Spatial and temporal variations of coastal microplastic pollution in Hong Kong

Further to our 2015-16 investigation, this study revealed the repeated presence of microplastics (MPs) in the coastal environment (Deep Bay, Tolo Harbour, Tsing Yi and Victoria Harbour) of Hong Kong from July 2016 to March 2017. The highest level of MPs in coastal surface water (17,182 particles/100 m³) was detected in Tsing Yi. Microplastic abundance in sediments of different sites (59 to 225 plastic particles/kg), however, did not vary significantly. MPs in the size of ≤1 mm were predominated in surface waters (53.3% to 98.6%) and sediments (79.1% to 96.8%). MPs in the shape of pellets and fragments were prevalent in surface waters and sediments respectively. Seasonal pattern of microplastic pollution was consistently observed in Victoria Harbour and Tsing Yi, where the number of MPs was always higher in dry season than in wet season for two consecutive years.

Unenhanced multidetector computed tomography findings in acute central pulmonary embolism

Background

Computed tomography pulmonary angiography (CTPA) is the gold standard for the diagnosis of pulmonary embolism (PE). However, contrast is contraindicated in some patients. The purpose of this study was to determine the diagnostic accuracy of unenhanced multidetector CT (MDCT) for diagnosis of central PE using CTPA as the gold standard.

Methods

The records of patients with suspected PE seen between 2010 and 2013 were retrospectively reviewed. Inclusion criteria were an acute, central PE confirmed by CTPA and non-enhanced MDCT before contrast injection. Patients with a PE ruled out by CTPA served as a control group. MDCT findings studied were high-attenuation emboli in pulmonary artery (PA), main PA dilatation > 33.2 mm, and peripheral wedge-shaped consolidation. Receiver operating characteristic (ROC) analysis was used to determine the sensitivity and specificity of unenhanced MDCT to detect PE. Wells score of all patients were calculated using data extracted from medical records prior to imaging analysis.

Results

Thirty-two patients with a PE confirmed by CTPA and 32 with a PE ruled out by CTPA were included. Among the three main MDCT findings, high-attenuation emboli in the PA showed best diagnostic performance (Sensitivity 72.9%; Specificity 100%), followed by main PA dilatation > 33.2 mm (sensitivity 46.9%; specificity 90.6%), and peripheral wedge-shaped consolidation (sensitivity 43.8%; specificity 78.1%). Given any one or more positive findings on unenhanced MDCT, the sensitivity was 96.9% and specificity was 71.9% for a diagnosis of PE in patients. The area under the curve (AUC) of a composite measure of unenhanced MDCT findings (0.909) was significantly higher than that of the Wells score (0.688), indicating unenhanced MDCT was reliable for detecting PE than Wells score.

Conclusions

Unenhanced MDCT is an alternative for the diagnosis of acute central PE when CTPA is not available.

Gadoxetic acid-enhanced magnetic resonance imaging can predict the pathologic stage of solitary hepatocellular carcinoma

BACKGROUND

Although important for determining long-term outcome, pathologic stage of hepatocellular carcinoma (HCC) is difficult to predict before surgery. Current state-of-the-art magnetic resonance imaging (MRI) using gadoxetic acid provides many imaging features that could potentially be used to classify single HCC as pT1 or pT2.

AIM

To determine which gadoxetic acid-enhanced MRI (EOB-MRI) findings predict pathologic stage T2 in patients with solitary HCC (cT1).

METHODS

Pre-operative EOB-MRI findings were reviewed in a retrospective cohort of patients with solitary HCC. The following imaging features were examined: Hyperintensity in unenhanced T2-weighted images, hypointensity in unenhanced T1-weighted images, arterial enhancement, corona enhancement, washout appearance, capsular appearance, hypointensity in the tumor tissue during the hepatobiliary (HB) phase, peritumoral hypointensity in the HB phase, hypointense rim in the HB phase, intratumoral fat, hyperintensity on diffusion-weighted imaging, hypointensity on apparent diffusion coefficient map, mosaic appearance, nodule-in-nodule appearance, and the margin (smooth or irregular). Surgical pathology was used as the reference method for tumor staging. Univariate and multivariate analyses were performed to identify predictors of microvascular invasion or satellite nodules.

RESULTS

There were 39 (34.2%; 39 of 114) and 75 (65.8%; 75 of 114) pathological stage T2 and T1 HCCs, respectively. Large tumor size (≥ 2.3 cm) and two MRI findings, i.e., corona enhancement [odds ratio = 2.67; 95% confidence interval: 1.101-6.480] and peritumoral hypointensity in HB phase images (odds ratio = 2.203; 95% confidence interval: 0.961-5.049) were associated with high risk of pT2 HCC. The positive likelihood ratio was 6.25 (95% confidence interval: 1.788-21.845), and sensitivity of EOB-MRI for detecting pT2 HCC was 86.2% when two or three of these MRI features were present. Small tumor size and hypointense rim in the HB phase were regarded as benign features. Small HCCs with hypointense rim but not associated with aggressive features were mostly pT1 lesions (specificity, 100%).

CONCLUSION

Imaging features on EOB-MRI could potentially be used to predict the pathologic stage of solitary HCC (cT1) as pT1 or pT2.

Microplastic pollution in the marine waters and sediments of Hong Kong

The presence of plastic waste with a diameter of less than 5mm ("microplastics") in marine environments has prompted increasing concern in recent years, both locally and globally. We conducted seasonal surveys of microplastic pollution in the surface waters and sediments from Deep Bay, Tolo Harbor, Tsing Yi, and Victoria Harbor in Hong Kong between June 2015 and March 2016. The average concentrations of microplastics in local coastal waters and sediments respectively ranged from 51 to 27,909particles per 100m³ and 49 to 279particles per kilogram. Microplastics of different shapes (mainly fragments, lines, fibers, and pellets) were identified as polypropylene, low-density polyethylene, high-density polyethylene, a blend of polypropylene and ethylene propylene, and styrene acrylonitrile by means of Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy. This is the first comprehensive study to assess the spatial and temporal variations of microplastic pollution in Hong Kong coastal regions.

A comparison of pyelography and various reconstructions of multidetector helical computed tomography urography images for diagnosing urinary obstruction

Radiologists and urologists require practical and helpful image reconstructions for diagnosing urinary obstruction. We performed different types of imaging and reconstruction, then used a self-designed urinary obstruction-specific questionnaire to evaluate the diagnostic outcome of them. Our results suggested that two-dimensional (2D) axial computed tomography (CT) is clinically superior to retrograde pyelography or antegrade pyelography, and to other modes of image reconstruction that are often used for diagnosing urinary obstruction.

An unusual appearance of renal epithelioid angiomyolipoma

Epithelioid angiomyolipoma is a recently described rare variant of renal angiomyolipoma. It can occur in patients with or without tuberous sclerosis. We report the imaging findings of a case of epithelioid angiomyolipoma that showed the presence of fatty tissue undifferentiated from the typical angiomyolipoma at the beginning. After partial nephrectomy, tumour recurrence occurred two years later, presenting as completely solid tumours with no adipose tissue, and with invasion into the psoas muscle and left adrenal gland. Differentiation of this tumour from renal cell carcinoma is difficult. Both the radiologist and surgeon should be aware of the existence of this tumour and its potentially malignant behaviour.

CT-guided transthoracic cutting needle biopsy of intrathoracic lesions: comparison between coaxial and single needle technique

PURPOSE

To evaluate the complication rates and diagnostic accuracy of two different CT-guided transthoracic cutting needle biopsy techniques: coaxial method and single needle method.

METHODS

This study involved 198 consecutive subjects with 198 intrathoracic lesions. The first 98 consecutive subjects received a single needle cutting technique and the next 100 consecutive subjects received a coaxial technique. Both groups were compared in relation the diagnostic accuracy and complication rates.

RESULTS

No significant difference was found between the two groups concerning patient characteristics, lesions and procedure variables. There was a borderline statistical difference in the incidence of pneumothorax at within 24-h post biopsy between patients in the single needle group (5%) and the coaxial group (13%) (P=0.053). Little difference was found in the pneumothorax rate at immediately post biopsy between the two groups, which was 28% in the single needle group and 31% in the coaxial group. There was no significant difference in the hemoptysis rate between the two groups, which was 9.2% in the single needle group and 11% in the coaxial group. Both techniques yielded an overall diagnostic accuracy of 98% for malignant lesions with similar sensitivity (single needle: 96.9% vs. coaxial: 96.4%) and specificity (single needle: 100% vs. coaxial: 100%).

CONCLUSION

There is little difference in the pneumothorax rates and bleeding complications between patients who either received a single needle or a coaxial transthoracic cutting biopsy. Both techniques produce an overall diagnostic accuracy of 98% for malignant lesions.

Computed tomography appearance of ovarian fibrothecomas with and without torsion

BACKGROUND

Fibrothecomas are the most common solid ovarian tumors and may undergo torsion. Early diagnosis of these tumors is important in order to allow prompt surgical treatment.

PURPOSE

To describe the features of ovarian fibrothecoma on computed tomography (CT) and to determine the possibility of detecting tumor torsion in this kind of tumor.

MATERIAL AND METHODS

The CT images of 11 patients with ovarian fibrothecomas in the past 8 years at our hospital were retrospectively reviewed. The CT attenuation values of each tumor were measured in both non-enhanced and enhanced scans. The size and degree of enhancement were evaluated and correlated with tumor torsion. All cases were pathologically proven.

RESULTS

Three kinds of tumor pattern were found: 1) homogeneous tumor with significant enhancement containing scattered, low-attenuated regions after contrast injection; 2) heterogeneous tumor with mild enhancement after contrast injection; and 3) low-attenuated soft-tissue mass with no obvious enhancement after contrast injection.

CONCLUSION

Fibrothecomas usually appear as a homogeneous solid tumor with varying degrees of enhancement. Calcification may be present and, as these tumors enlarge, myxoid or cystic degeneration may occur, resulting in a heterogeneous pattern. The larger the tumor, the greater is the chance of torsion. Lack of tumor enhancement is the most reliable sign for detection of ovarian torsion and should facilitate prompt surgical intervention to remove damaged tissue.

Sonographic appearance of angiolymphoid hyperplasia with eosinophilia in the upper arm

Angiolymphoid hyperplasia with eosinophilia is an uncommon benign condition characterized by cutaneous nodules involving primarily the head and neck regions of young adults. We report thecase of a 49-year-old woman with such a lesion in the arm. Sonographically, the lesion exhibited a hypoechoic rim and an echogenic central portion. On color Doppler imaging, the central portion was markedly vascular.

Epidermoid cyst of the testis

Epidermoid cysts, though having a variable sonographic appearance, may present with an onion peel configuration, that is, concentric rings of alternating hyperechogenicities and hypoechogenicities. The absence of vascular flow on colour Doppler sonography is also consistent with the avascular nature of these lesions. By combining these two sonographic features and the absence of biochemical tumour marker, preoperative diagnosis of epidermoid cyst is possible and may prompt a testis sparing surgery rather than orchidectomy.

Clinical significance of poor CT enhancement of the thickened small-bowel wall in patients with acute abdominal pain

OBJECTIVE

Our purpose was to compare clinical outcomes in patients with acute abdominal pain and inner-layer enhancement of a thickened small-bowel wall, as shown on CT, with outcomes in similar patients without such enhancement.

MATERIALS AND METHODS

We retrospectively studied outcomes in 126 patients with acute abdominal pain and small-bowel wall thickening on CT: 84 with inner-layer enhancement and 42 without this enhancement. We compared the surgical, small-bowel resection, small-bowel necrosis, and mortality rates between the two groups using the chi-square test.

RESULTS

Among the 42 patients without inner-layer enhancement, 32 (76%) underwent an operation, 27 (64%) received segmental small-bowel resection, 26 (62%) had small-bowel necrosis, and seven (17%) died. All of these proportions were significantly higher (p < 0.01) than the corresponding rates-34 (40%), nine (11%), five (6%), and two (2%), respectively-in the 84 patients with inner-layer enhancement. All 31 patients with necrotic small bowel had pathologic evidence of ischemic necrosis involving the mucosa.

CONCLUSION

Among patients with acute abdominal pain, those whose CT scans did not show inner-layer enhancement of a thickened small-bowel wall were more prone to undergo surgery and small-bowel resection and were more likely to have small-bowel necrosis than those with such enhancement. Poor inner-layer enhancement on CT might be consistent with sloughed or necrotic mucosa, as observed on pathology.

Computed tomography features of spontaneously perforated pyometra: a case report

Spontaneous perforation of pyometra is an extremely rare emergent gynecologic disease. We report a 73-year-old woman with a spontaneously perforated pyometra presenting with acute abdomen in the emergency department. A dedicated computed tomography examination of the abdominal and pelvic regions revealed the diagnosis. The patient recovered well after surgical intervention and antibiotic treatment.

Malignant mesothelioma of the tunica vaginalis testis: unusual sonographic appearance

Malignant mesothelioma of the tunica vaginalis testis is a rare and aggressive neoplasm. It is similar to malignant mesothelioma of the peritoneum, usually associated with asbestos exposure. We present an unusual case in which the tumor was a mix of a hypoechoic solid nodule and a cystic component with low-level internal echoes.

Malignant mesothelioma of the tunica vaginalis testis

Malignant mesothelioma of the tunica vaginalis is rare, and is usually not diagnosed until surgery is undertaken. Reports on the ultrasound features of this tumour are limited. We present an unusual case with ultrasound features mimicking an adenomatoid tumour.

Leiomyoma arising from the tunica albuginea of the testis: sonographic findings

Leiomyomas are benign neoplasms that may arise from any structure or organ containing smooth muscle. The majority of genitourinary leimyomas are found in the renal capsule, but this tumor has also been reported in the epididymis, spermatic cord, and tunica albuginea. Sonography is the imaging modality of choice for evaluating intrascrotal pathology, but the sonographic appearance of leiomyomas arising from the tunica albuginea have rarely been reported. We report a case of such a leiomyoma that was diagnosed sonographically.

CT of small bowel ischemia

We evaluated the computed tomographic (CT) features of small bowel (SB) ischemia and necrosis and correlated the findings with clinical outcome or patient prognosis. Sixty-eight surgically or angiographically proved cases of SB ischemia were retrospectively reviewed. The CT features of intestinal ischemia were divided into three groups: (A) thinned bowel wall with poor enhancement, intramural gas, or portal venous gas; (B) thickened SB wall without superior mesenteric vein thrombosis; and (C) thickened SB wall with superior mesenteric vein thrombosis or intussusception. The evaluated factors included bowel wall or mucosal enhancement pattern, SB dilatation, mesenteric edema, and CT evidence of narrowing or occlusion of the superior mesenteric artery or vein. The bowel necrosis rates and mortalities were compared with chi-square test. Oral contrast material was not administered. Intramural gas and SB dilatation were associated with a higher bowel necrosis rate (eight of eight, 100%, and 17 of 21, 81%, respectively) in group A. Poor mucosal enhancement of the thickened bowel wall indicated a higher bowel necrosis rate in groups B (six of seven, 86%) and C (12 of 12, 100%) than did normal mucosal enhancement. Only intramural gas was accompanied with a higher mortality (six of eight, 75%). Intramural gas of a thinned bowel wall and poor mucosal enhancement of a thickened small bowel wall are useful signs of bowel necrosis. Intramural gas would indicate poor patient prognosis.

Ultrasound diagnosis of paratesticular rhabdomyosarcoma

Rhabdomyosarcoma is the most common tumour of the lower genitourinary tract in children in the first two decades. Paratesticular rhabdomyosarcoma is associated with a significantly better outcome than lesions elsewhere in the genitourinary tract. Although ultrasound is considered the imaging modality of choice for evaluating intrascrotal pathology, the ultrasound appearance of paratesticular rhabdomyosarcoma has rarely been reported and may be confused with other disease entities such as epididymitis, adenomatoid tumour and leiomyoma. We present the ultrasound features of a paratesticular rhabdomyosarcoma, discussing the clinical features and differential diagnosis.

Case report: diabetic mastopathy

Diabetic mastopathy is a source of confusion with breast carcinoma. The association between mastopathy and Type I diabetes of long duration has been reported, but this clinical condition is poorly recognized since breast examination is not routinely performed in young diabetic patients. Radiologists' awareness of the constellation of findings in diabetic mastopathy may spare patients from undergoing unwarranted surgical biopsies.

Prenatal diagnosis of congenital mesoblastic nephroma in mid-second trimester by sonography and magnetic resonance imaging

Although congenital mesoblastic nephroma (CMN) is a rare benign congenital renal tumor, it is the most common solid renal tumor in the newborn period. The most common presentation of congenital mesoblastic nephroma is polyhydramnios, and only one case with prenatal fetal hydrops has been previously reported. Prenatal diagnosis of CMN has previously been made on the basis of the findings of sonography in the third trimester, and magnetic resonance imaging (MRI)-based diagnosis has been reported recently. Here we report a case of prenatally diagnosed classical type CMN diagnosed at 22 + 3 weeks of gestation based on the findings of sonography and magnetic resonance imaging. The characteristic imaging findings in this case were fetal hydrops and polyhydramnios. To our knowledge, this is the youngest reported gestational age for prenatal diagnosis of CMN and it is the second case of CMN associated with fetal hydrops detected prenatally.

Differentiation of obstructive from non-obstructive small bowel dilatation on CT

PURPOSE

to find a useful decision procedure for the differentiation of obstructive from non-obstructive small bowel (SB) dilatation on the computed tomography (CT).

MATERIALS AND METHODS

four criteria were divided into different degrees and evaluated. These include: (A): continuity (non-continuous, continuous); (B): transition zone (absent, gradual, abrupt); (C): prestenotic SB fluid (minimal, about one-fourth, one-half, and three-fourths, nearly complete); and (D): colonic contents (minimal, moderate, considerable). One hundred fifty-three examinations, 86 obstructive and 67 non-obstructive, were analyzed using chi(2)-square tests to determine the relationship of each criterion to the presence of small bowel obstruction (SBO), whether the proportions of various degrees of these criteria differed significantly among the obstructive and non-obstructive subgroups, and to classify the criteria with a tree-based model (calculated by the computer) for the development of a useful decision procedure.

RESULTS

in each of the four criteria, the trend of probability of obstruction was statistically significant (P=0.0000). The proportions of most, except two, of the various degrees of different criteria in the obstructive and non-obstructive subgroups differed significantly (P<0.01). The obstruction tends to have a continuou dilatation, an abrupt transition, more prestenotic SB fluids, and less colonic contents. The results of classification by a tree-based model were 76 true-positive, ten false-negative, six false-positive, and 61 true-negative. The sensitivity was 88%; specificity was 91%; positive predictive value was 93%; negative predictive value was 86%; and the overall accuracy was 90%.

CONCLUSION

by analyzing the above four criteria together, a useful tree-based model can be developed and utilized as a supplemental decision procedure for the differentiation of obstructive from non-obstructive SB dilatation. The accuracy can be further promoted if the factor of a recognized pathologic condition is taken into consideration.

CT of agenesis and atrophy of the right hepatic lobe

BACKGROUND

To identify and differentiate agenesis and severe atrophy of the right hepatic lobe on computed tomography (CT).

METHODS

The CT examinations of three cases of agenesis and 11 cases of severe atrophy of the right hepatic lobe were reviewed. We evaluated visibility of the three hepatic veins, the two main portal veins (including their branches if necessary), the dilated intrahepatic ducts, enlargement of the medial and lateral segments of the left lobe and caudate lobe of the liver, presence of a retrohepatic gallbladder, hyperattenuation of the atrophic liver parenchyma, posterolateral interposition of the hepatic flexure of the colon, and upward migration of the right kidney.

RESULTS

In the three cases of agenesis, no structure can be recognized as the right hepatic vein, right portal vein, or dilated right intrahepatic ducts. In the 11 cases of severe lobar atrophy, the right portal vein (or its branches) was recognized in eight cases, the right hepatic vein in four cases, and the dilated right intrahepatic ducts in 11 cases. The degree of enlargement of the lateral segment does not necessarily change inversely with the size of the medial segment and the caudate lobe. The retrohepatic gallbladder is present in eight cases (two in agenesis and six in atrophy). The phenomenon of hyperattenuation of the atrophic liver parenchyma was noted in six cases.

CONCLUSION

Even though a retrohepatic gallbladder and a severely distorted hepatic morphology due to compensatory hypertrophy of the left and caudate lobes may raise a suspicion of agenesis of the right lobe of the liver, absence of visualization of all of the right hepatic vein, right portal vein and its branches, and dilated right intrahepatic ducts is a prerequisite of the diagnosis of agenesis of the right hepatic lobe on CT. In severe lobar atrophy, at least one of these structures is recognizable.

CT of large small-bowel diverticulum

The previous reports concerning the computed tomographic (CT) appearances of small bowel diverticulum are usually limited to those of diverticulitis. We present the CT findings of uncomplicated, large small bowel diverticulum in five patients. An interesting coexistence of large small bowel diverticulum and small bowel volvulus will be mentioned. Four patients had recurrent abdominal pain in the past 2 years.

CT of the mesenteric vascular anatomy

BACKGROUND

To evaluate the appearance of the arrangement of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) on computed tomography (CT) in normal patients and in patients with abdominal masses.

METHODS

One hundred seventy-seven consecutive abdominal CT examinations of 143 adults and two children were reviewed. The relationship of the SMV to the SMA was recorded at four locations: the beginning of the mesenteric vessels and levels 3 cm, 6 cm, and 9 cm caudad to the beginning. The relationship of the SMV to the SMA was divided into four quadrants in relation to the SMA: I, ventral right or directly ventral; II, dorsal right or directly right; III, dorsal left or directly dorsal; and IV, ventral left or directly left.

RESULTS

In the beginning of the SMV-SMA complex and levels 3 cm, 6 cm, and 9 cm caudal to the beginning, the SMV was located in quadrant I in 146, 84, 69, and 43 examinations, in quadrant II in 31, 93, 71, and 27 examinations, in quadrant III in zero, zero, five, and three examinations, and in quadrant IV in zero, zero, nine, and 15 examinations, respectively. The cases with SMV inversion had neither malrotation nor adjacent tumor compression. All the cases with an adjacent tumor-induced compression of the SMV-SMA complex had a normal SMV-SMA relationship.

CONCLUSION

In the first 3 cm, the SMV is always to the right of the SMA. Caudal to the level of 6 cm, the SMV may be located to the left of the SMA without evidence of malrotation. A midgut nonrotation is more likely to be present when a proximal SMV inversion is coexistent with a rightward direction of the proximal jejunal vessels. A hypothetical depiction of the step-by-step change of the SMV-SMA relationship during embryologic development may explain the arrangement patterns of the mesenteric vessels in normal rotation and midgut nonrotation.

CT of the duodenojejunal junction

To determine the location of the duodenojejunal junction (DJJ) at computed tomography (CT), we retrospectively reviewed 309 consecutive CT examinations. These included 162 men and 127 women (mean age = 57 years old, range = 11-85 years old). Some people received more than one examination. The clinical indications included various kinds of neoplasms, inflammations, congenital lesions, trauma, and other conditions. The DJJ was defined as the first sectioned ascending duodenum whose major part lies to the right side of the crossing part of the inferior mesenteric vein over the immediate beginning of the jejunum. Forty-nine examinations were excluded due to distortion of the DJJ by contiguous pathologic processes or nonadministration of intravenous contrast medium. In 36 examinations, the junctions were not identified. In the successfully identified 224 examinations, the DJJ was located to the left in 75 (33.5%), in the left half in 87 (38.8%), and in the right half or to the right of the vertebral body in 4 (1.8%) examinations. The midline of the DJJ was along the left margin and in the midline of the vertebral body in 53 (23.7%) and 5 (2.2%) examinations. In the anteroposterior direction, it was totally in front of the aorta in 189 (84.4%) and within the projected contour of the aorta in 11 (4.9%) examinations. The midline of the DJJ was along the anterior margin of the aorta in 24 (10.7%) examinations. Its cephalocaudal position was at the upper L1 in 36 (16.1%), lower L1 in 70 (31.3%), upper L2 in 75 (33.5%), and lower L2 in 21 (9.4%) examinations even though it ranged from upper T12 to upper L3.(ABSTRACT TRUNCATED AT 250 WORDS)