various CT aspects of complicated Meckel's diverticulum in adult patients to facilitate the preoperative diagnosis of this rare pathology in emergency settings. METHODS: A computer search of medical records over a 15 year period identified 23 adult patients who underwent surgery for acute abdomen generated by a complicated Meckel's diverticulum. CT images available for review were analyzed, and some specific patterns leading to the diagnosis of complicated Meckel's diverticulum are presented in this review. RESULTS: Complications were related to inflammation (14 patients), bleeding (5 patients), intestinal obstruction (3 patients), and penetrating foreign body (1 patient). The presence of a Meckel's diverticulum was usually suggested at CT scan by an abnormal outpouching, blind-ending digestive structure connected to the terminal ileum by a neck of variable caliber. Depending on the type of complications, the diverticulum was surrounded by mesenteric inflammatory changes, or presented as a localized fluid or air-fluid collection contiguous with the terminal ileum. The diverticulum was also the source of active bleeding or acted as the lead point to intestinal obstruction or intussusception. CONCLUSION: CT findings of complicated Meckel's diverticulum are polymorphic and should be considered in the evaluation of adult patients with acute abdomen.

Does cholecystectomy status influence the common bile duct diameter? A matched-pair analysis

The common bile duct (CBD) diameter is one factor that clinicians use when deciding on invasive evaluation for intra-ductal pathology, e.g., endoscopic retrograde cholangiopancreatography. Previous studies and gastrointestinal and radiological textbook authors report disparate interpretations. These inconsistent interpretations likely result from methodological limitations in prior studies. The purpose of this work is to primarily compare the CBD diameter among patients with and without prior cholecystectomy and secondarily to compare proximal and distal CBD measurements. Among 40 matched pairs, post-cholecystectomy patients had larger mean CBD diameters at proximal (7.0 vs. 5.4 mm; P < 0.001) and distal (5.9 vs. 4.6 mm; P < 0.001) sites. Post-cholecystectomy patients were also more likely to exceed the 6-mm cut point for proximal (80 vs. 28%; P < 0.001) or distal (58 vs. 20%; P = 0.003) measurements. Incidental radiographic detection of enlarged CBDs among post-cholecystectomy patients is common; therefore, clinicians should use clinical determinants to guide decisions about additional costly or potentially harmful evaluation for intraductal pathology.

CT findings of mild forms or early manifestations of acute cholecystitis

OBJECTIVE

The objective of this study was to determine the most predictive CT feature of the mild forms or early manifestations of acute cholecystitis.

MATERIALS AND METHODS

Two radiologists analyzed CT of 34 patients with mild or early acute cholecystitis and 34 control patients for pericholecystic increased attenuation on the arterial phase, indistinctness of the interface between the gallbladder (GB) and the liver, enhancement of the GB wall, and increased attenuation of the GB bile.

RESULTS

There were significant differences in the mean values for each CT feature but increased attenuation of the GB bile between patients and control group (P<.05). The most significant predictor of mild or early acute cholecystitis on CT was the presence of pericholecystic increased attenuation on the arterial phase (sensitivity, 82.4%), followed by indistinctness of the interface between the GB and liver (sensitivity, 38.0%), which were identified by both observers with good agreement (kappa=0.735 and kappa=0.687).

CONCLUSIONS

The pericholecystic increased attenuation on arterial phase CT was the most significant predictor of mild forms or early manifestations of acute cholecystitis.

The challenge of CT and MRI imaging of obese individuals who present to the emergency department: a national survey

The objective of this study was to estimate the availability of large weight capacity computed tomography (CT) and magnetic resonance imaging (MRI) equipment in US hospitals with emergency departments (EDs) and to evaluate animal facilities as alternate sources of imaging. We conducted a telephone survey of radiology technicians from a random sample of all the US hospitals with EDs (n = 262) and all 136 primary hospitals of academic EDs, 145 zoos, and 28 veterinary schools. We measured the prevalence of large weight capacity (>450 lb) CT and MRI, stratified by hospital characteristics. Response rates were 94-100% across samples. Nationally, 10% (95% confidence interval, 7-15) of hospitals with EDs had large weight capacity CT and 8% (95% confidence interval, 5-13) had large weight capacity MRI. In academic hospitals, access to large capacity equipment was better for CT (28%), but similar for MRI (10%) (P < 0.001 and 0.51, respectively). Few rural (5%) and critical-access hospitals (3%) had large capacity CT. In addition, 34% of trauma centers, 23% of stroke centers, and 21% of bariatric surgery centers of excellence had large capacity CT. Only two zoos (1%) had CT scanners; both would not image human patients. Among veterinary schools, 16 (57%) had large weight capacity CT equipment, but only 4 (14%) would consider imaging human patients. Further, 23 (82%) veterinary schools reported policies that specifically prohibited imaging humans. For patients who weigh >450 lb, access to emergent CT and MRI is limited, even at academic and bariatric surgery centers. Animal facilities are not a viable alternative for diagnostic imaging of human patients.

Availability and quality of computed tomography and magnetic resonance imaging equipment in U.S. emergency departments

OBJECTIVES

The objective was to determine the availability and quality of computed tomography (CT) and magnetic resonance imaging (MRI) equipment in U.S. emergency departments (EDs). The authors hypothesized that smaller, rural EDs have less availability and lower-quality equipment.

METHODS

This was a random selection of 262 (5%) U.S. EDs from the 2005 National Emergency Department Inventories (NEDI)-USA (http://www.emnet-usa.org/). The authors telephoned radiology technicians about the presence of CT and MRI equipment, availability for ED imaging, and number of slices for the available CT scanners. The analysis was stratified by site characteristics.

RESULTS

The authors collected data from 260 institutions (99% response). In this random sample of EDs, the median annual patient visit volume was 19,872 (interquartile range = 6,788 to 35,757), 28% (95% confidence interval [CI] = 22% to 33%) were rural, and 27% (95% CI = 21% to 32%) participated in the Critical Access Hospital program. CT scanners were present in 249 (96%) institutions, and of these, 235 (94%) had 24/7 access for ED patients. CT scanner resolution varied: 28% had 1-4 slice, 33% had 5-16 slice, and 39% had a more than 16 slice. On-site MRI was available for 171 (66%) institutions, and mobile MRI for 53 (20%). Smaller, rural, and critical access hospitals had lower CT and MRI availability and less access to higher-resolution CT scanners.

CONCLUSIONS

Although access to CT imaging was high (>90%), CT resolution and access to MRI were variable. Based on observed differences, the availability and quality of imaging equipment may vary by ED size and location.

Gallbladder torsion: preoperative diagnosis by MDCT

The patient was a 80-year-old female who was diagnosed as having gallbladder torsion preoperatively. To out knowledge, this is the first reported case diagnosed by CT with a multidetector CT scanner. The abdominal CT showed a V-shape distortion of the extrahepatic ducts, twisting cystic artery with "Whirl's sign", distended and enlarged gallbladder with wall hemorrhage. A definitive diagnosis of gallbladder torsion was made by CT preoperatively. If treated surgically, gallbladder detorsion before cholecystectomy is a helpful technique to avoid bile duct injury. This condition should be suspected in elderly women with acute abdominal pain of unknown origin, and MDCT with multiplanar reformation is very useful in making a definitive diagnosis.

MDCT diagnosis of ruptured tubal pregnancy with massive hemoperitoneum

We report a case of ruptured tubal pregnancy with massive life-threatening hemoperitoneum. The 38 year-old woman presented with gynaecologic haemorrhage, pelvic pain and hypovolemic shock. Without any ambiguity, the diagnosis was directly made during contrast enhanced Multidetector Computed Tomography (MDCT). Massive hemoperitoneum with fresh blood clots in the hypogastric area, active free peritoneal extravasation of intravascular contrast material and dramatic peripheral enhancement, - "ring of fire" sign - of an adnexal cystic structure were the key signs. These signs must be known by the emergency radiologist because of the more and more use of CT as the first imaging modality in emergency departments particularly for patients with abdominal pain and presenting life-threatening symptoms.

Fitz-Hugh-Curtis syndrome: CT findings of three cases

Clinical manifestations and computed tomography (CT) findings of Fitz-Hugh-Curtis syndrome (FHCS) are relatively well stabilized as right upper quadrant abdominal pain and hepatic capsular enhancement because of perihepatitis associated with pelvic inflammatory disease caused by N. gonorrhoeae and C. trachomatis. We encountered three patients with serial FHCS associated with pelvic inflammatory disease, who visited the emergency room with right upper quadrant abdominal pain. Abdominal CT revealed hepatic capsular or pericapsular enhancement along the anterior surface of the liver on the arterial phase. Recently, multi-detector CT has evolved as the first-line imaging modality of acute abdomen at the emergency room; we reemphasized the importance of the CT findings of this syndrome for differential diagnosis of right upper quadrant abdominal pain in sexually active young women. Physicians at the emergency room acknowledge the syndrome and should perform dynamic abdominopelvic CT including the arterial phase.

Direct visualization of perforation sites in patients with a non-traumatic free pneumoperitoneum: added diagnostic value of thin transverse slices and coronal and sagittal reformations for multi-detector CT

The incremental diagnostic value of adding 1.25-mm slices and coronal and sagittal reformatting to 5-mm axial reconstructions for direct visualization of the perforation site in patients with non-traumatic free pneumoperitoneum was assessed. Forty patients with non-traumatic bowel perforation and free pneumoperitoneum underwent computed tomography (CT). The perforation was gastroduodenal in 18 patients and involved the small or large bowel in 22 patients. Transverse scans were reconstructed with 5-mm thick sections at 5-mm intervals and 1.25-mm-thick sections at 1.25-mm intervals. The second data set was reformatted coronally and sagittaly with 3-mm-thick sections at 3-mm intervals. Three independent blinded readers interpreted 5-mm transverse scans, then combined 1.25-mm and 5-mm-transverse scans, and then combined transverse, coronal and sagittal scans. The rate of identification of the perforation site ranged from 43% to 53% with the combined axial, sagittal and coronal scans, from 28% to 48% with the 1.25- and 5-mm transverse scans, and from 5% to 20% only with the 5-mm thick transverse scans. The agreement between readers was significantly higher with thin slices and reformatting. The use of 1.25-mm axial slices and reformations intrinsically contained more useful diagnostic information than 5-mm axial slices alone for diagnosis of the perforation site in patients with pneumoperitoneum.

Acute abdomen: Added diagnostic value of coronal reformations with 64-slice multidetector row computed tomography

RATIONALE AND OBJECTIVES

We sought to assess retrospectively the added value of coronal reformations from isotropic voxels obtained with 64-slice multidetector row computed tomography (CT) of the acute abdomen.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board and informed consent was waived. Multidetector helical 64-section CT (section thickness, 0.6 mm; pitch 1.75; table speed 35 mm/sec) was performed in 100 patients (60 women and 40 men; age range, 9-/+85 years; mean age, 45.2 years) with acute nontraumatic abdominal pain who had been referred from the emergency department. Axial images were reconstructed with 5-mm-thick sections at 5-mm intervals. The second data set was reformatted coronally, with 3-mm-thick sections at 3-mm intervals. Four independent, blinded readers with various level of training interpreted first the axial scans alone and then followed immediately by the coronal scans. Confidence in the visualization of anatomy and pathology was scored on a 5-point scale. The final diagnosis was determined by surgical and pathologic reports and by clinical follow-up in those who did not undergo surgery.

RESULTS

Based upon the individual patient's clinical history and other comorbid factors, 92 patients received intravenous contrast and 90 patients received oral contrast. In 45 patients, no CT abnormalities were detected for an explanation of the abdominal pain. Mean sensitivity and specificity of axial CT alone were 92.5% and 91%, respectively. No significant differences in sensitivity and specificity were observed for the use of combined axial and coronal images. For the most inexperienced reader, the coronal reformations were helpful in 95% of cases, while for the most experienced reader, the coronal reformations were helpful in 35% of the cases. The coronal images were deemed helpful in an average of 62.3% of the cases for the four readers. However, diagnosing subtle pathology in the abdominal wall was difficult on coronal reformations alone. Overall, coronal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal abdominal structures and in the diagnosis of abdominal pathology.

CONCLUSION

Axial and coronal reformations of 64-section multidetector row CT have equal sensitivity and specificity for the diagnosis of acute abdominal pathology. However, coronal reformations improved the diagnostic confidence for all readers but most significantly for the least experienced. Therefore, radiology departments with residents should consider routinely generating coronal images in patients with acute abdominal pain.

Acute gastrointestinal bleeding: detection of source and etiology with multi-detector-row CT

This study was conducted to determine the ability of multi-detector-row computed tomography (CT) to identify the source and etiology of acute gastrointestinal bleeding. Eighteen patients with acute upper (n = 10) and lower (n = 8) gastrointestinal bleeding underwent 4-detector-row CT (n = 6), 16-detector-row CT (n = 11), and 64-slice CT (n = 1) with an arterial and portal venous phase of contrast enhancement. Unenhanced scans were performed in nine patients. CT scans were reviewed to determine conspicuity of bleeding source, underlying etiology, and for potential causes of false-negative prospective interpretations. Bleeding sources were prospectively identified with CT in 15 (83%) patients, and three (17%) bleeding sources were visualized in retrospect, allowing the characterization of all sources of bleeding with CT. Contrast extravasation was demonstrated with CT in all 11 patients with severe bleeding, but only in 1 of 7 patients with mild bleeding. The etiology could not be identified on unenhanced CT scans in any patient, whereas arterial-phase and portal venous-phase CT depicted etiology in 15 (83%) patients. Underlying etiology was correctly identified in all eight patients with mild GI bleeding. Multi-detector-row CT enables the identification of bleeding source and precise etiology in patients with acute gastrointestinal bleeding.

Multidetector row computed tomography findings from ischemia to infarction of the large bowel

OBJECTIVE

MDCT is performed as first imaging examination for patients with acute abdomen in most Emergency Departments. Clinical suspicion of ischemic colitis and infarction is related to specific findings, however, differential diagnosis as well as the staging for a confirmed ischemic affection may be critical. The individual signs from ischemia to infarction of large bowel is a captivating topic. In this study, we report our experience of the MDCT assessment of acute colonic disease from vascular mesenteric disorders.

MATERIALS AND METHODS

We retrospectively reviewed the MDCT findings of 71 patients admitted to our attention for acute abdomen, with final proven diagnosis of colonic ischemia and/or infarction made by surgery and/or endoscopy. CT-scanning of the abdomen and pelvis was performed after i.v. contrast medium administration, using a multidetector row CT equipment. We correlated the presence of parietal disease, the evidence of mesenteric arterial or venous vessels occlusion, the parietal features as well as others findings, such as free fluid and/or air in peritoneal recess or in retroperitoneum, with the surgical and/or endoscopic findings.

RESULTS

Analysis of our data showed a segmental (84%) or complete (16%) involvement of the colon; 57 cases were related to ischemia, 14 to infarction. Inferior mesenteric vessels defect of opacification was noted in 10 cases. Various degree of wall thickening and parietal enhancement, peritoneal fluid, mural or portal-mesenteric pneumatosis were compared to evidence of mesenteric arterial or vein occlusion and to final proven diagnosis. A classification in a multi-stage grading for both decreased of arterial supply or impaired venous drainage disorders was done.

CONCLUSIONS

A grading scale from ischemia to infarction affecting the large bowel from arterial or venous mesenteric vessels origin has been not previously reported in a series at our knowledge. MDCT findings may support the clinical evaluation of patients affected by acute colon from vascular disorders. In particular, it seems to provide effective and valuable information's in differentiating etiology and stage of disease.

Impact of the introduction of 16-row MDCT on image quality and patient dose: phantom study and multi-centre survey

The purpose was to compare the image quality and patient dose between 4- and 16-row MDCT units and to evaluate the dispersion of the dose delivered for common clinical examinations. Four 4- and 16-row MDCT units were used in the study. Image noise levels from images of a CatPhan phantom were compared for all units using a given CTDI(vol) of 15.0+/-1.0 mGy. Standard acquisition protocols from ten centres, shifted from 4- to 16-row MDCT (plus one additional centre for 16-row MDCT), were compared for cerebral angiography and standard chest and abdomen examinations. In addition, the protocols used with 16-row MDCT units for diagnosis of the unstable shoulder and for cardiac examinations were also compared. The introduction of 16-MSCT units did not reduce the performance of the detectors. Concerning the acquisition protocols, a wide range in practice was observed for standard examinations; DLP varied from 800 to 5,120 mGy x cm, 130 to 860 mGy x cm, 410 to 1,790 mGy x cm and 850 to 2,500 mGy x cm for cerebral angiography, standard chest, standard abdomen and heart examinations, respectively. The introduction of 16-row MDCT did not, on average, increase the patient dose for standard chest and abdominal examinations. However, a significant dose increase has been observed for cerebral angiography. There is a wide dispersion in the doses delivered, especially for cardiac imaging.