Halved contrast medium dose in lower limb dual-energy computed tomography angiography-a randomized controlled trial.

OBJECTIVES: To compare vascular attenuation (VA) of an experimental half iodine-load dual-layer spectral detector CT (SDCT) lower limb computed tomography angiography (CTA) with control (standard iodine-load conventional 120-kilovolt peak (kVp) CTA). METHODS: Ethical approval and consent were obtained. In this parallel RCT, CTA examinations were randomized into experimental or control. Patients received 0.7 vs 1.4 mL/kg of iohexol 350 mgI/mL in the experimental- vs the control group. Two experimental virtual monoenergetic image (VMI) series at 40 and 50 kiloelectron volts (keV) were reconstructed. PRIMARY OUTCOME: VA. SECONDARY OUTCOMES: image noise (noise), contrast- and signal-to-noise ratio (CNR and SNR), and subjective examination quality (SEQ). RESULTS: A total of 106 vs 109 were randomized and 103 vs 108 were analyzed in the experimental vs, control groups, respectively. VA was higher on experimental 40 keV VMI than on control (p < 0.0001), but lower on 50 keV VMI (p < 0.022). Noise was higher on experimental 40 keV VMI than on control (p = 0.00022), but lower on 50 keV VMI (p = 0.0033). CNR and SNR were higher than the control on experimental 40 keV VMI (both p < 0.0001) and 50 keV (p = 0.0058 and p = 0.0023, respectively). SEQ was better on both VMIs in the experimental group than in the control (both p < 0.0001). CONCLUSIONS: Half iodine-load SDCT lower limb CTA at 40 keV achieved higher VA than the control. CNR, SNR, noise, and SEQ were higher at 40 keV, while 50 keV showed lower noise. CLINICAL RELEVANCE STATEMENT: Spectral detector CT with low-energy virtual monoenergetic imaging performed halved iodine contrast medium (CM) lower limb CT-angiography with sustained objective and subjective quality. This facilitates CM reduction, improvement of low CM-dosage examinations, and examination of patients with more severe kidney impairment. TRIAL REGISTRATION: Retrospectively registered 5 August 2022 at clinicaltrials.gov NCT05488899. KEY POINTS: • Contrast medium dosage may be halved in lower limb dual-energy CT angiography with virtual monoenergetic images at 40 keV, which may reduce contrast medium consumption in the face of a global shortage. • Experimental half-iodine-load dual-energy CT angiography at 40 keV showed higher vascular attenuation, contrast-to-noise ratio, signal-to-noise ratio, and subjective examination quality than standard iodine-load conventional. • Half-iodine dual-energy CT angiography protocols may allow us to reduce the risk of PC-AKI, examine patients with more severe kidney impairment, and provide higher quality examinations or salvage poor examinations when impaired kidney function limits the CM dose.

Indirect CT venography of the lower extremities: impact of scan delay and patient factors on contrast enhancement and examination quality.

OBJECTIVES: Indirect computed tomography venography (CTV) is often the next imaging modality for deep vein thrombosis (DVT) when sonography is inconclusive. Our aim was to investigate the impact of scan delay and patient factors on contrast enhancement (CE) and examination quality in CTV. METHODS: Patients with clinical suspicion or clinical mimics of DVT in one large hospital were enrolled. Age, sex, body weight, height, heart rate, systolic blood pressure and cardiac output were registered. CTV of the popliteal veins was obtained at 30 s intervals at 30-210 s delays. The proportions of examinations with CE exceeding predefined cut-offs were estimated and subjective examination quality was rated. Changes in CE with time, and associations between patient factors and time to peak contrast enhancement (TPCE) were modelled with mixed effects non-linear and linear regression, respectively. RESULTS: The CE increased with increasing scan delay and reached a plateau from 120 to 210 s. The percentages of examinations achieving enhancement above cut-offs across all thresholds from 70 to 100 HU were higher at 120 s compared to 90 s (p < 0.001). After 120 s, there were no differences across scan delays for any thresholds. No patient factors showed a significant effect on TPCE. The percentage of examinations rated as acceptable was higher at 120 s compared to 90 s (p < 0.001). After 120 s, there were no statistically significant differences across scan delays. CONCLUSIONS: No patient factors were associated with TPCE in CTV. A fixed scan delay of 120-210 s yielded the best examination quality. KEY POINTS: • Contrast enhancement reached a plateau at scan delay between 90 and 120 s. • A scan delay of 120-210 s yielded the best examination quality. • No patient factors were associated with time to peak contrast enhancement.

Does prophylactic inferior vena cava filter reduce the hazard of pulmonary embolism and mortality in severe trauma? A single center retrospective comparative study.

OBJECTIVES: Use of inferior vena cava (IVC) filters in patients following severe trauma without recent history of venous thromboembolism (VTE) is controversial. Our objective was to determine if IVC filter placement in the setting of severe trauma effects the hazard of in-hospital pulmonary embolism (PE), deep venous thrombosis (DVT) and mortality. METHODS: This retrospective study recruited patients from a single Level I Trauma Center between 1/2008 and 12/2013. Inclusion criteria were age>15 years, Injury Severity Score (ISS)>15 and survival>24 h after hospital admission. Patients with VTE diagnosed prior to IVC filter placement were excluded. A Cox proportional hazards regression model was used, adjusting for immortal time bias with landmark analysis at predefined time after injury. Differences between IVC filter and non-IVC filter groups were adjusted using propensity score. RESULTS: In total 1451 patients were reviewed; 282 patients received an IVC filter and 1169 patients had no IVC filter placed. The mean age was 45.9 vs. 56.9 years and the mean ISS was 29.8 vs. 22.6 in the IVC filter and the non-IVC filter group, respectively. IVC filter placement was not associated with the hazard of PE (HR = 0.46; 95 % CI, 0.12,1.70; P = 0.24) or mortality (HR = 1.02; 95 % CI 0.60,1.75; P = 0.93). However, IVC filter placement was associated with the hazard of DVT (HR = 2.73; 95 % CI, 1.28,5.85; P = 0.01). CONCLUSIONS: In patients with severe trauma, those with prophylactic IVC filter placement did not have a reduced hazard of PE or mortality, but an increased hazard of DVT was observed.

[Urography findings after total cystectomy and urinary diversion]. / Urografifunn etter total cystektomi og urinavledning.

BACKGROUND: Urinary tract obstruction may damage the kidneys, but the interpretation of intravenous urograms is difficult after a total cystectomy for bladder cancer. There is a need for practical guidelines for image reading. MATERIAL AND METHODS: Urograms were routinely taken to control 20 patients (18 men) who had been operated for bladder cancer with total cystectomy and urinary diversion between 1999 and 2004. All patients were examined one or several times at irregular time intervals after surgery. 18 patients were examined within six months after surgery, of whom six were also examined later. Two patients were only examined after six months. Two radiologists reviewed the postoperative urograms by first filling in a standardised form independently of each other and thereafter by filling in the form together according to consensus. The extent of dilatation of the collecting system (calyces, kidney pelvis and ureter) was graded as none, mild, moderate or severe for each side separately. RESULTS: At the first follow-up within six months, six of 18 patients had developed moderate or severe and 10 mild dilatation of the collecting system. The left side was more often dilated (n=7) than the right one (n=1). Both sides were dilated for eight patients; to a moderate/severe degree for two and to a mild degree for six. Of the six patients who were also examined more than 6 months after surgery; one had moderate/severe persistent dilatation and showed signs of regression, three had mild dilatation (two of whom had remission) and two had no dilatation after six months. The patient with a persistently dilated collecting system lost one kidney on the left side despite insertion of a draining ureteral stent. There was a good interobserver agreement concerning the grade of dilatation. INTERPRETATION: Mild dilatation of the collecting system is common after cystectomy and urinary diversion, especially on the left side, and will normalize within a few months in most patients. Persistent dilatation may signify a pathological condition, especially in combination with other radiological findings, such as delayed contrast excretion and obstructed passage in late images.