Computed tomographic colonography (CTC): Possibilities and limitations of clinical application in colorectal polyps and cancer.

Colorectal cancer is the second leading cause of cancer-related deaths in Europe and the United States. Most colorectal cancers develop from adenomatous polyps over a number of years. Early detection of polyps eliminates the risk of subsequent carcinomas. Computed tomographic (CT) colonography is a diagnostic technique detecting colorectal neoplasms. With the introduction of multidetector-row computed tomography (MD-CT), CT colonography (CTC) has gained influence as a new diagnostic tool in early detection of colonic pathologies by acquiring volumetric CT data sets of the abdomen. This volumetric data is analyzed using CTC workstations, which provide an interactive display of 2D and 3D images of the colon. In several studies, CTC revealed a high accuracy (sensitivity/patient: 83-100% and specificity/patient: 93-100%) in detecting pathological colonic changes. Furthermore, CTC is an excellent diagnostic technique for the evaluation of patients with incomplete conventional colonoscopy and allows the assessment of extracolonic abdominal and pelvic organs. In this article, the status of CT colonography as a method of detecting colonic polyps and colorectal carcinomas using single- and multidetector-row CT will be reviewed.

Comparison of volume-rendered and surface-rendered MR colonography.

In the United States and Europe, colorectal cancer is the second leading cause of cancer-related deaths. It is well known that colorectal carcinomas may originate from preexisting adenomas. For the visualization of colorectal cancer and other pathologic changes such as polyps, two 3D methods (volume-rendering (VR) and surface-rendering (SR)) in MR colonography were compared in our study. MR colonography was carried out in 17 patients on a 1.5 T MR scanner using a 10 mmolar gadolinium water solution enema. Coronal as well as rotated VR and SR views were compared in order to examine the technical quality (TQ) of the visualization model and grade of confidence (GC) in the pathological findings. Colonoscopic findings revealed 8 colorectal carcinoma, 10 patients with polyps, 4 diverticular disease, and 2 with redundant bowel loops. Based on a total of 248 colonic segments for both visualization methods, volume rendering were significantly superior to surface rendering for both, TQ (p<0.0001) and GC (p<0.0001). Volume rendering and surface rendering were not dependent on individual colon segments (p=0.13 for TQ and p=0.18 for GC) or on image rotation (p=0.06 for TQ and p=0.062 for GC). It is also independent of the type of pathology (p=0.31 for TQ and p=0.42 for GC) and the reviewers (p=0.62 for TQ and p=0.88 for GC). This indicates, that for the purpose of interpreting the technical quality and pathological findings, volume rendering is superior to surface rendering in MR colonography. Volume rendering could be used as an 3D visualization tool, enabling MR colonography examinations to be completed sooner in cases where colon distension is sufficient, and it would also provide an overview of potential mass lesions.

Economic value of thrombolysis with adjunctive abciximab in patients with subacute peripheral arterial occlusion.

BACKGROUND AND OBJECTIVE: Glycoprotein (GP) IIb/IIIa receptor inhibitors enhance thrombolysis in patients with acute coronary syndromes. This analysis evaluates the economic impact of abciximab, a GP IIb/IIIa inhibitor, as an adjunct to urokinase in peripheral artery occlusions of less than 6 weeks duration. STUDY DESIGN: A post-hoc economic analysis was performed using clinical data and inpatient resource utilisation derived from the prospective comparative phase II Platelet Receptor Antibodies in Order to Manage Peripheral Artery Thrombosis (PROMPT) pilot study. Study endpoints were amputation-free survival and survival without open surgery or major amputation after 90 days, and the rate of major complications at 30 days. PERSPECTIVE: Third-party payer and the societal perspective. PATIENTS AND METHODS: Seventy patients with lower extremity thrombi were randomised (2 : 5 ratio) to urokinase plus placebo or to urokinase plus abciximab. Economically relevant data were retrospectively derived from the clinical study database from a specific evaluation of patient records and from expert opinion. RESULTS: From the viewpoint of the society, average total per-patient direct and indirect costs accruing over 3 months were more favourable for treatment with abciximab plus urokinase than for urokinase alone [9723 euros (EUR) vs EUR10 322; 2000 values], despite higher initial hospitalisation costs of the combination therapy. Abciximab plus urokinase was the dominant strategy at 3 months due to a clinically higher rate of survival without amputation or bypass surgery coupled with a lower average per-patient cost. From the perspective of the third-party payer, treatment with abciximab plus urokinase was economically also superior to urokinase alone (EUR8773 vs EUR9663). CONCLUSIONS: Based on the preliminary findings of the PROMPT trial, the use of abciximab as an adjunct to urokinase in patients with subacute peripheral artery occlusions may be the favourable strategy compared with urokinase alone, in terms of clinical and economic outcomes. Further trials are needed to confirm these clinical and economic findings. The preliminary clinical benefits experienced by patients treated with abciximab plus urokinase in the PROMPT trial translated into cost savings in terms of reduced direct medical costs at 3 months. These cost savings more than offset the cost of abciximab. The use of abciximab as an adjunct to urokinase in patients with subacute peripheral artery occlusions may be the favourable strategy compared with urokinase-alone in terms of clinical and economic outcomes, but further trials are needed to confirm the these clinical and economic findings.

Assessment of T1, T1ρ, and T2 values of the ulnocarpal disc in healthy subjects at 3 tesla.

OBJECTIVE: The purpose of this study was to implement clinically feasible imaging techniques for determination of T1, T1ρ, and T2 values of the ulnocarpal disc and to assess those values in a cohort of asymptomatic subjects at 3 tesla. Resulting values were compared between different age groups, since former histological findings of the ulnocarpal disc indicated frequent early degenerative changes of this tissue starting in the third decade of life, even in asymptomatic subjects. MATERIALS AND METHODS: Twenty-seven healthy subjects were included in this study. T1 measurements were performed using 3D spoiled gradient-echo (GRE) sequence with variable flip angle. A series of T1ρ and T2-weighted images was acquired by a 3D GRE sequence after suitable magnetization preparation. T1,T1ρ, and T2 maps of the ulnocarpal disc were calculated pixel-wise. Representative mean values from extended regions were analysed. RESULTS: Mean T1 values of the ulnocarpal disc ranged from 722 ms in a 39 year-old subject to 1264 ms in a 65 year-old subject, T1ρ ranged from 9.2 ms (26 year-old subject) to 25.9 ms (65 year-old subject). Calculated T2 values showed a large range from 4.1 ms to 22.3 ms. T1ρ and T1 values tended to increase with age (p<0.05), whereas T2 did not. CONCLUSIONS: MR relaxometry of the ulnocarpal disc is feasible, and T1,T1ρ, and T2 values show modest variance in asymptomatic subjects. The potential of relaxation mapping to reveal relevant structural changes in patients has to be investigated in further studies.

Single-source dual-energy computed tomography: use of monoenergetic extrapolation for a reduction of metal artifacts.

OBJECTIVES: The objective of this study was to retrospectively determine the potential of virtual monoenergetic (ME) reconstructions for a reduction of metal artifacts using a new-generation single-source computed tomographic (CT) scanner. MATERIALS AND METHODS: The ethics committee of our institution approved this retrospective study with a waiver of the need for informed consent. A total of 50 consecutive patients (29 men and 21 women; mean [SD] age, 51.3 [16.7] years) with metal implants after osteosynthetic fracture treatment who had been examined using a single-source CT scanner (SOMATOM Definition Edge; Siemens Healthcare, Forchheim, Germany; consecutive dual-energy mode with 140 kV/80 kV) were selected. Using commercially available postprocessing software (syngo Dual Energy; Siemens AG), virtual ME data sets with extrapolated energy of 130 keV were generated (medium smooth convolution kernel D30) and compared with standard polyenergetic images reconstructed with a B30 (medium smooth) and a B70 (sharp) kernel. For quantification of the beam hardening artifacts, CT values were measured on circular lines surrounding bone and the osteosynthetic device, and frequency analyses of these values were performed using discrete Fourier transform. A high proportion of low frequencies to the spectrum indicates a high level of metal artifacts. The measurements in all data sets were compared using the Wilcoxon signed rank test. RESULTS: The virtual ME images with extrapolated energy of 130 keV showed significantly lower contribution of low frequencies after the Fourier transform compared with any polyenergetic data set reconstructed with D30, B70, and B30 kernels (P < 0.001). CONCLUSIONS: Sequential single-source dual-energy CT allows an efficient reduction of metal artifacts using high-energy ME extrapolation after osteosynthetic fracture treatment.

Transketolase-like protein 1 expression in recurrent oral squamous cell carcinoma after curative resection: a case report.

BACKGROUND: Squamous cell carcinoma of the oral cavity (OSCC) is one of the common malignant tumors of the head and neck worldwide. Transketolase-like protein 1 (TKTL1), which has an important role in controlling the nonoxidative pentose-phosphate pathway, is significantly overexpressed in several different tumor entities. TKTL1 overexpression confers an advantage on malignant cells, allowing them to grow faster and to metastasize. However, to date, there is no link between TKTL1 expression and (metastatic) OSCC. CASE REPORT: We report the first case of simultaneous penile, lung, bone, and suprarenal gland metastases from a primary bifocal moderately differentiated keratinized OSCC in a 53-year-old man that occurred 7 months after primary diagnosis. The tumor stained positive for TKTL1, epithelial growth factor receptor, and cyclooxygenase-2 (COX-2). To the best of our knowledge, no case has been reported to date on the manifestation of synchronous distant metastases of OSCC in the penile and the suprarenal gland. CONCLUSIONS: Secondary malignancy of the penis is an uncommon clinical entity. Because of the possibility of penile metastatic spread, this case report suggests that particular attention should be paid to physical examination of patients who undergo surgical procedures from OSCC, including those seemingly without metastatic disease. For the first time, our case provides evidence that TKTL1 expression in recurrent OSCC might be associated with tumor formation and metastasis. Antibodies, small molecules, COX-2 inhibitors, or a ketogenic diet might be promising for therapy of metastatic OSCC.

Critical analysis of causality between negative ulnar variance and Kienböck disease.

BACKGROUND: Negative ulnar variance has been associated with Kienböck disease, both supporting a causal link and providing a basis for therapeutic recommendations. The aim of this study was to determine whether there is a causal relationship between Kienböck disease and negative ulnar variance. METHODS: The causal relationship between Kienböck disease and negative ulnar variance was assessed using three methodologies: (1) an analysis of the quantitative and qualitative distribution of ulnar variance in a case-control study of 81 patients with Kienböck disease and a control group of 212 healthy wrists; (2) a systematic literature review and meta-analysis of six case-control studies (including the case-control study presented in this article) to test for an association between Kienböck disease and negative ulnar variance; and (3) a determination of causal relationship by using the Bradford Hill criteria. RESULTS: The case-control study indicated that when Kienböck disease is associated with negative ulnar variance (59 of 81), in 75 percent of the cases negative ulnar variance was equal (29 of 59) or less (15 of 59) pronounced on the contralateral healthy side. The odds ratio generated from the meta-analysis demonstrated a significant association between Kienböck disease and negative ulnar variance (OR, 3.58; 95 percent CI, 1.59 to 8.06; p = 0.002, random effects method). Six of nine Bradford Hill criteria do not support a causal relationship. CONCLUSIONS: The significant association between Kienböck disease and negative ulnar variance can be well explained by selection bias because magnetic resonance imaging, which may detect and allow exclusion of a potential ulnar impaction syndrome, was performed in only the Kienböck disease group in all six case-control studies. The application of the Bradford Hill criteria does not provide sufficient scientific evidence to support a causal relationship between Kienböck disease and negative ulnar variance. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

A combined anatomical and clinical study for quantitative analysis of the microcirculation in the classic perfusion zones of the deep inferior epigastric artery perforator flap.

BACKGROUND: The establishment of the perfusion zones for the deep inferior epigastric artery perforator (DIEP) flap is still under debate. Specifically, differences between clinical and anatomical studies have often been described. The purpose of this combined study was to evaluate the characteristics of a DIEP zoning in both clinical and anatomical settings by quantitatively assessing the perfusion dynamics and vascular anatomy. METHODS: In the first part of the study, the perfusion dynamics of 16 patients undergoing DIEP flap breast reconstruction were assessed, determining cutaneous oxygen supply and blood flow using an Oxygen to See device. In the second part of the study, 11 flaps were harvested from fresh female cadavers. All specimens were subjected to dynamic computed tomographic scanning to simulate single-perforator DIEP flaps. RESULTS: The perfusion dynamics of DIEP flaps show no significant difference (p ≤ 0.05) between the two immediately adjacent zones, regardless of the use of lateral or medial perforator rows. However, use of the cadaver medial row perforator more often illustrated a vascular pattern across the midline (zone II, 86.4 percent) as compared with the lateral row-perfused DIEP flap. CONCLUSIONS: The authors' combined study showed varying perfusion characteristics between anatomical and clinical settings, which could be caused by a number of complex systemic and local processes. Thus, the selection of the DIEP zones should be assessed individually depending on the anatomy in question and the characteristics of the perforators until the mentioned issues are clarified in detail.

CASE REPORT Bilateral Paradoxically Symptomatic Luno-triquetral Coalition: A Case Report.

OBJECTIVE: While bony luno-triquetral coalitions are known to be asymptomatic, fibro-cartilage unions can cause ulnar-sided wrist pain. The purpose of this case report is to present a paradox clinical constellation of bilateral luno-triquetral coalition. Furthermore, recommendations for proper diagnosis and treatment options will be discussed. METHODS: The case of a 21-year-old female patient is reported, where a bony coalition of one side caused wrist pain and the contralateral fibro-cartilage bonding was asymptomatic. RESULTS: Because of the stable bony coalition in the symptomatic wrist, we refused to undertake a luno-triquetral fusion and continued conservative treatment with the option of wrist denervation. CONCLUSIONS: Consequently, not only incomplete but also complete luno-triquetral coalitions can cause wrist pain. Unfortunately, no clear biomechanical explanation is available for this finding.

Evaluation of various image reconstruction parameters in lower extremity stents using multidetector-row CT angiography: initial findings.

Image quality, visible lumen and patency of lower limb stents was assessed by multidetector-row computed tomography (MDCT) angiography using various reconstruction parameters and the results compared with conventional angiography. Fourteen patients (25 stents) were evaluated. From MDCT datasets, axial and coronal oblique reformations were reconstructed using differing reconstruction parameters (slice thickness, kernel, views). Artifacts and image quality were assessed using a five-degree scale (1=excellent, 5=poor). Visible stent diameter was measured. Stenosis severity was compared with calibrated catheter angiography. The image quality of medium and sharp image kernels were good/fair (1.9-2.4), while smooth kernel provided only acceptable/poor image quality (3.9-4.4). Coronal oblique images were rated superior to assess in-stent lumen rather than axial. Using medium and sharp kernels, the visible stent lumen was significantly greater than using smooth kernel (P<0.001). thirteen out of fourteen patients (24/25 stents) were correctly classified as patent. In one patient, in-stent stenosis (> or =50%) was falsely diagnosed using CT angiography (CTA) with smooth kernel and was, therefore, rated as false positive. Coronal oblique views, as well as medium and sharp kernels, have shown the best results regarding image quality to assess stent patency in the lower limb. Therefore, MDCT could be a valuable non-invasive modality for stent imaging in the peripheral vasculature.

Detection of pulmonary embolism using 16-slice multidetector-row computed tomography: evaluation of different image reconstruction parameters.

OBJECTIVE: To compare different image reconstruction parameters for detecting emboli of the pulmonary arteries according to anatomic levels using 16-slice multidetector-row computed tomography in patients suspected of having an acute pulmonary embolism (PE). METHODS: Sixty-two patients (33 male and 29 female) with a clinically suspected acute PE were included in the present study. Multidetector-row computed tomography scans were performed using 16-mmx0.75-mm collimation. Based on the computed tomography data set, different image reconstruction parameters were used for each patient: axial slice thicknesses (STs) of 0.75, 2, 4, and 6 mm; axial maximum intensity projection (MIP) STs of 4 mm; and coronal STs of 2 and 4 mm. In joint reading fashion, 2 experienced radiologists reviewed examination findings regarding the presence and/or absence of a PE. The reference standard for visualization and detection of PEs was defined using the axial images with a 0.75-mm ST. RESULTS: In 23 of 62 patients, a PE was diagnosed. For main and lobar pulmonary arteries, the sensitivities and specificities were as follows: axial 2-mm images, 1.0/1.0; axial 4-mm images, 1.0/1.0; axial 6-mm images, 0.97/0.99; MIP 4-mm images, 0.95/0.99; coronal 2-mm images, 1.0/1.0; and coronal 4-mm images, 1.0/1.0. Regarding segmental and subsegmental pulmonary arteries, sensitivity and specificity varied: axial 2-mm images, 0.97/1.0; axial 4-mm images, 0.81/0.99; axial 6-mm images, 0.65/0.99; axial MIP 4-mm images, 0.63/0.99; coronal 2-mm images, 0.91/0.99; and coronal 4-mm images, 0.74/0.99. CONCLUSIONS: In detecting segmental and subsegmental PEs, only the axial images with an ST of 2 mm proved to have results comparable with the axial 0.75-mm images. Therefore, thin-slice collimation and ST are mandatory for visualization of segmental and subsegmental PEs in patients suspected of having an acute PE.

Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast.

Automation in colorectal mass detection is achieved as soon as the voxels representing colorectal masses can be automatically segmented. We tested the Hounsfield (HU) value in intensely contrast enhanced high-resolution CT colonography for automated segmentation of colorectal masses in 18 patients with 35 polyps (28 < 10 mm, 7 > or = 10 mm) and 7 carcinomas. Mean HU values of the colonic wall and masses were determined to deduce a gradient threshold for a segmentation process, which encodes the voxels bordering the colonic lumen with a colour ranging in intensity from 0 to 100% according to the selected gradient threshold range in the volume rendering. The results of the automated segmentation process were superimposed on a virtual double contrast and endoscopic display and validated through correlation with morphology. Mean HU values and their standard deviations for the colonic wall, polyps < 10 mm, polyps > or = 10 mm and carcinomas were 63 +/- 24, 154 +/- 38, 116 +/- 41 and 108+/-29 HU, respectively. A gradient threshold ranging from 90 to 160 HU resulted in colour pools in 6 of 7 of polyps > or = 10 mm, and 6 of 7 carcinomas that were significant enough to prospectively guide the reader's attention to these masses. Due to the superposition of "false-positive" voxels in the projection view, the virtual endoscopic perspective was superior to the virtual double contrast display for controlling the segmentation results. The HU value is promising for automated segmentation of colorectal masses but needs to be combined with morphological parameters to render automated colorectal mass detection more accurate. Further refinements of the method with subsequent analysis of its accuracy, as well as analogue studies with contrast-enhanced MRI, appear warranted. More information at http://www.multiorganscreening.org