In vivo coronary lesion differentiation with computed tomography angiography and intravascular ultrasound as compared to optical coherence tomography

Background

In vitro studies have shown the feasibility of coronary lesion grading with computed tomography angiography (CTA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) as compared to histology, whereas OCT had the highest discriminatory capacity.

Positron-emission tomography CT to identify local recurrence in stage I lung cancer patients 1 year after stereotactic body radiation therapy

Purpose

To evaluate the diagnostic value of positron-emission tomography/computed tomography (PET/CT) in stage I lung cancer patients treated with stereotactic body radiation therapy (SBRT), who have suspicious or unclear local recurrence findings in CT 1 year after treatment.

Patients and methods

A group of 29 patients with unclear or suspicious CT findings 1 year after SBRT were examined with PET/CT. The ability of standard uptake values (SUV_max, SUV_mean and posttherapeutic reduction in SUV) to detect local failure and identify patients at a high risk of disease-specific death was evaluated using logrank statistics. Histology and clinical follow-up were the gold standards for local recurrence.

Results

SUV_mean greater than 3.44 (p?=?0.001); SUV_max greater than 5.48 (p?=?0.009) or a relative reduction in SUV_mean or SUV_max of less than 43 (p?=?0.030) or 52?% (p?=?0.025), respectively, was indicative of local recurrence. These parameters also correlated with an increased risk of disease-specific death: SUV_mean greater than 2.81 (p?=?0.023); SUV_max greater than 3.45 (p?=?0.007) or a relative reduction in SUV_mean or SUV_max of less than 32 (p?=?0.015) or 52?% (p?=?0.013), respectively, was indicative of an increased risk of disease-specific death.

Conclusion

PET/CT performed 1 year after SBRT can reliably identify local recurrence and therefore help to clarify unclear CT findings. As posttherapeutic glucose metabolism also correlates with disease-specific survival, PET/CT may help to stratify lung cancer patients for additional treatment 1 year after SBRT.     

Tumor lesion detection: when is integrated positron emission tomography/computed tomography more accurate than side-by-side interpretation of positron emission tomography and computed tomography?

OBJECTIVES: To determine if there is added value to oncology studies performed with a dedicated in-line positron emission tomography (PET)/computed tomography (CT) scanner as compared with PET read side by side with diagnostic CT (DCT). METHODS: Forty-one consecutive oncology patients referred for PET/CT who had contemporary DCT scans for review were enrolled. Body regions assessed on a DCT scan were assessed on PET/CT and by side-by-side reading of PET and DCT (SBS PET/DCT). Lesions identified on DCT, the CT portion of PET/CT, SBS PET/DCT, and the reading of fused PET/CT images were scored as benign or malignant. The PET portion of the PET/CT study was read by 2 teams: the first read the SBS PET/DCT scan and the other read the complete fused PET/CT scan. For discordant lesions, the final diagnosis was determined by pathologic findings (n = 6) or imaging follow-up (n = 21). RESULTS: Twenty-seven (16.1%) of the 168 lesions were discordant when comparing analysis of fused PET/CT and SBS PET/DCT. Sixteen (9.5%) were fundamentally discordant, and 11(6.6%) were discordant in degree of confidence. For all discordant lesions only, the sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for PET/CT were 100%, 33%, 100%, 94%, and 78%, respectively, and for SBS PET/DCT, they were 38%, 50%, 19%, 73%, and 30%, respectively (P < 0.001 for sensitivity, P = not specific for specificity). The 2 main causes for misclassification on SBS PET/DCT were incorrect localization (n = 12) and changes occurring in the time gap between DCT and PET/CT (n = 4). CONCLUSIONS: In-line PET/CT offers better lesion localization in comparison to the visual fusion of PET and CT, especially for small lymph nodes, lesions adjacent to mobile organs, or lesions adjacent to the chest or abdominal wall.     

FDG positron emission tomography/computed tomography studies of Wilms’ tumor

Purpose  

The purpose of this analysis was to evaluate the utility of FDG PET/CT scanning in patients with Wilms’ tumors.     

Contrast enhancement in multidetector-row computed tomography (MDCT) of the abdomen: intraindividual comparison of contrast media containing 300 mg versus 370 mg iodine per ml

The purpose of this study was to intraindividually evaluate the difference in intraluminal vessel and parenchyma contrast enhancement of two different iodine concentrations in multidetector-row computed tomography (MDCT) of the abdomen. Eighty-three patients underwent baseline and follow-up MDCT-scanning (Somatom Sensation 16; Siemens, Forchheim, Germany) of the abdomen using contrast media containing 370 mg iodine/ml (protocol A; Ultravist 370, Bayer Schering Pharma, Berlin, Germany) and 300 mg iodine/ml (protocol B; Ultravist 300). The total iodine load (37 g iodine) and the iodine delivery rate (1.29 g iodine/s) were identical for both protocols. Contrast enhancement in the portal venous phase was measured in the abdominal aorta, inferior vena cava, portal vein, liver, spleen, pancreas and kidney. Mean attenuation values were compared using paired t-test. Intraindividual comparison revealed no statistically significant differences of the mean attenuation values between protocols A and B for all anatomic sites: abdominal aorta, inferior vena cava, portal vein, liver, spleen, pancreas and kidney (all P > 0.05). Given an injection protocol with constant total iodine load and constant iodine delivery rate, the iodine concentration of contrast media does not significantly influence abdominal contrast enhancement in the portal venous phase.     

Evaluation of Wegener’s granulomatosis using 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Objective

Wegener’s granulomatosis (WG) is a relatively rare disease characterized by granulomatous necrotizing vasculitis that primarily involves small- and medium-sized vessels. Systemic findings observed on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) have not been well reported. The purpose of this study was to evaluate the FDG PET/CT imaging in the diagnosis and follow-up of patients with WG.

Materials and methods

Thirteen FDG PET/CT images obtained for 8 patients (2 men and 6 women) with WG were retrospectively analyzed. Of these, 6 were performed for diagnosis, 2 for restaging and follow-up, and 5 for assessment of treatment efficacy. Maximum standardized uptake values (max SUVs) and visual analyses were used to interpret the FDG PET/CT images. In addition, nonenhanced CT findings obtained during FDG PET/CT were described.

Results

WG lesions of the upper respiratory tract and lung were more clearly detected by FDG PET/CT fusion imaging than by nonenhanced CT alone, and all of the active lesions showed decreased FDG uptake after treatment. In addition, FDG PET/CT can provide complementary information to indicate biopsy site based on FDG uptakes.

Conclusions

FDG PET/CT is a feasible modality for evaluating lesion activities, therapeutic monitoring, and follow-up of WG. Furthermore, biopsy sites of WG lesions may be determined by FDG PET/CT.     

Is contrast material needed after treatment of malignant lymphoma in positron emission tomography/computed tomography?

Purpose  

Positron emission tomography (PET)/computed tomography (CT) with ¹⁸F-fluorodeoxyglucose is widely used for post-therapeutic surveillance of malignant lymphoma. Debate still exists as to whether intravenous contrast media during the CT stage of a PET/CT scan should be used. The purpose of this study was to investigate the clinical value of contrast agent in PET/CT in patients with lymphoma following treatment.     

Hepatic cavernous hemangiomas: long-term (&gt; 5 years) follow-up changes on contrast-enhanced dynamic computed tomography or magnetic resonance imaging and determinant factors of the size change

Purpose

To investigate the very long-term (> 5 years) follow-up changes of hepatic cavernous hemangiomas and to evaluate possible determinant factors for the changes.

Materials and methods

Among 1115 consecutive patients suspected of having hepatic hemangiomas based on imaging features, 101 patients with comparable computed tomography or magnetic resonance imaging data during a 5-year follow-up interval in the Picture Archiving and Communication System were analyzed. Two radiologists independently determined the largest dimension of each lesion on axial images. In addition to background liver fibrosis or steatosis on imaging, histories of use of chemotherapeutic agents were checked from the patients’ records. The final size change of the hemangioma was categorized into three groups compared with the initial diameter (increased, > 120%; no change, 80–120%; decreased, < 80%).

Results

Among the 101 hemangiomas, 32 lesions (31.7%) were enlarged and 21 lesions (20.8%) were shrunken during intervals of 60–157 (median, 81) months. Younger patients showed a higher prevalence of lesion enlargement (mean age: enlarged, 47.3 years; no change, 52.8 years; shrunken, 57.1 years; p = 0.003). In 15 patients with cirrhosis, the lesions (shrunken, n = 7; enlarged, n = 1) showed a higher tendency of size decrease (p = 0.009), whereas other factors did not show statistical significance (p > 0.05). Only a minor proportion (1%, n = 1) of the lesions showed size fluctuation during follow-up.

Conclusion

During the long-term (5–13 years) follow-up, about 50% of the hepatic hemangiomas were enlarged or shrunken to > 20% of the initial diameter. Aside from the cirrhosis and aging factors, the size changes seemed sporadic.

     

Benign or malignant?: differentiating breast lesions with computed tomography attenuation values on dynamic computed tomography mammography

OBJECTIVE: To evaluate enhancement effects of breast lesions with dynamic computed tomography (CT) and to determine characteristics to aid in differential diagnosis of benign and malignant lesions. METHODS: One hundred seventy-six women underwent preoperative dynamic CT, in which they were scanned with rapid injection of contrast media (3 mL/s) after 30 seconds and 2 minutes (early and delayed phases, respectively). The CT values and enhancement patterns of malignant lesions (n = 154) were compared with those of benign lesions (n = 22), and the cut point of CT values with the best validity was analyzed. RESULTS: The CT values of malignant lesions were higher than those of benign lesions in both phases (P < 0.0001). The cut point was determined to be 60 Hounsfield units (HU) in the early phase (44% validity, 90% sensitivity). Washout and plateau patterns were more commonly seen in the malignant group (73% specificity). CONCLUSIONS: The analysis of enhancement effects on CT may lead to more appropriate differentiation of benign and malignant lesions.     

A novel phantom design for emission tomography enabling scatter- and attenuation-”free” single-photon emission tomography imaging

A newly designed technique for experimental single-photon emission tomography (SPET) and positron emission tomography (PET) data acquisition with minor disturbing effects from scatter and attenuation has been developed. In principle, the method is based on discrete sampling of the radioactivity distribution in 3D objects by means of equidistant 2D planes. The starting point is a set of digitised 2D sections representing the radioactivity distribution of the 3D object. Having a radioactivity-related grey scale, the 2D images are printed on paper sheets using radioactive ink. The radioactive sheets can be shaped to the outline of the object and stacked into a 3D structure with air or some arbitrary dense material in between. For this work, equidistantly spaced transverse images of a uniform cylindrical phantom and of the digitised Hoffman rCBF phantom were selected and printed out on paper sheets. The uniform radioactivity sheets were imaged on the surface of a low-energy ultra-high-resolution collimator (4 mm full-width at half-maximum) of a three-headed SPET camera. The reproducibility was 0.7% and the uniformity was 1.2%. Each rCBF sheet, containing between 8.3 and 80 MBq of ^99mTcO₄ ^– depending on size, was first imaged on the collimator and then stacked into a 3D structure with constant 12 mm air spacing between the slices. SPET was performed with the sheets perpendicular to the central axis of the camera. The total weight of the stacked rCBF phantom in air was 63 g, giving a scatter contribution comparable to that of a point source in air. The overall attenuation losses were <20%. A second SPET study was performed with 12-mm polystyrene plates in between the radioactive sheets. With polystyrene plates, the total phantom weight was 2300 g, giving a scatter and attenuation magnitude similar to that of a patient study. With the proposed technique, it is possible to obtain ”ideal” experimental images (essentially built up by primary photons) for comparison with ”real” images degraded by photon scattering and attenuation losses. The method can serve as a tool for experimental validation and intercomparison of attenuation and scatter correction methods. Moreover, the large flexibility of this phantom design will allow investigations of arbitrary activity distributions and autoradiography or other imaging techniques such as PET, x-ray computed tomography or magnetic resonance imaging. Received 8 August and in revised form 21 September 1999     

Can fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography detect hepatocellular carcinoma and its extrahepatic metastases?

Aims

The point of this research is to investigate the potential role of (18-F-FDG/PET) in the identification of hepatocellular carcinoma (HCC) and its metastases.

Drowning—post-mortem imaging findings by computed tomography

The aim of this study was to identify the classic autopsy signs of drowning in post-mortem multislice computed tomography (MSCT). Therefore, the post-mortem pre-autopsy MSCT- findings of ten drowning cases were correlated with autopsy and statistically compared with the post-mortem MSCT of 20 non-drowning cases. Fluid in the airways was present in all drowning cases. Central aspiration in either the trachea or the main bronchi was usually observed. Consecutive bronchospasm caused emphysema aquosum. Sixty percent of drowning cases showed a mosaic pattern of the lung parenchyma due to regions of hypo- and hyperperfused lung areas of aspiration. The resorption of fresh water in the lung resulted in hypodensity of the blood representing haemodilution and possible heart failure. Swallowed water distended the stomach and duodenum; and inflow of water filled the paranasal sinuses (100%). All the typical findings of drowning, except Paltau’s spots, were detected using post-mortem MSCT, and a good correlation of MSCT and autopsy was found. The advantage of MSCT was the direct detection of bronchospasm, haemodilution and water in the paranasal sinus, which is rather complicated or impossible at the classical autopsy.     

Computed tomography��old ideas and new technology

Several recently introduced 'new' techniques in computed tomography--iterative reconstruction, gated cardiac CT, multiple-source, and dual-energy CT--actually date back to the early days of CT. We review the historic origins and evolution of these techniques, which may provide some insight into the latest innovations in commercial CT systems.     

Jagdgeschwader 27

Background

Assessment of bones, especially with respect to the question of species, individualization, gender and exposure time is an essential component of routine forensic work and involves recent as well as historical objects. Morphological and morphometric investigations allow at least a reasonable answer to these aspects; however, the identification of bones and skeletal findings often founders on a lack of knowledge of a presumed identity or methodological limitations. Findings can substantially contribute to an assessment of the historical context.

Objective

Based on the planned excavation of a Messerschmitt Bf 109, which according to contemporary witnesses crashed in 1945, the possibilities and limitations of forensic osteological expertise are illustrated.

Material and methods

The recovery of the aircraft wreck from earth contaminated by aviation fuel was carried by representatives of the German War Graves Commission (?Volksbund Deutsche Kriegsgräberfürsorge e. V.“). Subsequently, a forensic osteological assessment of skeletal fragments and evaluation of accompanying objects were carried out. Furthermore, chemical toxicological investigations of biological materials, accompanying objects and the surrounding environment as well as DNA analytical investigations on selected bones were carried out.

Results

The investigations showed these were parts of a young male skeleton with deformation of the ribs as well as fractures of the spine and extremities. The cause of death was consistent with a high speed trauma (aircraft crash) without recognizable heat damage. A complete DNA profile of a male person could be achieved, despite the skeletal parts being saturated with aviation fuel.

Conclusion

Despite many indications (e.g. identification tag, aircraft type, accompanying findings and DNA profile) and presumed identity, an identification could not be achieved due to a lack of reference materials. Noteworthy was the complete DNA profile despite, or perhaps because of, fuel-saturated bones.

     

Detection of simulated vertical root fractures; which is better multi-detector computed tomography or cone beam computed tomography?

Objectives

Multi-detector computed tomography (MDCT) and cone beam computed tomography (CBCT) were compared regarding their ability to detect vertical root fractures.

Infrared pupillography in routine police traffic checks

Background

In order to evaluate the ability of traffic participants to drive, standardized and objective measurement methods are needed. In recent analyses it was shown that pupil function is a significant indicator of being under the influence of substances acting on the central nervous system.

Objective

The aim of this study was to answer the question whether it is possible to detect if a person is under the influence of drugs or medication based on pupil function.

Material and methods

In total 121 subjects were exposed to different light stimuli and an infrared pupillographic investigation of the eyes was carried out. The study cohort consisted of 41 healthy test subjects and 80 subjects under the influence of drugs or medication. Several neural network models with different network architectures were trained in a learning group, further analyzed in a verification sample and most importantly tested in an independent test sample. Specificity, sensitivity, negative and positive predictive values as well as the percentage of correctly predicted subjects were analyzed. A 95?% confidence interval (CI) was included for all performance measurements.

Results

A neural network model was found which performed with a specificity of 91?% (95% CI, 78–98?%), sensitivity 90?% (95% CI, 81–96?%), negative predictive value 85?% (95% CI, 72–94?%), positive predictive value 94?% (95% CI, 86–98?%) and a correct prediction was made for 90?% (95% CI, 83–95?%) of the subjects.

Conclusion

The results of this study clearly show that infrared pupillography provides excellent discrimination between healthy subjects and persons under the influence of drugs or medication in this specific setting.