Dual-energy CT for differentiation of hypodense liver lesions in pancreatic adenocarcinoma

OBJECTIVE

To assess the accuracy of CT spectral HU curve assessment of hypodense liver lesions.

METHODS

In this retrospective HIPAA-compliant study (January 2016 through May 2023), patients with biopsy-proven pancreatic adenocarcinoma and a biopsied indeterminate liver lesion underwent a DECT abdominal CT scan. Spectral HU curves were provided for each hypodense liver lesion, and slopes were calculated. Lesion Hounsfield units, iodine concentration and virtual enhancement were recorded. The Wilcoxon rank sum test was used to compare malignant and benign lesions. Optimal cutoff points were estimated using ROC curves and Youden's Index.

RESULTS

Thirty-six patients (19 men, 17 women) with a mean age of 63 years ± 9 (standard deviation), a mean height of 170.9 cm ± 9.5, a mean weight of 69.8 kg ± 14.5, and a body mass index of 23.9 kg/m2 ± 3.5. Reference standard assessment identified 92 liver lesions (50 metastases, 24 cysts, 13 abscesses, 3 regions of inflammation, 2 hemangiomas) with a mean size of 1.1 cm ± 0.5. The mean interval between the CT and liver lesion biopsy was 24 days. A diagnosis of benign versus malignant was determined based on optimal cutoffs: spectral curve slope of 1.36, iodine concentration of 6.47 (100 µg/cm3), and enhancement of 10.25. The receiver operating curves (ROC) for diagnosis using spectral curve slope, iodine concentration, and virtual enhancement resulted in an area under the curve (AUC) of 0.948, 0.946, and 0.937, respectively.

CONCLUSION

Spectral HU curves and iodine concentration of well-defined hypodense liver lesions are highly accurate in the diagnosis of benign versus malignant lesions.

KEY POINTS

Question Limited evidence exists for spectral imaging diagnosis of liver lesions-can DECT accurately differentiate between benign and metastatic hypodense liver lesions? Findings Ninety-two hypodense liver lesions evaluated using HU keV curve slope, iodine concentration, and virtual enhancement resulted in accurate benign versus metastatic differentiation. Clinical relevance Hypodense liver lesions are a challenging issue at staging, often requiring further imaging, follow-up, and/or biopsy. The additional information from multi-energy CT can be useful to differentiate between benign and malignant lesions, thereby reducing the need for costly additional evaluation.

Spectral CT findings of bladder urothelial carcinoma with gastric metastasis: a case report

BACKGROUND

Bladder cancer is one of the most common cancers worldwide, and urothelial carcinoma is the most common form of bladder cancer. Gastric metastasis of urothelial carcinoma of the bladder is a rare condition. Cystoscopy plays an important role in the diagnosis of bladder cancer; however, it is an invasive procedure that may affect the patient's prognosis and does not allow for the observation of cancer infiltration and metastasis. Therefore, non-invasive imaging is increasingly becoming the most appropriate method for the diagnosis and follow-up of urothelial carcinoma.

CASE PRESENTATION

A 51-year-old female patient presented with pain in the lower abdomen and lower back for more than 2 months. This was a case of bladder urothelial carcinoma with gastric metastases, confirmed by pathology using dual-layer detector computed tomography (CT) spectral multiparametric imaging. The stage of the cancer was cT3N+M1b IVB, and the dimensions were 11.6 mm×42.2 mm×44.4 mm. The energy spectrum multiparameter image shows good consistency in the quantitative measurement of multiple nodules on the gastric wall and bladder wall masses (single energy 40 keV-CT value, iodine concentration, effective atomic number), and the spectral curve runs basically consistent. After 5 months of chemotherapy, the slope values of the spectral curve were 3.74 and 3.09 in the initial and follow-up spectral CT scans, respectively, reflecting the improvement of bladder wall lesions after treatment.

CONCLUSIONS

The present case is a very rare case of bladder urothelial carcinoma with gastric metastasis. We applied multi-parameter quantitative indicators of spectral CT to more accurately show the homology characteristics of gastric metastasis and bladder cancer, and also reflected the different sources of cystic lesions in the left adnexal region from bladder cancer and gastric metastasis. Spectral CT has a promising application prospect in detecting the homology of different lesions and diagnosing urothelial gastric metastasis carcinoma.

Assessing muscle invasion in bladder cancer via virtual biopsy: a study on quantitative parameters and classical radiomics features from dual-energy CT imaging

OBJECTIVE

To evaluate the prediction value of Dual-energy CT (DECT)-based quantitative parameters and radiomics model in preoperatively predicting muscle invasion in bladder cancer (BCa).

MATERIALS AND METHODS

A retrospective study was performed on 126 patients with BCa who underwent DECT urography (DECTU) in our hospital. Patients were randomly divided into training and test cohorts with a ratio of 7:3. Quantitative parameters derived from DECTU were identified through univariate and multivariate logistic regression analysis to construct a DECT model. Radiomics features were extracted from the 40, 70, 100 keV and iodine-based material-decomposition (IMD) images in the venous phase to construct radiomics models from individual and combined images using a support vector machine classifier, and the optimal performing model was chosen as the final radiomics model. Subsequently, a fusion model combining the DECT parameters and the radiomics model was established. The diagnostic performances of all three models were evaluated through receiver operating characteristic (ROC) curves and the clinical usefulness was estimated using decision curve analysis (DCA).

RESULTS

The normalized iodine concentration (NIC) in DECT was an independent factor in diagnosing muscle invasion of BCa. The optimal multi-image radiomics model had predictive performance with an area-under-the-curve (AUC) of 0.867 in the test cohort, better than the AUC = 0.704 with NIC. The fusion model showed an increased level of performance, although the difference in AUC (0.893) was not statistically significant. Additionally, it demonstrated superior performance in DCA. For lesions smaller than 3 cm, the fusion model showed a high predictive capability, achieving an AUC value of 0.911. There was a slight improvement in model performance, although the difference was not statistically significant. This improvement was observed when comparing the AUC values of the DECT and radiomics models, which were 0.726 and 0.884, respectively.

CONCLUSION

The proposed fusion model combing NIC and the optimal multi-image radiomics model in DECT showed good diagnostic capability in predicting muscle invasiveness of BCa.

Dual-Energy Computed Tomography in Urological Diseases: A Narrative Review

Dual-Energy computed tomography (DECT) with its various advanced techniques, including Virtual Non-Contrast (VNC), effective atomic number (Z-eff) calculation, Z-maps, Iodine Density Index (IDI), and so on, holds great promise in the diagnosis and management of urogenital tumours. In this narrative review, we analyze the current status of knowledge of this technology to provide better lesion characterization, improve the staging accuracy, and give more precise treatment response assessments in relation to urological tumours.

Expanding Role of Dual-Energy CT for Genitourinary Tract Assessment in the Emergency Department, From the AJR Special Series on Emergency Radiology

Among explored applications of dual-energy CT (DECT) in the abdomen and pelvis, the genitourinary (GU) tract represents an area where accumulated evidence has established the role of DECT to provide useful information that may change management. This review discusses established applications of DECT for GU tract assessment in the emergency department (ED) setting, including characterization of renal stones, evaluation of traumatic injuries and hemorrhage, and characterization of incidental renal and adrenal findings. Use of DECT for such applications can reduce the need for additional multiphase CT or MRI examinations and reduce follow-up imaging recommendations. Emerging applications are also highlighted, including use of low-energy virtual monoenergetic images (VMIs) to improve image quality and potentially reduce contrast media doses and use of high-energy VMIs to mitigate renal mass pseudoenhancement. Finally, implementation of DECT into busy ED radiology practices is presented, weighing the trade-off of additional image acquisition, processing time, and interpretation time against potential additional useful clinical information. Automatic generation of DECT-derived images with direct PACS transfer can facilitate radiologists' adoption of DECT in busy ED environments and minimize impact on interpretation times. Using the described approaches, radiologists can apply DECT technology to improve the quality and efficiency of care in the ED.

Dual-Energy Computed Tomography Applications in the Genitourinary Tract

By virtue of material differentiation capabilities afforded through dedicated postprocessing algorithms, dual-energy CT (DECT) has been shown to provide benefit in the evaluation of various diseases. In this article, we review the diagnostic use of DECT in the assessment of genitourinary diseases, with emphasis on its role in renal stone characterization, incidental renal and adrenal lesion characterization, retroperitoneal trauma, reduction of radiation, and contrast dose and cost-effectiveness potential. We also discuss future perspectives of the DECT scanning mode, including the use of novel contrast injection strategies and photon-counting detector computed tomography.

Dual-Energy CT applications in urinary tract cancers: an update

Urothelial tumours are the fourth most common cancer in the world and account for the majority of tumours involving the bladder. The symptom that often leads to diagnosis is the presence of haematuria. Diagnosis is made by cystoscopy, which is currently the gold standard in bladder cancer. Computed tomography (CT) performed with pre- and post-contrastographic phases is essential in order to assess the loco-regional and distant extension of disease. The diagnosis and staging of upper tract urothelial cancer (UTUC) are best done with computed tomography urography and flexible ureteroscopy (URS). In the acquisition protocol of this type of tumour, a urographic phase is mandatory, which allows for an accurate diagnostic assessment of the renal pelvis, ureter and bladder, especially in papillary forms. The use of multiple acquisition phases, especially in this type of patient who will have to perform follow-up CTs, leads to the problem of overexposure to ionising radiation, as well as the frequent administration of iodinated contrast medium. For this reason, in recent year, the focus has been put on advanced technologies such as dual-energy CT (DECT), that is a method that can offer some advantages for both radiologist and patient, in the diagnosis of cancer and, in particular, urinary tract disease.

CT urography: how to optimize the technique

PURPOSE

Computed tomography urography (CTU) has emerged as the modality of choice for imaging the urinary tract within the past few decades. It is a powerful tool that enables detailed anatomic evaluation of the urinary tract in order to identify primary urothelial malignancies, benign urinary tract conditions, and associated abdominopelvic pathologies. As such, there have been extensive efforts to optimize CTU protocol.

METHODS

This article reviews the published literature on CTU protocol optimization, including contrast bolus timing, dose reduction, reconstruction algorithms, and ancillary practices.

CONCLUSION

There have been many advances in CTU techniques, which allow for imaging diagnosis of a wide spectrum of diseases while minimizing radiation dose and maximizing urinary tract distension and opacification.

Low-keV virtual monoenergetic imaging reconstructions of excretory phase spectral dual-energy CT in patients with urothelial carcinoma: A feasibility study

OBJECTIVES

To compare objective and subjective image quality between low keV virtual monoenergetic images (VMI) of the excretory phase and conventional venous phase images derived from spectral dual-energy CT (DECT) in the assessment of urothelial carcinoma.

METHODS

26 consecutive patients with histologically confirmed urothelial carcinoma who received clinically indicated venous- and excretory phase abdominal CT scans were included retrospectively. Attenuation, image noise as well as signal- and contrast-to-noise-ratio (SNR, CNR) in venous and excretory phase CT and excretory phase VMI from 40 to 70 keV were obtained from ROI-based measurements in the following regions: urothelial carcinoma, liver, pancreas, renal cortex, subcutaneous fat, renal vein/artery, portal vein, urinary bladder wall, lymph nodes, prostate/uterus. Subjective vessel contrast and delineation of primary tumor manifestations and distant metastases were rated on 5-point Likert scales.

RESULTS

In comparison to venous phase CT, attenuation and SNR in excretory phase VMI40keV were higher (p < 0.001), except for liver parenchyma, where they were comparable (p = 0.07 and p = 0.17, respectively). Regarding image noise, no significant difference was found between venous phase CT and excretory phase VMI40keV (p-range: 0.08-1.00), except for liver, portal vein and renal artery, where it was lower in VMI40keV (p < 0.05). CNR of urothelial carcinoma to circumjacent bladder wall was significantly higher in excretory phase VMI40keV compared to venous phase CT. Subjective vessel contrast and delineation of primary tumor and distant metastases received equivalent or higher Likert scores in excretory phase VMI40keV than in venous phase CT.

CONCLUSION

This feasibility study indicates that in the assessment of urothelial carcinoma, virtual monoenergetic excretory phase images at 40 keV acquired with spectral DECT could be feasible to maintain subjective and objective image quality as provided by conventional venous phase images. Still, equivalence with regards to metastatic lesion detection requires further investigation before employing this technique in a potential signal-scan, single-bolus approach.

Use of Dual-Energy Computed Tomography for Evaluation of Genitourinary Diseases

Since its clinical inception a decade ago, dual-energy computed tomography has expanded the array of computed tomography imaging tools available to the practicing abdominal radiologist. Of note, diagnostic solutions for imaging-based evaluation of genitourinary diseases, foremost kidney calculi and renal tumors characterization, represent the apogee applications of dual-energy computed tomography in abdominal imaging. This article reviews clinical applications of dual-energy computed tomography for the assessment of genitourinary diseases.

Dual-Energy Computed Tomography in Genitourinary Imaging

Reignited by innovations in scanner engineering and software design, dual-energy computed tomography (CT) has come back into the clinical radiology arena in the last decade. Possibilities for noninvasive in vivo characterization of genitourinary disease, especially for renal stones and renal masses, have become the pinnacle offerings of dual-energy CT for body imaging in clinical practice. This article renders a state-of-the-art review on clinical applications of dual-energy CT in genitourinary imaging.

White Paper of the Society of Computed Body Tomography and Magnetic Resonance on Dual-Energy CT, Part 4: Abdominal and Pelvic Applications

This is the fourth of a series of 4 white papers that represent expert consensus documents developed by the Society of Computed Body Tomography and Magnetic Resonance through its task force on dual-energy computed tomography. This article, part 4, discusses DECT for abdominal and pelvic applications and, at the end of each, will offer our consensus opinions on the current clinical utility of the application and opportunities for further research.