Efficiency of unenhanced MRI in the diagnosis of acute appendicitis: Comparison with Alvarado scoring system and histopathological results

Purpose

The purpose of this study was to assess the diagnostic value of unenhanced magnetic resonance imaging (MRI) in the diagnosis of acute appendicitis and compare with Alvarado scores and histopathological results.

Materials and methods

The study included 85 consecutive patients (mean age, 26.5 ± 11.3 years) who were clinically suspected of having acute appendicitis. Each patients Alvarado scores were recorded and unenhanced MRI was performed, consisting of T1-weighted, T2-weighted and fat-suppressed T2-weighted fast spin-echo sequences. The MR images were prospectively reviewed in consensus for the presence of acute appendicitis by two radiologists who were blinded to the results of the Alvarado scores.The study population were divided into three subgroups based on the MRI findings: Group I: definitely not appendicitis, Group II: probably appendicitis, Group III: definitely appendicitis. All patients were divided into two subgroups according to Alvarado scores as Group A (low: 1-6), and Group B (high: 7-10). MR findings were compared with Alvarado scores and histopathological findings.

Results

Sixty-six (77.6%) of the 85 patients with clinically suspected acute appendicitis, had undergone surgery. The diagnosis of appendicitis could be correctly achieved with MRI in 55 (83.3%) of 57 (86.4%) patients with histopathologically proven acute appendicitis. The sensitivity, specificity, positive predictive value and negative predictive value of MRI examination and Alvarado scoring system in the diagnosis of acute appendicitis were 96.49%, 66.67%, 94.83%, 75.0% and 84.21%, 66.67%, 94.12%, 40.0%, respectively.

Conclusions

MRI is a valuable technique for detecting acute appendicitis even in the cases with low Alvarado scores. To increase the diagnostic accuracy and preventing unnecessary laparotomies for suspected appendicitis, shorter and cheaper unenhanced basic MRI may be performed.     

Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

Objectives

Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.

Materials and methods

Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference.

Results

Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries.

Conclusions

Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.     

CT features of adenomyosis

Objectives

To determine the computed tomography (CT) features of adenomyosis in patients with known adenomyosis as established with magnetic resonance (MR) imaging.

Methods

A computerized search identified 16 women with pelvic MR diagnosis of adenomyosis who also had enhanced pelvic CT. Original CT reports were reviewed for potential prospective diagnosis of adenomyosis. CT images were reviewed for enhancement phase, inner and outer myometrium attenuation, uterine enlargement (width>6 cm), inner myometrial thickening (≥12 mm), and myometrial cysts.

Results

Adenomyosis was detectable on CT in 8 of 16 patients. For these 8 patients, inner and outer myometrium distinction was excellent in 7 (88%) and limited in 1 (12%), and mean inner myometrial thickness was 25 mm (range 14-47 mm). CT enhancement phase was parenchymal in 7 (88%), uterus was enlarged in 8 (100%), and 7 (88%) had myometrial cysts. Adenomyosis was focal in 5 (63%), diffuse in 2 (25%), and both in 1 (12%). None of the original CT reports included adenomyosis as a diagnosis.

Conclusions

CT can suggest a diagnosis of adenomyosis based on uterine enlargement, thickened inner myometrium, and/or myometrial cysts.     

Retroperitoneal ganglioneuroma in children: CT and MRI features with histologic correlation

Objective

To demonstrate the CT and MRI features with histologic correlation of retroperitoneal ganglioneuromas in children.

Methods

The diagnostic images (seventeen CT scans and five MR scans) in 17 children with retroperitoneal ganglioneuroma confirmed by operation and histopathology were retrospectively reviewed, and correlated to the histologic findings.

Results

All tumors presented as an oval-shaped, well-defined mass on both CT and MR images. On unenhanced CT images, calcification was detected in six masses (35.3%), and predominantly low attenuation with the CT value ranged from 22 to 38 HU (mean 29.5 HU) in all the tumors. The tumors with CT value less than 30 HU had a relatively larger amount of myxoid stroma on histopathologic sections than those with CT value more than 30 HU. Tumors showed homogeneous low signal intensity on T1-weighted images and inhomogeneous high signal intensity with interlaced or nodular low signal intensity on T2-weighted images. The post-contrast enhancement on both CT and MR images was lacking or slight in early phase, but moderate or marked in late phase. The inhomogeneous high signal intensity on T2WI, as well as the delayed enhancement corresponded to a large amount of myxoid stroma and a relatively small number of cellular components in tumors.

Conclusion

An oval shape, well-defined margin, low attenuation on CT, inhomogeneous hyperintensity on T2WI, and delayed moderate or marked enhancement are typical features of retroperitoneal ganglioneuroma in children. The imaging features correlated well to the histologic findings.     

CT and MR findings in synovial chondromatosis of the temporo-mandibular joint: Our experience and review of literature

Objective

To compare Computed Tomography (CT) and Magnetic Resonance (MR) features and their diagnostic potential in the assessment of Synovial Chondromatosis (SC) of the Temporo-Mandibular Joint (TMJ).

Materials and methods

Eight patients with symptoms and signs compatible with dysfunctional disorders of the TMJ underwent CT and MR scan. We considered the following parameters: soft tissue involvement (disk included), osteostructural alterations of the joints, loose bodies and intra-articular fluid. These parameters were evaluated separately by two radiologists with a “double blinded method” and then, after agreement, definitive assessment of the parameters was given. CT and MR findings were compared.

Results

Histopathological results showed metaplastic synovia in all patients and therefore confirmed diagnosis of SC. MR resulted better than CT in the evaluation of all parameters except the osteostructural alterations of the joints, estimated with more accuracy by CT scan.

Conclusions

CT scan is excellent to define bony surfaces of the articular joints and flogistic tissue but it fails in the detection of loose bodies when these are not yet calcified. MR scan therefore is the gold standard when SC is suspected since it can visualize loose bodies at early stage and also evaluate disk condition and eventual extra-articular tissues involvement. The use of T2-weighted images and contrast medium allows identifying intra-articular fluid, estimating its entity and discriminating from sinovial tissue.     

Multidetector helical CT in the evaluation of acute small bowel obstruction: comparison of non-enhanced (no oral, rectal or IV contrast) and IV enhanced CT

Purpose

To compare accuracy of non-enhanced CT (NECT) (no oral or IV contrast) and enhanced CT (ECT) (IV enhanced only) to diagnose small bowel obstruction and evaluate reviewer's experience impact.

Materials and methods

Ninety-nine adult patients underwent 105 NECT and ECT (6 patients had 2 examinations) on a four-detector CT. An abdominal radiologist, an abdominal imaging fellow, a second-year radiology resident retrospectively reviewed NECTs and ECTs separately and independently blinded to outcome. Discrepancy of diameter of proximal and distal small bowel ± a transition was considered indication of mechanical bowel obstruction. Reference standard was surgery in 26 and chart review in 79.

Results

Mechanical obstruction was present in 56% (59/105). The average sensitivity, specificity, negative and positive predictive and accuracy values for NECT were 88.1% (CI: 80-96%), 77% (CI: 65-89%), 83.0% (CI: 72-95%), 83% (CI: 74-92%), and 83% (CI: 76-90%) with no significant difference between three reviewers. The corresponding numbers for ECT were 87.6% (CI: 79-96%), 75% (CI: 63-88%), 82.6.0% (CI: 71-94%), 82.1% (CI: 73-92%), and 82% (CI: 75-90%) (p > 0.5). Area under curve (AUC) of ROC curves of three reviewers did not show significant statistical difference (p > 0.5).

Conclusions

NECT and ECT have comparable accuracy to diagnose mechanical small bowel obstruction and can be interpreted by reviewers with different levels of expertise.     

Prospective versus retrospective ECG gating for 320-detector CT of the coronary arteries: comparison of image quality and patient radiation dose

Purpose

To compare image quality and patient radiation dose in a group of patients who underwent 320-detector computed tomography coronary angiography performed with prospective electrocardiogram (ECG) gating with image quality and radiation dose in a group of patients matched for clinical features who underwent 320-detector computed tomographic (CT) coronary angiography performed with retrospective ECG gating.

Materials and Methods

This study was approved by our institutional human research committee. All patients had clinical indications for coronary computed tomography angiography (CTA). Two independent reviewers separately scored coronary artery segment image quality for 480 cardiac CT studies in prospective group and retrospective group (240 in each group). Reviewer variability was calculated. Estimated effective radiation dose was compared for prospective versus retrospective ECG gating.

Results

The two groups matched well for clinical characteristics and CT parameters. There was good agreement for coronary artery segment image quality scores between the independent reviewers (k=0.73). Of the 6408 coronary artery segments scored, there were no coronary artery segments that could not be evaluated in each group. Image quality scores were not significantly different (P>.05). Mean patient radiation dose was 76.50% lower for prospective gating (4.2 mSv) than for retrospective gating (18.1 mSv) (P<.01).

Conclusion

Use of 320-detector CT coronary angiography performed with prospective ECG gating has similar subjective image quality scores but 76.50% lower patient radiation dose when compared with use of retrospective ECG gating.     

Xanthogranulomatous cholecystitis: Diagnostic performance of CT to differentiate from gallbladder cancer

Purpose

To retrospectively evaluate CT findings of xanthogranulomatous cholecystitis (XGC) and to measure diagnostic performance for distinguishing it from gallbladder (GB) cancer.

Methods and materials

Our institutional review board approved this retrospective study. Three blinded radiologists, first independently and then in consensus, retrospectively evaluated postcontrast CT images of 35 patients with histopathologically proved XGC and GB cancer, all of whom subsequently had cholecystectomy. These included 18 patients with XGC (13 male, 5 female; age range, 35-84, mean 63 years) and 17 with GB cancer (6 male, 11 female; age range, 45-95, mean 69). Differences in CT findings between XGC and GB cancer and diagnostic performances for each CT finding were calculated. Sensitivity, specificity, and accuracy were calculated for each radiologist and observer performance was also determined by receiver-operating-characteristic curve analysis.

Results

Five CT findings showed significant differences between XGC and GB cancer. Sensitivity, specificity, and accuracy of each finding for the differentiation of XGC were 89%, 65%, 77% with diffuse GB wall thickening, 67%, 82%, 74% with a continuous mucosal line, 61%, 71%, 66% with intra-mural hypo-attenuated nodules, 72%, 77%, 74% with absence of macroscopic hepatic invasion, and 67%, 71%, 69% with absence of intra-hepatic bile duct dilatation, respectively. When at least three of these five CT findings were observed in combination, sensitivity, specificity, and accuracy were 83%, 100% and 91%, respectively. Sensitivities, specificities and Az values for the differentiation of XGC from GB cancer were 83%, 88%, 0.94 for reader 1, 78%, 88%, 0.93 for reader 2, and 78%, 82%, 0.84 for reader 3.

Conclusions

The combination of three of the five CT findings that are common with XGC can provide excellent accuracy for the differentiation of XGC and GB cancer.     

Improvement of pulmonary angiography in the framework of a maintenance of certification

Purpose

This evaluation of clinical practices (pulmonary embolus) was performed to evaluate the quality of CT pulmonary angiograms for suspected acute pulmonary embolus.

Materials and methods

Five validated criteria evaluating both the acquisition technique and the quality of image interpretation were selected: slice thickness, pulmonary arterial enhancement over 250 HU, caudocranial acquisition, visualization of fifth order pulmonary arterial branches, and right-left ventricular ratio in the presence of pulmonary embolus. Forty CT pulmonary angiograms were reviewed before and after implementation of a practice quality improvement program: modification of acquisition protocol, training of medical and paramedical staff, and implementation of a standardized radiology report.

Results

Thin collimation was already implemented. The implementation of two other technical parameters significantly improved the technical quality of the examinations. The detection of findings with adverse clinical outcome was also significantly improved. Only the accuracy of detection of embolus involving fifth order pulmonary arterial branches could not be improved, a criteria allowing formal exclusion of pulmonary embolus.

Conclusion

This study resulted in an improvement in the quality of CT pulmonary angiograms and increased awareness of radiologists for the prognostic value of right ventricular dilatation. It has also underscored the need for quality control of a CT pulmonary angiogram prior to interpretation.     

Improving low-dose abdominal CT images by Weighted Intensity Averaging over Large-scale Neighborhoods

Purpose

Though highly desirable in radiologic procedures, low-dose CT (LDCT) images tend to be severely degraded by quantum noise and non-stationary artifacts. The purpose of this paper is to improve the abdominal LDCT images by the approach of Weighted Intensity Averaging over Large-scale Neighborhoods (WIA-LN).

Materials and methods

In the implementation of the proposed WIA-LN method, the processed pixel intensities are adaptively calculated as the weighted intensity averaging of the pixels with similar surrounding structures throughout a large-scale neighborhood. Both phantom and clinical abdominal CT images from a 16 detector rows Siemens CT were acquired at standard and 80% reduced tube current time products (150 mA s and 30 mA s corresponding to standard-dose and low-dose protocols, respectively). Visual comparison, statistical qualitative analysis (image quality scores and hepatic cyst diagnosis), and quantitative calculation (noise and contrast-to-noise ratio) are made.

Results

Better vision and quantitative performance are realized using the proposed WIA-LN method. Compared to original LDCT and standard-dose CT (SDCT) images, statistically significant improvement of noise/artifacts suppression, contrast preservation and hepatic cyst detection in LDCT images are achieved by using the proposed method (P < 0.05).

Conclusion

With the tube current reduced to approximate one-fifth of the standard tube current setting, clinically acceptable images can still be obtained by using the proposed method.     

Value of CT lymphangiography in the detection of lymphatic leakage: a report of nine cases

Purpose

To demonstrate the value of CT lymphangiography to detect lymphatic leakage, especially at the thoracic level, prior to therapeutic intervention.

Patients and methods

Between 2004 and 2008, nine patients underwent lymphangiography, followed by CT for the evaluation of intractable lymphatic leakage in spite of optimal medical management. Patients included seven females and two males, with age ranging between 25 and 58 years. Lymphangiography was performed after unilateral or bilateral foot injection(s) of Lipiodol ultrafluid followed by standard radiographs of the chest and abdomen and CT of the chest, abdomen and pelvis. The images were reviewed by two experienced radiologists.

Results

Lipiodol leakage was observed in six patients, while three patients showed evidence of lymphangiectasia of the abdominal and/or thoracic lymphatics. Spontaneous resolution of leakage after lymphangiography occurred in three cases.

Conclusion

CT lymphangiography allows direct evaluation of lymphatics, from pelvis to chest, in order to detect the site of leakage at the origin of a chylous effusion and assist in its management.     

Osteoid osteoma in atypical locations: the added value of dynamic gadolinium-enhanced MR imaging

Purpose

To compare the results of dynamic gadolinium-enhanced magnetic resonance imaging (MRI), unenhanced MRI and computed tomography (CT), in terms of nidus conspicuity and diagnostic confidence of osteoid osteoma in atypical sites.

Materials and methods

CT and MR (nonenhanced T1- and T2-weighted and dynamic MRI) images of 19 patients with histologically proven osteoid osteoma located in atypical sites were retrospectively reviewed. Time-enhancement curves of the nidus and the adjacent bone marrow were generated. Images from each technique were scored for nidus conspicuity by two independent radiologists. Another blinded radiologist was asked to assess final diagnosis of the bone lesion on MR and CT images, independently.

Results

In all cases, nidus contrast uptake started in the arterial phase and was higher compared to the surrounding bone marrow. Dynamic MRI significantly increased nidus conspicuity compared to nonenhanced MRI (P < .0001) and CT (P = .04). In 6/19 (31.6%) cases nidus conspicuity was higher at dynamic MRI compared to CT. Confident diagnosis of osteoid osteoma was achieved in all patients with MRI and in 10/19 (52.6%) patients with CT.

Conclusion

In patients with osteoid osteoma located in atypical sites, dynamic MRI increases nidus conspicuity, allowing confident diagnosis.     

Thin-section CT of the mediastinum in preoperative N-staging of non-small cell lung cancer: Comparison with FDG PET

Purpose

To compare diagnostic capability of preoperative N-staging of lung cancer between thin-section CT of the mediastinum and FDG PET, and 5 mm slice thickness CT.

Materials and methods

The subjects were 34 patients with lung carcinoma who were examined by both CT and PET, and subsequently underwent surgery between May 2005 and January 2007. CT was carried out with a 16 detector row helical CT scanner. The raw data were reconstructed into 5 mm slice thickness and 1 mm slice thickness (thin-section CT). A total of 251 lymph node stations were retrospectively assessed for the presence of lymph node metastasis with thin-section CT, 5 mm CT and PET. In the interpretations of thin-section CT and 5 mm CT, we employed multi-criteria as follows: nodular calcification and intranodal fat as benign criteria, and short-axis diameter more than 10 mm (size criterion), focal low density other than fat, surrounding fat infiltration and convex margin in hilar lymph nodes, as malignant criteria. On PET, maximum standardized uptake value (SUVmax) of 2.5 or more was used as the criterion of malignancy. Sensitivity and specificity were compared between these examinations using McNemar test.

Results

Sensitivities and specificities of thin-section CT, 5 mm CT and PET were 25%, 25%, 25%, and 97%, 94%, 98%, respectively. The statistical analysis revealed that the specificity of 5 mm CT was significantly lower than those of thin-section CT (p = 0.039) and PET (p = 0.006), while no difference was present between thin-section CT and PET.

Conclusion

Thin-section CT of the mediastinum using multiple criteria was comparable to PET in preoperative N-staging of lung cancer.     

Non-enhanced MR angiography of renal artery using inflow-sensitive inversion recovery pulse sequence: A prospective comparison with enhanced CT angiography

Purpose

To prospectively evaluate the diagnostic value of non-enhanced inflow-sensitive inversion recovery (IFIR) MR angiography for the detection of renal artery stenosis (RAS), with enhanced CT angiography performed as the reference standard.

Materials and methods

Sixty consecutive patients suspected of RAS underwent both of IFIR MR and enhanced CT angiography. Subjective image quality, renal artery depiction and renal artery grading were all evaluated on artery-by-artery basis. Spearman rank correlation analysis was used to assess agreement between the two techniques. The diagnostic sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for RAS detection at IFIR MR angiography were calculated.

Results

One hundred twenty-six main renal arteries were visualized on enhanced CT and non-enhanced MR angiographic images, respectively. The Spearman rank correlation was 0.773 (P < .001) for renal artery depiction, 0.998 (P < .001) for renal arteries grading and 0.833 (P < .001) for RAS detection between the two modalities. The sensitivity, specificity, PPV and NPV of IFIR MR angiography for RAS detection demonstrated 100%, 99.0%, 92.0% and 100%, respectively.

Conclusion

Non-enhanced IFIR MR angiography had high sensitivity, specificity, PPV and NPV for RAS detection. It could be the first choice of renal artery imaging methods to avoid ionizing irradiation and renal toxicity from contrast media.     

Artifacts in spiral CT protocols: The importance of the spatial reconstruction

Purpose

This study recorded and analysed streak and motion artifacts in spiral CT examinations and evaluated the elimination and minimization of them by the use of segmental reconstruction with and without alterations of the initial examination protocol.

Materials and methods

One hundred CT scans of the chest and 300 CT scans of the brain have been included in this study. All studies were performed by a helical CT scanner (Philips 5000 SR) with the standard protocol and were randomly selected due to the presence of either streak or motion artifacts. Segmental reconstruction was applied in all cases by the same experienced radiographer. Image evaluation was performed by two experienced radiologists using a scoring system for each artifact and a grading system for classifying post-processing images.

Results

Among series of images that were evaluated after the application of segmental reconstruction, brain examinations demonstrated the following results: 10.9% of the cases showed no artifact improvement, 19.6% showed slight artifact improvement 31.5% showed moderate improvement and 38% showed significant improvement. The results of chest examinations were as follows: 27% of the cases showed no artifact improvement, 23% showed slight artifact improvement, 26% showed moderate improvement and 24% of showed significant improvement. Spatial reconstruction was useless in brain CT images when a patient moved during the entire scan and in chest CT images when streak and motion artifacts co-existed.

Conclusions

Spatial reconstruction may improve the image quality in brain and chest CT examinations and thus may contribute to more diagnostic images. Elimination of motion artifacts is also suggested due to the limitation of intravenous contrast medium that can be administered per patient per day and in cases of non-cooperative patients.     

Early and late-onset acute GvHD following hematopoietic cell transplantation: CT features of gastrointestinal involvement with clinical and pathological correlation

Objective

With the introduction of non-myeloablative hematopoietic cell transplantation, acute graft-versus-host-disease (GvHD) is frequently observed beyond the traditional 100 days cut-off.The aim of this study was to describe and compare CT features of gastrointestinal early and late-onset GvHD and to correlate findings with clinical and pathology grading.

Subjects and methods

Abdominal CT scans were obtained in 20 patients with early and 15 with late-onset GvHD. Examinations were assessed for intestinal and extraintestinal abnormalities and findings compared between the two subgroups of GvHD. Distinct CT abnormalities as well as a CT-score integrating multiple pathologies were correlated with gut, clinical or pathology grading.

Results

Frequent intestinal abnormalities included wall thickening, abnormal enhancement, and excessive fluid-filling (94%, 89%, and 94%). 86% of patients showed concomitant small and large bowel involvement. A discontinuous distribution was observed in 54%. Bile tract abnormality was the most common extra-intestinal finding (74%).The distribution of pathologies was equal between subgroups of early or late-onset disease.Wall thickening and mucosal attenuation in non-enhanced scans were significantly related to clinical and pathology scores (P ≤ 0.018). Number of abnormal segments, small bowel dilatation, engorgement of the vasa recta, mesenteric fat stranding and ascites were linked to clinical grading (P ≤ 0.019). A CT-score integrating multiple abnormalities was correlated to gut, overall clinical and pathology grading (r = 0.64, 0.57, 0.50).

Conclusion

CT morphology of acute GvHD is independent of its time of onset and, thus, facilitates differential diagnosis of late-onset acute GvHD. Correlation of CT morphology with clinical and pathological grading is important in terms of prognosis and may help guiding the therapeutic approach.     

Fever of unknown origin: A value of F-FDG-PET/CT with integrated full diagnostic isotropic CT imaging

Aim

The aim of presented work is to evaluate the clinical value of ¹⁸F-FDG-PET/CT in patients with fever of unknown origin (FUO) and to compare PET/CT finding with the results of the following investigation.

Material and method

48 patients (24 men, 24 women, mean age 57.6 years with range 15-89 years) underwent ¹⁸F-FDG-PET/CT due to the fever of unknown origin. All examinations were performed using complex PET/CT protocol combined PET and whole diagnostic contrast enhanced CT with sub-millimeter spatial resolution (except patient with history of iodine hypersensitivity or sever renal impairment). CT data contained diagnostic images reconstructed with soft tissue and high-resolution algorithm. PET/CT finding were compared with results of biopsies, immunology, microbiology or autopsy.

Results

The cause of FUO was explained according to the PET/CT findings and followed investigations in 44 of 48 cases—18 cases of microbial infections, nine cases of autoimmune inflammations, four cases of non-infectious granulomatous diseases, eight cases of malignancies and five cases of proved immunity disorders were found. In 46 cases, the PET/CT interpretation was correct. Only in one case, the cause was overlooked and the uptake in atherosclerotic changes of arteries was misinterpreted as vasculitis in the other. The reached sensitivity was 97% (43/44), and specificity 75% (3/4) respectively.

Conclusion

In patients with fever of unknown origin, ¹⁸F-FDG-PET/CT might enable the detection of its cause.     

Unenhanced MR Imaging in adults with clinically suspected acute appendicitis

Purpose

The purpose of the study was to evaluate unenhanced Magnetic Resonance Imaging (MRI) for the diagnosis of appendicitis or another surgery-requiring condition in an adult population scheduled for emergency appendectomy based on a clinical diagnosis of suspected acute appendicitis.

Materials and methods

The prospective study included 48 consecutive patients (29 female, 19 male, 18-70 years old, mean age = 37.1 years). MRI examination was designed to be comfortable and fast; no contrast was administered. The sequences were performed during quiet respiration. The MRI findings were reviewed by two radiologists and one surgeon independent of each other and compared with surgical and pathological records.

Results

According to the surgical and histopathological findings 30 of 48 patients (63%) had acute appendicitis. Of the remaining 18 patients, 4 patients had no reasons for the clinical symptoms and 14 patients had other pathology.For the three reviewers the performance of MRI in the diagnosis of acute appendicitis showed the following sensitivity, specificity and accuracy ranges: 83-93%, 50-83% and 77-83%. Moderate (κ = 0.51) and fair (κ = 0.31) interobserver agreements in the MR diagnosis of acute appendicitis were found between the reviewers. Sensitivity, specificity and accuracy values for overall performance of MRI in detecting pelvic abnormalities were 100%, 75% (3 of 4 healthy patients were identified by MRI) and 98%, respectively.

Conclusion

Unenhanced fast MRI is feasible as an additional fast screening before the appendectomy. It may prevent unnecessary surgeries. The fast MRI examination can be adequately performed on an MRI unit of broad range of field strengths.     

Dual energy CT at the synchrotron: A piglet model for neurovascular research

Background

Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT.

Materials and methods

All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360°. CT images were reconstructed from two half-acquisitions with 720 projections each.

Results

The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models.     

Quantitative assessment of perirectal tumor infiltration with dynamic contrast-enhanced multi-detector row CT in rectal cancer

Objective

To evaluate the efficacy of discriminant function analysis of perirectal tumor infiltration with dynamic contrast-enhanced 64-detector row CT in rectal cancer.

Materials and methods

Forty-nine patients with rectal cancer underwent dynamic contrast-enhanced CT. A total of 96 axial CT slices containing the tumors were evaluated. The 96 images were separated into two groups with or without perirectal tumor infiltration based on pathological findings. The discriminant function was set-up using CT density differences between the mass and the adjacent perirectal tissue within 5 mm from the mass at 20 and 40 s as independent variables. The results of the discriminant function analysis were compared to those of CT morphology and pathology.

Results

CT morphological diagnosis was accurate on 71.9% (69/96) of the slices with 82.5% sensitivity and 64.3% specificity. Discriminant function analysis correctly identified 88.5% (85/96) of the slices with 85.0% sensitivity and 91.1% specificity. Overstaging occurred significantly more (P < 0.05) on morphological analysis (20.8%, 20/96) than discriminant function analysis (5.2%, 5/96) of the CT slices.

Conclusions

Discriminant function analysis of dynamic contrast-enhanced CT improves the diagnostic accuracy and specificity of perirectal tumor infiltration in rectal cancer.