Routine use of modified CT Enterography in patients with acute abdominal pain

Fixed rate vs fixed injection duration in single-pass contrast-enhanced abdominal multi-detector CT: effects on vascular enhancement

OBJECTIVES

To evaluate the effects on vascular enhancement of either a fixed rate (FR) or a fixed injection duration (FID) in single-pass (SP) contrast-enhanced abdominal multi-detector CT (CE-MDCT).

METHODS

Ninety-nine (54 M; 45 F; aged 18-86 years) patients with nontraumatic acute abdomen underwent a SP CE-MDCT after i.v. injection of 1.7 cc/Kg of a nonionic iodinated contrast media (370 mgI/mL) performed with either a FR (2 cc/s; Group A) or a FID (55 s; Group B). In both groups, patients were further stratified according to total body weight (kg) as follows: 40-60 (L); 61-80 (M); 81-100 (H). Signal- (SNR) and contrast-to-noise ratios (CNR) were calculated for the liver and for both abdominal aorta (AA) and main portal vein (MPV). Statistical analysis was performed by Student t- or Chi-square test for continuous and categorical data, respectively, whereas post hoc analysis was performed by the Mann-Whitney test (P < .05).

RESULTS

There were no significant differences in demographic and physical characteristics between Group A (n = 50; 53 ± 20 years; BMI = 23.4 ± 4.4) and Group B (n = 50; 51 ± 17 years; BMI 22.7 ± 4.2). Whereas overlapping findings were observed in the M sub-groups (n = 40), SNR and CNR were significantly higher (P < .01) in Group B for both AA and MPV in the high (H) weight sub-groups (n = 20) while not significant differences were observed in the low (L) weight sub-groups (n = 40) despite a significantly lower injection rate (1.6 ± 0.2 cc/s, P < .01) in Group B.

CONCLUSION

A FID results in an overall better vascular enhancement than a FR in SP CE-MDCT.

ADVANCES IN KNOWLEDGE

Single-pass is an optimized contrast-enhanced abdominal CT protocol combining the benefits of vascular and visceral enhancement and characterized by a customized scan delay tailored around a monophasic contrast injection. In single-pass protocol, a fixed injection duration (55 s) results in an overall better vascular enhancement than a fixed rate (2 cc/s) and should be therefore regarded as the injection modality of choice.

To Fill or Not to Fill? - Value of the Administration of Positive Rectal Contrast for CT Evaluation of Diverticular Disease of the Colon

PURPOSE

 To assess the value of the administration of positive rectal contrast at CT in patients referred for suspected diverticular disease (DD) of the colon.

MATERIALS AND METHODS

 460 patients (253 male, 207 female; median age 62 years; interquartile range 24) with clinical suspicion of DD of the colon were included in this retrospective IRB-approved study. CT was performed with i. v. contrast only (n = 328, group M1), i. v. + positive rectal contrast (n = 82, group M2), neither i. v. nor rectal contrast (n = 32, group S1), or positive rectal contrast only (n = 19, group S2). Two readers in consensus evaluated all CT datasets concerning diagnosis of DD (yes/no) and categorized findings (classification of diverticular disease (CDD)). Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values for the diagnosis of DD were calculated for all groups, using either clinical follow-up (n = 335) or intraoperative findings (n = 125) as the reference standard. In patients undergoing surgery, radiological staging of DD was correlated with the histopathology (weighted Cohen-k).

RESULTS

 224 patients (48.7 %) were diagnosed with DD. The sensitivity, specificity, PPV, and NPV were as follows. Group M1 / M2: 92 %/92 %, 97 %/94 %, 96 %/96 %, 94 %/89 %, respectively; group S1 / S2: 94 %/86 %, 93 %/80 %, 94 %/92 %, 93 %/67 %, respectively. Radiological staging and histopathology correlated substantially in all groups (k = 0.748-0.861).

CONCLUSION

 Abdominal CT had a high sensitivity and specificity for the diagnosis of DD. Disease staging correlated well with the findings at surgery. Additional positive rectal contrast administration did not have a significant advantage and may therefore be omitted in patients with suspected DD.

KEY POINTS

· CT has a high sensitivity and specificity for diagnosis of DD.. · CT staging using the CDD algorithm correlates very well with surgery.. · Positive rectal contrast administration does not improve diagnosis and radiological staging..

CITATION FORMAT

· Meyer S, Schmidbauer M, Wacker FK et al. To Fill or Not to Fill? - Value of the Administration of Positive Rectal Contrast for CT Evaluation of Diverticular Disease of the Colon. Fortschr Röntgenstr 2021; 193: 804 - 812.

Assessment of a split-bolus computed tomographic enterography technique for simultaneous evaluation of the intestinal wall and mesenteric vasculature of dogs

OBJECTIVE

To investigate the diagnostic usefulness of split-bolus CT enterography in dogs.

ANIMALS

6 healthy Beagles.

PROCEDURES

CT enterography was performed in all dogs in a nonrandomized crossover study design involving 3 techniques: a dual-phase technique and 2 techniques involving splitting of the administered contrast agent dose (ie, split technique and split-bolus tracking technique). For the 2 techniques involving dose splitting (ie, split CT enterography), contrast agent was injected twice, with the first injection consisting of 60% of the total dose, followed by injection of the remaining 40%. Then, a single set of CT images was obtained when the arterial and venous phases matched (dual-phase and split techniques) or when enhancement of the abdominal aorta reached 100 HU (split-bolus tracking technique). Enhancement of the intestinal wall and mesenteric vessels was assessed qualitatively and quantitatively.

RESULTS

The total number of images required for interpretation was significantly lower for the split technique than for the dual-phase technique. The amount of time needed to complete CT enterography was significantly less for the split-bolus tracking technique than for the other 2 techniques. For all 3 techniques, adequate contrast enhancement of the mesenteric vessels and intestinal wall was achieved. The split technique provided contrast enhancement of the intestinal wall and mesenteric vessels similar to that provided with the dual-phase technique, whereas contrast enhancement of these structures was lowest for the split-bolus tracking technique.

CONCLUSIONS AND CLINICAL RELEVANCE

Split-bolus CT enterography at a contrast agent allocation ratio of 60:40 enabled simultaneous evaluation of the enhanced intestine wall and mesenteric vessels and yielded image quality similar to that of dual-phase CT enterography in healthy dogs.

Utility of virtual unenhanced images and split-bolus injection using spectral multidetector CT for the assessment of renal cell carcinoma conspicuity and radiation dose

OBJECTIVE

The aim of this study was to evaluate the radiation dose and renal cell carcinoma conspicuity with virtual unenhanced images and split-bolus injection from spectral multidetector CT (MDCT).

MATERIAL AND METHODS

This prospective study was approved by the Ethics Committee, and informed consent was obtained. Ninety suspected patients of renal cell carcinoma diagnosed by abdominal ultrasonography and CEUS were randomly divided into two groups by a radiographer. Patients of the first group underwent spectral MDCT with virtual unenhanced imaging and split-bolus injection, while patients in the second group underwent conventional unenhanced as well as tri-phasic enhanced CT. Group A (split-bolus spectral MDCT group): The contrast material was administered at a dose of 1.5 mL/kg body weight at a flow rate of 4 mL/s, with a ratio of 7 to 5 before the CT scan with an interval of 60 seconds. Virtual unenhanced images were generated using a standard three-material decomposition algorithm, and the best mono-energy (keV) was calculated to show the tumour, renal artery and renal vein. Group B (conventional tri-phasic enhanced CT group): the contrast agent was injected with a dose of 1.5 mL/kg body weight at a flow rate of 4 mL/s. The corticomedullary phase scanning was performed once the arterial CT value reached 100 HU; the nephrographic phase was scanned 60 seconds later. And the excretory phase was scanned 5 min after onset of contrast injection. The LKR (lesion kidney ratio), CNR, and CT value of the corticomedullary and nephrographic phase were measured. The opacification of the renal collection system (including calices, infundibula and renal pelvis) was scored. The radiation dose was recorded. Statistical analysis was performed using Student's t-test, Fisher's exact test, the Mann-Whitney U-test, and k statistics.

RESULTS

There were no statistically significant differences between the two groups in age, sex and body mass index (BMI), but there was significant difference in treatment methods. The best mono-energy was 58 keV for showing the tumour and renal artery and 67 keV for showing the renal vein. There were no differences in the mean attenuations of normal renal parenchyma, renal tumour, CNR, and imaging quality between true unenhanced images and virtual unenhanced images from the combined corticomedullary and nephrographic phase. The LKR of the mono-energy at 58 keV from the combined corticomedullary and nephrographic phase was significantly better than the corticomedullary phase of the conventional enhanced CT scan (0.74±0.18 vs 1.08±0.34, P<.01), but there was no difference in CNR (2.31±1.74 vs 2.79±1.83, P>.05). There were no differences in the CT values of the renal tumour, normal renal parenchyma and renal artery between the two groups (P>.05). The CT value of the renal vein at mono-energy (67 keV) (200.55±43.38) from the combined corticomedullary and nephrographic phase was higher than the conventional CT scan (140.90±42.64) in the nephrographic phase. The Kappa scores of the rate of the renal collection system for the conventional CT and spectral CT were 0.68 (95% confidence interval [CI]: 0.35-0.89) and 0.54 (95% CI: 0.30-0.88), respectively. The radiation dose (735±162 mGy·cm) of Group A was significantly less than that of Group B (1032±324 mGy·cm) (P<.01).

CONCLUSION

Conspicuity with virtual unenhanced imaging and split-bolus injection from spectral multidetector CT is better than or equal to the conventional three-phase enhanced CT scan in showing the RCC, renal artery and renal vein, while the radiation dose can be reduced by 28.78%.

Imaging acute complications in cancer patients: what should be evaluated in the emergency setting?

Increased incidence world-wide of cancer and increased survival has also resulted in physicians seeing more complications in patients with cancer. In many cases, complications are the first manifestations of the disease. They may be insidious and develop over a period of months, or acute and manifest within minutes to days. Imaging examinations play an essential role in evaluating cancer and its complications. Plain radiography and ultrasonography (US) are generally performed initially in an urgent situation due to their wide availability, low cost, and minimal or no radiation exposure. However, depending on a patient's symptoms, evaluation with cross-sectional imaging methods such as computed tomography (CT) and magnetic resonance imaging (MRI) is often necessary. In this review article, we discuss some of the most important acute noninfectious oncological complications for which imaging methods play an essential role in diagnosis.

CT virtual colonoscopy in displaying excavated colon lesions

The aim of this study was to evaluate the relative values of 2D plane view and 3D intracavity view of CT virtual colonoscopy in displaying colon excavated lesions. Cleaned porcine colon with ulcerative lesion was scanned with multidetector CT. The data were reconstructed and reviewed using 2D plane view and 3D volume-rendered images on a GE AW4.2 workstation. The 3D volume-rendered images showed superiority in displaying excavated lesions.

CT enterography

Conventional radiologic and endoscopic evaluations of the small bowel are often limited by the length, caliber, and motility of the small bowel loops. The development of new multidetector-row CT scanners, with faster scan times and isotropic spatial resolution, allows high-resolution multiphasic and multiplanar assessment of the bowel, bowel wall, and lumen. CT Enterography (CTE) is a variant of routine abdominal scanning, geared toward more sustained bowel filling with oral contrast material, and the use of multiplanar images, that can enhance gastrointestinal (GI) tract imaging. This article examines the techniques and clinical applications of CTE in comparison with CT enteroclysis, focusing on Crohn disease, obscure GI bleeding, GI tumors, acute abdominal pain, and bowel obstruction.

Assessment of appropriateness of indications for CT enterography in younger patients

BACKGROUND

The small potential risk of radiation-induced cancer is increased in younger patients undergoing serial imaging with computed tomography enterography (CTE). We sought to determine the appropriateness of CTEs based on clinical indication in patients < or =35 years old, and the potential impact of evolution of practice to alternative magnetic resonance enterography (MRE).

METHODS

Over a 7-year period, the medical records of all patients < or =35 years old undergoing CTE were reviewed to determine the clinical indications for each CTE exam. An interdisciplinary consensus panel evaluated the appropriateness of all CTE exams based on American College of Radiology appropriateness criteria and peer-reviewed literature, classifying indications into "appropriate" or "inappropriate." For repeat CTEs, an "alternative MRE suggested" pathway was created. Criteria for evolution of practice to "alternative MRE" were suspicion of obstruction and evaluation of disease activity/therapeutic response in the absence of new symptoms.

RESULTS

In all, 2022 patients < or =35 years old underwent 2295 CTEs. Ninety-nine percent (2008/2022) of first-time CTE exams were "appropriate" by the defined criteria. A total of 197 patients (9.7%) underwent multiple exams, with 73% of these patients having Crohn's disease. Repeat exams occurred in 9% (18/197) with obstructive symptoms and evaluation of disease activity/therapeutic response in the absence of new symptoms in 41% (80/197).

CONCLUSIONS

A multidisciplinary expert panel concluded that the vast majority of young patients underwent clinically appropriate first-time CTE exams. However, a shift in clinical practice to MRE appears warranted for approximately half of young patients undergoing repeat CTE examinations.

CT enterography of Crohn's disease

CT enterography (CTE) is a technique using neutral oral contrast, intravenous contrast and thin cut, multiplanar CT acquisitions to optimize small bowel imaging. One of the primary indications for CTE is the detection and evaluation of Crohn's disease. This article summarizes the advantages/disadvantages, scanning technique, imaging findings, performance and pitfalls of CTE for the evaluation of Crohn's disease.