Computer-aided detection of pulmonary embolism: Influence on radiologists’ detection performance with respect to vessel segments

The purpose was to assess the sensitivity of a CAD software prototype for the detection of pulmonary embolism in MDCT chest examinations with regard to vessel level and to assess the influence on radiologists' detection performance. Forty-three patients with suspected PE were included in this retrospective study. MDCT chest examinations with a standard PE protocol were acquired at a 16-slice MDCT. All patient data were read by three radiologists (R1, R2, R3), and all thrombi were marked. A CAD prototype software was applied to all datasets, and each finding of the software was analyzed with regard to vessel level. The standard of reference was assessed in a consensus read. Sensitivity for the radiologists and CAD software was assessed. Thirty-three patients were positive for PE, with a total of 215 thrombi. The mean overall sensitivity for the CAD software alone was 83% (specificity, 80%). Radiologist sensitivity was 77% = R3, 82% = R2, and R1 = 87%. With the aid of the CAD software, sensitivities increased to 98% (R1), 93% (R2), and 92% (R3) (p<0.0001). CAD performance at the lobar level was 87%, at the segmental 90% and at the subsegmental 77%. With the use of CAD for PE, the detection performance of radiologists can be improved.     

Imaging findings of complications affecting the upper extremity in intravenous drug users: featured cases

Infections generally occur in intravenous drug abuse (IVDA) patients, most commonly affecting the spine and proximal joints. Numerous serious musculoskeletal complications of IVDA may involve the upper extremity, however. Soft-tissue complications in the upper extremity of IVDA patients include cellulitis, ulceration, abscess, pyomyositis, septic bursitis, tenosynovitis, and necrotizing fasciitis. Foreign bodies in soft tissue due to needle fragments are common findings. Primary bone and joint IVDA complications include osteomyelitis (acute and chronic) and septic arthritis. Other IVDA complications in the upper extremity affecting blood vessels and lymphatics include hematoma, arterial aneurysm and pseudoaneurysm, thrombosis, thrombophlebitis, "puffy hand" syndrome, and lymphadenopathy. These complications usually present as urgent issues requiring prompt and accurate evaluation in the acute setting. Diagnostic imaging not only aids in making the correct diagnosis but also permits precise definition of the location and extent of these abnormalities. We review the imaging findings and illustrate a wide range of disabling and even life-threatening complications affecting the upper extremity of IVDA patients that require early diagnosis for optimal outcome.     

<Superscript>18</Superscript>F-FDG PET for the lymph node staging of non-small cell lung cancer in a tuberculosis-endemic country: <Emphasis Type="Italic">Is dual time point imaging worth the effort?</Emphasis>

PURPOSE: This study was to compare (18)F-FDG positron emission tomography (PET) with thoracic contrast-enhanced CT (CECT) in the ability of lymph node (LN) staging non-small cell lung cancer (NSCLC) in a tuberculosis-prevalent country. The usefulness of dual time point PET imaging (DTPI) in NSCLC nodal staging was also evaluated. METHODS: We reviewed 96 NSCLC patients (mean age, 65.3 +/- 11.7 years) who had received PET studies before their surgery. DTPI were performed on 37 patients (mean age, 64.8 +/- 12.2 years) who received an additional scan of thorax 3 h after tracer injection. The accuracies of nodal staging by CECT and PET were evaluated according to final histopathology of hilar and mediastinal LN resected by surgery. RESULTS: The accuracy for nodal staging by CECT was 65.6% and that by PET was 82.3% (p < 0.05). Six patients were over-staged and 11 were under-staged by PET. Tuberculosis (n = 3, 50%) were mostly responsible for false-positive, while small tumor foci (n = 7, 63.6%) were mostly accountable for false-negative. For the 37 patients with DTPI, 45 min standardized uptake value (SUV) and 3 h SUV for negative LNs are significantly lower than those for positive LNs (p < 0.0001). Nevertheless, the retention index (RI) showed no significant difference between these two groups. CONCLUSIONS: Our study demonstrates that PET is more accurate than CECT in LN staging NSCLC patients in Taiwan where TB is still prevalent. Semi-quantitative SUV method or DTPI with RI does not result in better diagnostic accuracy than visual analysis of PET images.     

Aortic injury with chance fracture in a child

To present the findings in a 10-year-old male with a Chance fracture and associated aortic vascular injury and review of the literature on the subject. We reviewed the clinical and imaging findings in a patient who was in a serious motor vehicle accident, sustaining a Chance fracture of the lumbar spine and associated aortic and common iliac vessel injury. We also accomplished a literature review. Evidence of an associated aortic injury was available on the initial computed tomography (CT) study, but the findings were more exquisitely demonstrated on reconstructed studies of the lumbar spine. Our literature review indicated that aortic injury associated with Chance fracture is relatively rare and often overlooked. Abdominal aortic injury although rare, can occur with Chance fractures. With the now present sophisticated CT imaging in most Emergency Rooms it is possible to obtain exquisite reconstructed images of all organ systems including the vascular tree. The images may provide enough details so that further delineation of any given problem may not be necessary.     

The effect of overlapping on the primary stability of osteochondral grafts in mosaicplasty

Our goal was to determine the primary stability of overlapping osteochondral grafts used in mosaicplasty by studying the effect of overlapping in an ex vivo model. Osteochondral grafts, 10 mm in diameter, were transplanted from the trochlea of cow femurs to the weight-bearing area of the lateral femoral condyle with 0, 15, or 30% overlap. The grafts were pushed in with a probe at a rate of 2 mm/min, and load (N)-displacement (mm) curves were recorded. In Group I (control, 0% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 572.3 +/- 273.6 and 999.3 +/- 427.6 N, respectively. In Group II (15% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 263.6 +/- 91.7 and 746.6 +/- 88.0 N, respectively. In Group III (30% overlap), insertion 1 and 2 mm below the cartilage level could be reached at 179.4 +/- 31.2 and 657.0 +/- 106.5 N, respectively. The loads that were necessary to produce a 1-mm dent in the grafts were significantly different between Groups I and II and Groups I and III (p < 0.05). These results suggest that stability may be reduced by graft overlapping in mosaicplasty surgery. The results of this ex vivo animal study contribute to a more complete understanding of the primary stability of osteochondral grafts in an overlapping position as well as postoperative protocols.     

<Superscript>68</Superscript>Ga- and <Superscript>111</Superscript>In-labelled DOTA-RGD peptides for imaging of αvβ3 integrin expression

PURPOSE: alphavbeta3 integrins are important cell adhesion receptors involved in angiogenic processes. Recently, we demonstrated using [(18)F]Galacto-RGD that monitoring of alphavbeta3 expression is feasible. Here, we introduce (68)Ga- and (111)In-labelled derivatives and compare them with [(18)F]Galacto-RGD. METHODS: For radiolabelling, cyclo(RGDfK(DOTA)) was synthesised using SPPS. For in vitro characterisation determination of partition coefficients, protein binding, metabolic stability, alphavbeta3 affinity and cell uptake and for in vivo characterization, biodistribution studies and micro positron emission tomography (PET) imaging were carried out. For in vivo and in vitro studies, human melanoma M21 (alphavbeta3 positive) and M21-L (alphavbeta3 negative) cells were used. RESULTS: Both tracers can be synthesised straightforward. The compounds showed hydrophilic properties and high metabolic stability. Up to 23% protein-bound activity for [(68)Ga]DOTA-RGD and only up to 1.4% for [(111)In]DOTA-RGD was found. Cell uptake studies indicate receptor-specific accumulation. This is confirmed by the biodistribution data. One hour p.i. accumulation in alphavbeta3-positive tumours was 2.9 +/- 0.3%ID/g and in alphavbeta3-negative tumours 0.8 +/- 0.1%ID/g for [(68)Ga]DOTA-RGD ([(111)In]DOTA-RGD: 1.9 +/- 0.3%ID/g and 0.5 +/- 0.2%ID/g; [(18)F]Galacto-RGD: 1.6 +/- 0.2%ID/g and 0.4 +/- 0.1%ID/g). Thus, tumour uptake ratios were comparable. Due to approx. 3-fold higher blood pool activities for [(68)Ga]DOTA-RGD, tumour/blood ratios were higher for [(111)In]DOTA-RGD and [(18)F]Galacto-RGD. However, microPET studies demonstrated that visualisation of alphavbeta3-positive tumours using [(68)Ga]DOTA-RGD is possible. CONCLUSIONS: Our data indicate that [(68)Ga]DOTA-RGD allows monitoring of alphavbeta3 expression. Especially, the much easier radiosynthesis compared to [(18)F]Galacto-RGD would make it an attractive alternative. However, due to higher blood pool activity, [(18)F]Galacto-RGD remains superior for imaging alphavbeta3 expression. Introduction of alternative chelator systems may overcome the disadvantages.     

<Superscript>18</Superscript>F-FDG PET/CT in sarcoidosis management: review and report of 20 cases

PURPOSE: To evaluate the interest of (18)F-fluoro-2-deoxy-D: -glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for diagnosis and therapeutic follow-up of patients with sarcoidosis. METHODS: Twenty consecutive patients with biopsy-proven sarcoidosis were retrospectively included, in particular, 13 and seven cases of thoracic and extra-thoracic sarcoidosis, respectively. All patients underwent (18)F-FDG PET/CT, and 12 of them also (67)Ga scintigraphy. Five patients were re-examined by (18)F-FDG PET/CT to assess response to corticosteroid (CS) treatment. RESULTS: Sensitivity of (18)F-FDG PET/CT in detecting active sarcoidosis localizations was determined considering only biopsy-proven sites. For thoracic, sinonasal, and pharyngo-laryngeal localizations, (18)F-FDG PET/CT sensitivity was 100%, 100%, and 80%, respectively. Overall sensitivity for all 36 biopsy-proven localizations improved from 78% to 87% after excluding skin involvement. Considering only the 12 patients who underwent both scintigraphic examinations, overall sensitivity of (67)Ga scintigraphy and (18)F-FDG PET/CT was 58% and 79%, respectively and improved to 67% and 86% after excluding all sites of skin involvement. To evaluate the efficacy of CS treatment, five enrolled patients underwent second (18)F-FDG PET/CT. Complete regression of all foci of pathological tracer uptake was showed in two cases, permitting CS withdrawal after 2 and 6 months. Improvement but incomplete regression of mediastino-pulmonary disease occurred in two patients treated with CS for 19 and 21 months. Disease progression was assessed in one patient treated with decreasing doses of CS during 16 months. CONCLUSION: (18)F-FDG PET/CT allows to obtain a complete morpho-functional cartography of inflammatory active localizations and to follow treatment efficacy in patients with sarcoidosis, particularly in atypical, complex, and multisystemic forms.     

Image quality on dual-source computed-tomographic coronary angiography

Multi-detector CT reliably permits visualization of coronary arteries, but due to the occurrence of motion artefacts at heart rates >65 bpm caused by a temporal resolution of 165 ms, its utilisation has so far been limited to patients with a preferably low heart rate. We investigated the assessment of image quality on computed tomography of coronary arteries in a large series of patients without additional heart rate control using dual-source computed tomography (DSCT). DSCT (Siemens Somatom Definition, 83-ms temporal resolution) was performed in 165 consecutive patients (mean age 64 +/- 11.4 years) after injection of 60-80 ml of contrast. Data sets were reconstructed in 5% intervals of the cardiac cycle and evaluated by two readers in consensus concerning evaluability of the coronary arteries and presence of motion and beam-hardening artefacts using the AHA 16-segment coronary model. Mean heart rate during CT was 65 +/- 10.5 bpm; visualisation without artefacts was possible in 98.7% of 2,541 coronary segments. Only two segments were considered unevaluable due to cardiac motion; 30 segments were unassessable due to poor signal-to-noise ratio or coronary calcifications (both n = 15). Data reconstruction at 65-70% of the cardiac cycle provided for the best image quality. For heart rates >85 bpm, a systolic reconstruction at 45% revealed satisfactory results. Compared with earlier CT generations, DSCT provides for non-invasive coronary angiography with diagnostic image quality even at heart rates >65 bpm and thus may broaden the spectrum of patients that can be investigated non-invasively.     

Accuracy of accelerated cine MR imaging at 3 Tesla in longitudinal follow-up of cardiac function

The ability of fast, parallel-imaging-based cine magnetic resonance (MR) to monitor global cardiac function in longitudinal exams at 3 Tesla was evaluated. Seventeen patients with chronic cardiac disease underwent serial cine MR imaging exams (n = 3) at 3 Tesla. Data were acquired in short-axis orientation using cine steady-state free precession (SSFP) with a spatial resolution of 2.5 x 1.9 mm(2) at 45 ms temporal resolution. Multislice imaging (three slices/breath-hold) was performed using TSENSE acceleration (R = 3) and standard single-slice cine (non-TSENSE) was performed at identical locations in consecutive breath-holds. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) and myocardial mass (MM) of both cine approaches were compared for individual time-points as well as for longitudinal comparison. TSENSE-cine did not show significant differences for EDV (2.6 ml; P = 0.79), ESV (2.2 ml; P = 0.81), EF (-0.3%; P = 0.95) and MM (2.4 g; P = 0.72) in comparison with non-TSENSE. Longitudinal ANOVA analysis did not reveal significant differences for any parameter, neither for non-TSENSE data (all P > 0.7) nor for TSENSE data (all P > 0.9). Multifactorial ANOVA showed non-significant differences (all P > 0.7) at comparable data variances. Data acquisition was significantly shortened using TSENSE. Threefold accelerated multislice cine at 3 Tesla allows accurate assessment of volumetric LV data and accurate longitudinal monitoring of global LV function at a substantially shorter overall examination time.     

Perfusion CT compared to H<Subscript>2</Subscript><Superscript>15</Superscript>O/O<Superscript>15</Superscript>O PET in patients with chronic cervical carotid artery occlusion

INTRODUCTION: The purpose of this study was to compare the results of perfusion computed tomography (PCT) with those of (15)O(2)/H(2) (15)O positron emission tomography (PET) in a subset of Carotid Occlusion Surgery Study (COSS) patients. MATERIALS AND METHODS: Six patients enrolled in the COSS underwent a standard-of-care PCT in addition to the (15)O(2)/H(2) (15)O PET study used for selection for extracranial-intracranial bypass surgery. PCT and PET studies were coregistered and then processed separately by different radiologists. Relative measurement of cerebral blood flow (CBF) and oxygen extraction fraction (OEF) were calculated from PET. PCT datasets were processed using different arterial input functions (AIF). Relative PCT and PET CBF values from matching regions of interest were compared using linear regression model to determine the most appropriate arterial input function for PCT. Also, PCT measurements using the most accurate AIF were evaluated for linear regression with respect to relative PET OEF values. RESULTS: The most accurate PCT relative CBF maps with respect to the gold standard PET CBF were obtained when CBF values for each arterial territory are calculated using a dedicated AIF for each territory (R (2) = 0.796, p < 0.001). PCT mean transit time (MTT) is the parameter that showed the best correlation with the count-based PET OEF ratios (R (2) = 0.590, p < 0.001). CONCLUSION: PCT relative CBF compares favorably to PET relative CBF in patients with chronic carotid occlusion when processed using a dedicated AIF for each territory. The PCT MTT parameter correlated best with PET relative OEF.